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Archive-name: bicycles-faq/part3 [Note: The complete FAQ is available via anonymous ftp from draco.acs.uci.edu (128.200.34.12), in pub/rec.bicycles.] --------------------------------------------------------------------------- Studded Tires (Nancy Piltch piltch@ariel.lerc.nasa.gov) [A summary on studded tires compiled by Nancy. A complete copy of the responses she received, including some that give directions for making your own studded tires, is in the archive.] Studded tires do help, especially on packed snow and ice. On fresh snow and on water mixed with snow (i.e. slush) they're not significantly different from unstudded knobbies. On dry pavement they are noisy and heavy, but can be used; watch out for cornering, which is degraded compared to unstudded tires. Several people recommend a Mr. Tuffy or equivalent with them; one respondent says he gets more flats with a liner than without. In the U.S. the IRC Blizzard tires are commercially available. They can also be made. --------------------------------------------------------------------------- Milk Jug Mud Flaps (Chuck Tryon bilbo@bisco.kodak.com) Actually, I have used plastic like this (or in my case, some red plastic from a cheap note book cover -- it's heavier) to extend the bottom (rear) end of the front fender. The Zephals are good, but they don't stop the splash from where the tire hits the road from getting on my feet. What I did was cut a small triangle about 3in (~7cm) wide by 6in (~15cm) long, cut a hole in the top of it and the bottom end of the fender, and use a pop-rivet (with washers to prevent tear out) to attach it. On a road bike, it should be end up being within a few inches of the road. ATB's will need more clearance, so this won't work well off road. | | | | /| o |\ <----- rivet with washer on inside | \___/ | / \ <---- flap fits inside of the fender, and follows the | | curve, which gives it some stiffness. | | | | \_________/ | | | | <----- bottom of tire \_/ =========================================================================== Touring Touring supplies (Scott "gaspo" Gasparian gaspar@inf.ethz.ch) Recently, I asked the group: what do you bring with you on medium trips? (medium being more than one nite, and less than a week). I received some excellent replies, a few great stories, and lots of things that I never would have thought of. (at least not until I needed that spare spoke that is). Ok, for all of you who don't know what to bring with you on that next medium trip... FOOD: Here, just whatever you normally consume. If you plan on staying in a hotel/B&B, then obviously 1 day's worth is enough. Standard things like power-bars and drink mixes should do the trick. Since I'm not going to BFE, I have no idea what to pack for a real "camp-out" type tour. This subject is enough for a discussion in itself, but I just eat what I want. CLOTHING: Almost everybody suggested something different, rangin from hi- tech bodysuits to cutoffs and T-shirts. However, everybody agreed on the indispensibleness (tm) of rain gear. Specifically, light waterproof pants and jacket are not only good for staying dry, but have a very high warmth/weight ratio. A spare change of skivies, and a pair of dry socks were also highly recomended. A pair of jeans or a "smushable outfit" can come in handy, but I usually smell so bad after a day of riding that anybody who is talking to me doesn't care what I wear. If it might be non-warm, a watch-cap or other non-helmet type hat can help. FIRST-AID: Outside of the standard band-aids/antiseptic-goop bit, sunscreen and bug-away topped the lists. Asprin or Ibuprofen and rolaids were mentioned, but I guess thats a personal thing, just like... TOILETRIES: I stick with: soap, toothbrush/paste, deodorant. That covers all I need, but everybody has different needs, and I'm not even gonna touch the "personal hygeine" stuff. A razor is handy too, it can help keep that road-rash dressing from ripping all your remaining hair out. MISC: I'll put the tent/pit stuff into this category. Robyn Stewart gave an excellent testamony to the uses of rope and tarps. A piece of rope stretched between two trees can keep the food above the critter-level, and can also provide a rudimentary tent with the aid of an old shower-curtain. Again, there is a whole area of discussion here on the pits and mattresses, but if it keeps you warm and dry, it works. TOOLS: Basically, this could be split into two different classes, with things like tire-kit being in the "fix it yourself" category, and other stuff like a chain remover tool is in the "how far will I be from civilization" range. This was what I really wanted to know about when I posted my request, so a little more info than the first groups. Most of this depends upon how much work _YOU_ do to your velo. If replacing spokes is trivial to you, then you already know what tools to bring. Also, wrenches and screwdrivers are very velo dependent: handy sizes for a MTB might be useless for a nice racer, and vice-versa. Tools that tune more than repair are also an individual call. I always carry a hex-wrench that fits my brake-shoe adjustment bolt, but never the larger one that actually removes the entire caliper. pump pressure gauge flat kit wrenches (sizes and type for your velo) hex(allen)-wrenches (sizes and type for your velo) chain tool chain links tire levers (plastic) spoke wrench safety wire duct tape zip ties SPARES: Again, these fall into "distance from civilization" categories. For example, that nut that connects your front mudguard to the forks is essential, but could be fixed with the safety wire until you find a velo-shop/store that might have a replacement. Then again, one little nut is easy on space/weight, and it may be hard to get a replacement if your velos measurements are non-standard. If you have a hard-time finding a replacement for that random part at your local store, bring one with you. inner tubes tire-boots brake shoes light bulbs spokes (labeled if different, tied to the frame) nuts and bolts for rack/fenders/etc. tire (if you're _really_ out there) toe-clip strap shoe-laces cable (especially if yours are longer than normal). cable housing (for the shimano special shifter ones) NIFTY IDEAS: Here are some of the better inside tips that I found both humorous and usefull.... mjohnsto@shearson.com (Mike Johnston) A sock (to keep tools inside and for keeping grease off my hands during rear wheel flats) s_kbca@dante.lbl.gov (Steve Kromer) The most important article to take along on a long ride seems to be faith. chris@wg.estec.esa.nl (chris rouch) 15cm of old tyre Robyn Stewart <slais02@unixg.ubc.ca> Enough money to get Greyhound home if something goes terribly wrong. sarahm@Cadence.COM bungie cords - you never know when you might want to get that set of six beer mugs as a souvenir and transport it on the back of your bike. cathyf@is.rice.edu (Catherine Anne Foulston) ZAP Sport Towel. I think it is really useful because you can get it wet and it still dries you. =========================================================================== Cycling Myths Following are various myths about cycling and why they are/aren't true. Myth: Wearing a helmet makes your head hotter than if you didn't wear one. Actual measurements under hard riding conditions with ANSI standard helmets show no consistent temperature difference from helmetless riders. Part of the reason is that helmets provide insulated protection from the sun as well as some airflow around the head. (Les Earnest Les@cs.Stanford.edu) Myth: You need to let the air out of your tires before shipping your bike on an airplane - if you don't, the tires will explode. Assume your tire at sea level, pumped to 100 psi. Air pressure at sea level is (about) 15psi. Therefore, the highest pressure which can be reached in the tire is 100+15=115psi. Ergo: There is no need to deflate bicycle tires prior to flight to avoid explosions. (Giles Morris gilesm@bird.uucp) Addendum: The cargo hold is pressurized to the same pressure as the passenger compartment. (Tom ? tom@math.ufl.edu) Myth: You can break a bike lock with liquid nitrogen or other gases Freon cannot cool the lock sufficiently to do any good. Steel conducts heat into the cooling zone faster than it can be removed by a freeze bomb at the temperatures of interest. Liquid nitrogen or other gasses are so cumbersome to handle that a lock on a bike cannot be immersed as it must be to be effective. The most common and inconspicuous way to break these locks is by using a 4 inch long 1 inch diameter commercial hydraulic jack attached to a hose and pump unit. (Jobst Brandt jobst_brandt%01@hp1900.desk.hp.com) [More myths welcome!] =========================================================================== Buying a Bike One thing to decide before buying a bike is what type to buy. Here's a brief list: Road bike Once known as a "ten-speed", most are now 12 or 14 (or even 16) speed. There are several sub-types: racing, sport, and touring, the difference mostly in frame geometry. ATB All-terrain bike, also known as mountain bike. Great for riding in the dirt, these bikes usually have fat, knobby tires for traction in dirt and gravel. Hybrid A bike that borrows from road bikes and ATBs. For example, they have the light frame and 700c wheels of road bikes and fat knobby tires, triple cranks, wide-range derailleurs, flat handlebars and cantilever brakes from mountain bikes. Bike buying hints When you're ready to buy a bike, you should first decide what you want to use the bike for. Do you want to race? Do you want to pedal along leisurely? Do you want to ride in the dirt? Next, you should decide on a price range. Plan to spend at least $350 for a decent quality bike. Now find a good bike shop. Ask friends who bike. Ask us here on the net. Chances are, someone here lives in your area and can recommend a shop. Now that you are ready to look for a bike, visit the shop(s) you have selected. Test ride several bikes in your price range. How does it feel? Does it fit you? How does it shift? Does it have the features you are looking for? How do the shop personnel treat you? Remember that the shop gets the bike disassembled and has to spend a couple of hours putting it together and adjusting things, so look for sloppy work (If you see some, you may want to try another shop). You might want to try a bike above your price range to see what the differences are (ask the salesperson). Ask lots of questions - pick the salesperson's brain. If you don't ask questions, they may recommend a bike that's not quite right for you. Ask about places to ride, clubs, how to take care of your bike, warranties, etc. Good shops will have knowledgable people who can answer your questions. Some shops have free or low-cost classes on bike maintenance; go and learn about how to fix a flat, adjust the brakes and derailleurs, overhaul your bike, etc. Ask your questions here - there are lots of people here just waiting for an excuse to post! Make sure that the bike fits you. If you don't, you may find that you'll be sore in places you never knew could be so sore. For road bikes, you should be able to straddle the top tube with your feet flat on the ground and still have about 1 inch of clearance. For mountain bikes, give yourself at least 2-3 inches of clearance. You may need a longer or shorter stem or cranks depending on your build - most bikes are setup for "average" bodies. The bike shop can help you with adjustments to the handlebars and seat. Now that you've decided on a bike, you need some accessories. You should consider buying a helmet a frame pump a tube repair kit tire levers (plastic) a pressure gauge a seat pack (for repair kit, wallet, keys, etc) gloves a water bottle and cage a lock The shop can help you select these items and install them on your bike. =========================================================================== Chains Lubricating Chains Lubricating chains is a somewhat religious issue. Some advocate oil, some Teflon-base lubricants, some paraffin wax. The net majority favors a lubricant that does not leave an oily coating on the chain that can attract dirt, which will hasten chain/chainring/freewheel sprocket wear. If you want to use paraffin wax, make sure you melt the wax in a double boiler! Failure to do so can lead to a fire. You can use a coffee can in a pan of boiling water if you don't want to mess up good cookware. After the wax has melted, put the chain in the wax and simmer for 10 minutes or so. Remove the chain, hang it up, and wipe the excess wax off. Let it cool and reinstall on your bike. When using a liquid lubricant, you want to get the lube onto the pins inside the rollers on the chains, not on the outside where it does little good. Oilers with the narrow tubes are good for this because you can put the lube where you want it. Work the oil into the chain after applying it, wipe the chain off, and reinstall on your bike. --------------------------------------------------------------------------- Wear and Gear Slippage (Jobst Brandt jobst_brandt@hplabs.hp.com) There seems to be a lot of speculation on what makes chains wear and how to lubricate a chain. There are a number of ways to take care of a chain. Some traditional methods are the most damaging to chain life and others work to prolong life. As was mentioned on the net, chains don't stretch in the sense that the metal elongates, but the parts wear. Wear in the pins and sleeves change the length of the chain as the pins fit more loosely. The wear arises primarily from road grit that enters the chain when it is oiled. Grit on the outside of a chain looks bad but it has no effect on the function because it can't get inside to do damage. Only when a dirty chain is oiled does this grit get to the place where it can cause damage. Note that commercial abrasive grinding paste is made of oil and silicon dioxide (sand) and silicon carbide (sand). You couldn't do a better job if you tried to destroy a chain than to oil a road dirt (previously oiled) encrusted chain. Primitive rule #1: Never oil a chain on the bike. This means you should clean the grit off the chain before oiling it. Because this is essentially impossible without submerging the chain in a solvent bath (kerosene or commercial solvent), you must take the chain off the bike. The fine grit can only be removed from the interior of the chain in liquid suspension. A good example of this can be seen by using a Vetta (on the bike) chain cleaner and subsequently cleaning the same chain in a solvent bath. The best grit remains until last and there's plenty of it. Removing the solvent from the chain after the rinse is important. Compressed air is not readily available in the household nor is a centrifuge. You can go outdoors and sling the chain around. This works best if the chain is a closed loop. You don't have to press the pin completely in for this. The other way is to evaporate it. You should probably avoid accelerated drying methods because they could be explosive. The hot gear lube method works but it also acts as efficient fly paper, collecting plenty of grime between cogs. Motor oil is good but motorcycle chain lubes are better because they have volatile solvents that allow good penetration for relatively viscous lubricant. Paraffin is useless because it is not mobile and cannot replenish the bearing surface once it has been displaced. Sedisport The Sedisport chain, although the strongest and one of the lightest chains, achieves its light weight at the expense of durability. This chain has omitted the sleeve that on most roller chains supports the roller on its outside and furnishes the bearing for the pin on the inside. Normally the inside of the sleeve is well protected against lubricant depletion because both ends are covered by closely fitting side plates. In the Sedisport there is no sleeve and the formed side plates support the roller and pin with a substantial central gap. In the wet, lubricant is quickly washed out of pin and roller and the inferior bearing for the pin and roller often gall and bind. In good weather this is not a problem. Because this chain has feet of clay in the wet, Sedis re-introduced their earlier 5 element conventional chain, calling it a "chain for all seasons". The lightweight Regina chain goes one step farther and omits the pin, leaving the side plates to hinge directly on the sleeve. This gives them a knife edge bearing area that galls at the slightest lube depletion. Chain Life This is almost entirely a cleanliness and lubrication question rather than a load problem. The effect of load variations is insignificant when compared to the lube and grit effects for bicycles. The primary chains on motorcycles are operated under clean conditions and last years while the exposed rear chains must be replaced often. The only way to test whether a chain is worn is by measurement. The chain has a half inch pitch and, when new, has a pin at exactly every half inch. As the pins and sleeves wear this spacing increases and becomes damaging to sprockets. When the chain pitch grows over one half percent it is time for a new chain. At one percent chainring damage progresses rapidly. By holding a ruler along the chain on your bile, align an inch mark with a pin and see how far off the mark the pin is at twelve inches. An eighth of an inch (0.125) is the ten percent limit while more than a sixteenth is a prudent time to get a new chain. Skipping Chain When you put on a new chain, its pitch is exactly one half inch. A sprockets worn by a longer pitch chain pockets in its teeth. These pockets are formed by the rollers of a worn chain as they exit the sprocket under load. Rollers of a new chain with correct pitch exit under no load because the load is transferred to the next roller before disengagement. However, with hooked sprockets the new chain cannot engage under load because the pitch is too small to get over the hook and into the pocket. These differences are only a few thousandths of an inch but that is enough to prevent engagement when the previous roller is in its pocket. As a chain wears it concentrates more of its load on the last tooth of a sprocket before disengagement because its pitch no longer matches the pitch of the sprocket. This effect sometimes breaks off sprocket teeth. The load concentration on the sprocket also accelerates wear and is another reason to replace a chain at 1/16th inch wear. --------------------------------------------------------------------------- Adjusting Chain Length (Bob Fishell spike@cbnewsd.att.com) For all Shimano SIS and Hyperglide systems, the chain is sized by shifting to the smallest rear cog and the largest front sprocket, then sizing the chain so that the derailleur pulleys are on a vertical line, or as close as you can get to it. Note that this will result in the same chain length for any freewheel within the capacity of the derailleur, so it usually is not necessary to re-size the chain for a different cogset with these systems. The other rule I've used (friction systems) involves shifting to the largest chainring and the largest rear cog, then sizing the chain so that the pulleys are at a 45 degree angle to the ground. The rules probably vary from derailleur to derailleur. In general, you may use the capacity of the rear derailleur cage as a guideline. You want the chain short enough so the cage can take up the slack in the smallest combination of chainwheel and rear cog you will use. The chain must also be long enough so that the cage still has some travel in the largest combination you will use. For example, if you have a 42x52 crank and a 13x21 freewheel, the smallest combination you would use would be a 42/14 (assuming you don't use the diagonal). If the cage can take up the slack in this combo, it's short enough. If the cage has spring left when you are in the 52/19 combo (again, you are not using the diagonal), it's long enough. --------------------------------------------------------------------------- Hyperglide chains When you need to replace a Shimano Hyperglide chain, use a Sedis ATB chain. It's compatible with the Hyperglide system and doesn't need a special pin to put the chain back together when you take it apart. =========================================================================== Cranks and Bottom Brackets Bottom Bracket Info (Jobst Brandt jobst_brandt@hplabs.hp.com) The four kinds of BB threads in common use today are Italian, British, French, and Swiss, possibly in that order of occurrence. Diameter Pitch Right Left Cup -------- ----- ----- ----- Italian 36mm x 24F tpi right right tpi (threads per inch) British 1.370" x 24F tpi left right French 35mm x 1mm right right Swiss 35mm x 1mm left right Unless there is something wrong with the right hand cup it should not be removed but should be wiped clean and greased from the left side. The thread type is usually marked on the face of both left and right cups. Swiss threads are rare but if you have one it is good to know before attempting removal. --------------------------------------------------------------------------- Crank noises (Phil Etheridge phil@massey.ac.nz) I've had the creaky crank problem on every bike I've owned which has had cotterless cranks. Until now, I've never known a good solution to the problem. One suggestion I had was to replace the crank, but that wasn't something I was prepared to do on 1 month old bike under warranty. The shop mechanic spent half an hour with me and my bike sorting it out. Tightening the crank bolts and pedal spindle (i.e. onto the crank) didn't help (as Jobst will tell you). Removing each crank, smearing the spindle with grease and replacing the crank eliminated most of the noise. Removing each pedal, smearing grease on the thread and replacing it got rid of the rest of the noise. Greasing the pedal threads is a new one on me, but it makes a lot of sense, since they are steel and the crank aluminum. I thought it was worth relating this story, as creaky cranks seems to be quite a common problem. --------------------------------------------------------------------------- Cracking/Breaking Crankarms (Jobst Brandt jobst_brandt@hplabs.hp.com) [Ed note: Yes, another disputed issue is contained here - whether to lube the crank tapers before installing the crankarms. This has popped up from time to time on rec.bicycles, and has never been resolved one way or the other. The text here is Jobst's viewpoint.] Cranks break because they are aluminum and because they have high stress at various points. The worst of these points are at the pedal eye and where the spider fingers join the right crank. The pedal eye is a bad place because the joint is incorrectly designed, but since it is a standard, it may not be changed since it seems to work. This joint always moves and causes fretting corrosion and cracks. These cracks propagate into the crank and cause failure. A better joint here would be a 45 degree taper instead of a flat shoulder at the end of the pedal thread. The thin web between the spider and crank, another common crack origin on cranks like the Campagnolo Record, was nicely redesigned in the C-Record crank, but to make up for that the C-Record is otherwise weaker than the Record version. My experience is that they break in about 1500 miles because the pedal eye has a smaller cross section than the Record model, but maybe the alloy is poorer too. I have subsequently used Dura Ace cranks for more than two years with no failure yet. I don't believe in eternal life here either. Aluminum has no safe fatigue limit but just gets progressively safer as stress is reduced. In contrast, steel has a threshold below which failures cease. Therein lies some of the problem. As for cranks loosening, one can view the junction between spindle and crank in an exaggerated elastic model where the spindle is made of plastic and the crank of Rubbermaid household rubber. The crank, once properly installed and the retaining bolt in place, squirms on the square taper when under torque. During these deformations the crank can move only in one direction because the bolt prevents it from coming off. The crank always slides farther up the taper. Proof that the crank squirms is given by the fretting rouge always found on the spindle, whether lubricated or not, when a crank is pulled off after substantial use. As was mentioned by various observers, the left crank bolt is usually looser, after use, than the right one and this could be anticipated because the two cranks differ in their loading. This does not mean the left crank is looser. Actually it is tighter, only the bolt is looser. The left crank is more heavily loaded because it experiences offset twist from the pedal at the same time it transmits torque to the spindle. The right crank, being connected to the chain, experiences either spindle torque from the left pedal or twist from the right pedal but not torque and twist at the same time. In this squirming mode, cranks wander away from the retaining bolt and leave it loose after the first hard workout (for riders of more than 150 lbs). The bolts should NOT be re-tightened because they were correctly tight when installed. Cranks have been split in half from repeated follow-up tightening, especially left cranks. The spindle should be lubricated before installing cranks. A wipe of a mechanic's finger is adequate since this is to prevent galling in the interface. To prevent losing a loose crank bolt, the "dust" cover that is in fact the lock cap should be installed. Those who have had a crank spindle break, can attest to the greater stress on the left side because this is the end that always breaks from fatigue. A fatigue crack generally has a crystalline appearance and usually takes enough time to develop that the face of the fracture oxidizes so that only the final break is clean when inspected. Because a notch acts to concentrate stress, the advancing crack amplifies this effect and accelerates the advance once the crack has initiated. I have heard of instructions to not lubricate spindles before installing cranks but I have never been able to find it in any manufacturer's printed material. Although I have broken many Campagnolo cranks, none has ever failed at the spindle. I am certain that the standard machine practice of lubricating a taper fit has no ill effects. I have also never had a crank come loose nor have I re-tightened one once installed. --------------------------------------------------------------------------- Biopace chainrings Biopace chainrings have fallen into disfavor in recent years. They are hard to "pedal in circles". The early Biopace chainrings were designed for cadences of around 50-70 rpm, while most recommend a cadence of 80-100 rpm. Newer Biopace chainrings are less elliptical, but the general consensus is to (if you are buying a new bike) get the dealer to change the chainrings to round ones. =========================================================================== Tires and tubes Snakebite flats Snakebite flats are usually caused by the tire and tube being pinched between the road and the rim, causing two small holes in the tube that look like a snakebite. The usual causes are underinflation, too narrow a tire for your weight, or hitting something (rock, pothole) while having your full weight on the tire. The obvious solutions are to make sure your tires are inflated properly, use a larger size tire if you weigh a lot, and either avoid rocks and potholes or stand up with your knees and elbows flexed (to act like shock absorbers) when you go over them. --------------------------------------------------------------------------- Blown Tubes (Tom Reingold tr@samadams.princeton.edu) Charles E Newman writes: $ Something really weird happened at 12:11 AM. My bike blew a $ tire while just sitting parked in my room. I was awakened by a noise $ that scared the livin ^&$% out of me. I ran in and found that all the $ air was rushing out of my tire. How could something like happen in the $ middle of the night when the bike isn't even being ridden? I have $ heard of it happening when the bike is being ridden but not when it is $ parked. This happened because a bit of your inner tube was pinched between your tire bead and your rim. Sometimes it takes a while for the inner tube to creap out from under the tire. Once it does that, it has nothing to keep the air pressure in, so it blows out. Yes, it's scary. I've had it happen in the room where I was sleeping. To prevent this, inflate the tire to about 20 psi and move the tire left and right, making sure no part of the inner tube is pinched. --------------------------------------------------------------------------- Mounting Tires (Douglas Gurr dgurr@daimi.aau.dk) A request comes in for tyre mounting tricks. I suspect that this ought to be part of the FAQ list. However in lieu of this, I offer the way it was taught to me. Apologies to those for whom this is old hat, and also for the paucity of my verbal explanations. Pictures would help but, as always, the best bet is to find someone to show you. First of all, the easy bit: 1) Remove the outer tyre bead from the rim. Leave the inner bead. Handy hint. If after placing the first tyre lever you are unable to fit another in because the tension in the bead is too great then relax the first, slip the second in and use both together. 2) Pull out the tube finishing at the valve. 3) Inspect the tube, find the puncture and repair it. Now an important bit: 4) Check tyre for thorns, bits of glass etc - especially at the point where the hole in the tube was found. and now a clever bit: 5) Inflate the tube a _minimal_ amount, i.e. just sufficient for it to hold its shape. Too much inflation and it won't fit inside the tyre. Too little (including none at all) and you are likely to pinch it. More important bits: 6) Fit the tube back inside the tyre. Many people like to cover the tube in copious quantities of talcum powder first. This helps to lubricate the tyre/tube interface as is of particular importance in high pressure tyres. 7) Seat the tyre and tube over the centre of the rim. 8) Begin replacing the outer bead by hand. Start about 90 degrees away from the valve and work towards it. After you have safely passed the valve, shove it into the tyre (away from the rim) to ensure that you have not trapped the tube around the valve beneath the tyre wall. Finally the _really_ clever bit: 9) When you reach the point at which you can no longer proceed by hand, slightly _deflate_ the tube and try again. Repeat this process until either the tyre is completely on (in which case congratulations) or the tube is completely deflated. In the latter case, you will have to resort to using tyre levers and your mileage may vary. Take care. and the last important check: 10) Go round the entire wheel, pinching the tyre in with your fingers to check that there is no tube trapped beneath the rim. If you have trapped the tube, deduct ten marks and go back to step one. Otherwise .... 11) Replace wheel and reinflate. --------------------------------------------------------------------------- More Flats on Rear Tires (Jobst Brandt jobst_brandt%01@hp1900.desk.hp.com) Most sharp obstacles except tetrahedral glass slivers and puncture vine gets stuck more often is that the front tire upsets the sharp object just in time for the rear tire to catch it head-on. This front to rear effect is also true for motor vehicles. Nails lying on the road seldom enter front tires. When dropped on the road by a moving vehicle, the nail slides down the road aligning itself pointing toward traffic because it tends to roll around until it is head first. The tire rolls over it and tilts it up so that if the speed is ideal, the rear tire catches it upright. I once got a flat from a one inch diameter steel washer that the rear tire struck on edge after the front tire flipped it up. When it is wet glass can stick to the tire even in the flat orientation and thereby get a second chance when it comes around again. To add to this feature, glass cuts far more easily when wet as those who have cut rubber tubing in chemistry class may remember. A wet razor blade cuts latex rubber tubing in a single slice while a dry blade only makes a nick. --------------------------------------------------------------------------- Anodized vs. Non-anodized Rims (Jobst Brandt jobst_brandt@hplabs.hp.com) There are several kinds of dark coatings sold on rims. Each suggests that added strength is achieved by this surface treatment while in fact no useful effects other than aesthetic results are achieved. The colored rims just cost more as do the cosmetically anodized ones. The hard anodized rims do not get stronger even though they have a hard crust. The anodized crust is brittle and porous and crazes around spoke holes when the sockets are riveted into the rim. These cracks grow and ultimately cause break-outs if the wheel is subjected to moderate loads over time. There is substantial data on this and shops like Wheelsmith, that build many wheels, can tell you that for instance, no MA-2 rims have cracked while MA-40 rims fail often. These are otherwise identical rims. Hard anodizing is also a thermal and electrical insulator. Because heat is generated in the brake pads and not the rim, braking energy must cross the interface to be dissipated in the rim. Anodizing, although relatively thin, impedes this heat transfer and reduces braking efficiency by overheating the brake pad surfaces. Fortunately, in wet weather, road grit wears off the sidewall anodizing and leaves a messy looking rim with better braking. Anodizing has nothing to do with heat treatment and does not strengthen rims. To make up for that, it costs more. --------------------------------------------------------------------------- Clinchers vs. Tubulars (F.J. Brown F.Brown@massey.ac.nz) D.H.Davis@gdt.bath.ac.uk gave some useful hints on mounting clinchers, mostly involving the use of copious quantities of baby powder, and trying to convince me that clinchers aren't difficult to mount, so ease of mounting isn't a valid reason for preferring tubulars. wernerj@lafcol.lafayette.edu wrote that although average tubulars ride 'nicer' than average clinchers, there are some clinchers around that ride just as 'nice'. He also said that ease of change isn't a good reason for preferring tubulars as if you flat in a race, you're either going to swap a wheel or drop out. He pointed out that tubulars end up costing $20 - $80 per flat. ershc@cunyvm.cuny.edu gave some of the historic reasons that tubulars were preferred: higher pressures, lower weight, stronger, lighter rims. Said that only a few of these still hold true (rim strength/weight, total weight), but he still prefers the 'feel' of tubulars. leka@uhifa.ifa.hawaii.edu started this thread with his observations on clinchers seperated from their rims in the aftermath of a race crash. stek@alcvax.pfc.mit.edu comments on improperly-glued tubulars posing a threat to other racers by rolling off, and noted that this couldn't happen with clinchers. jobst_brandt@hplabs.hp.com agreed with stek, with the additional note that it is inadequate inflation that often allows tubulars to roll. Kevin at Buffalo agreed with stek and jobst about tubulars (improperly or freshly glued) sometimes rolling. ruhtra@turing.toronto.edu says he uses clinchers for cost and convenience. Clinchers let him carry around a tiny patch kit and some tyre irons, costing 60c, whereas tubulars would require him to carry a whole tyre, and would cost more. CONCLUSIONS: THE CLINCHER VS. TUBULAR WAR Tubulars - used to be capable of taking higher pressures, had lower weight and mounted onto stronger, lighter rims than clinchers. Clinchers have now largely caught up, but many cyclists thinking hasn't. Tubular tyre + rim combination still lighter and stronger. - are easier to change than clinchers. This matters more to some people than others - triathletes, mechanical morons and those riding in unsupported races. - cost megabucks if you replace them every time you puncture. ***However*** (and none of the North Americans mentioned this) down here in Kiwiland, we ***always*** repair our punctured tubulars (unless the casing is cut to ribbons). The process doesn't take much imagination, you just unstitch the case, repair the tube in the normal manner using the thinnest patches you can buy, stitch it back up again and (the secret to success) put a drop of Superglue over the hole in the tread. - can roll off if improperly glued or inflated. In this case, you probably deserve what you get. Unfortunately, the riders behind you don't. Clinchers - can be difficult to change (for mechanical morons) and are always slower to change than tubulars. Most people still carry a spare tube and do their repairs when they get home. - are cheaper to run: if you puncture a lot clinchers will probably still save you money over tubulars, even if you repair your tubulars whenever possible. Tubulars are only repairable most of the time, you virtually never write off a clincher casing due to a puncture. - have improved immensely in recent years; top models now inflate to high pressures, and are lighter and stronger than they used to be. Likewise clincher rims. Some debate over whether tubulars are still lighter and tubular rims stronger. Probably depends on quality you select. No doubt that high quality clinchers/rims stronger, lighter and mor dependable than cheap tubular/rim combination. --------------------------------------------------------------------------- Presta Valve Nuts (Jobst Brandt jobst_brandt@hplabs.hp.com) Two points here: 1. The jamb nut holds the stem when pumping so that it does not recede into the rim when pressing the pump head against the tire. This is especially useful when the tire is flat (after installing the tube). It also keeps the stem from wiggling around while pumping. I have not had difficulty in removing the nut over these many years of bicycling. When hands are very cold this is a problem, but then so is everything else. Just opening the valve nut on a Presta valve can be difficult under such conditions. 2. Breaking off stems while using a frame pump is a misunderstanding of the concept. I find new tubes along the roadside with broken off stems. The pump head is to be held in the fist and pumping force is supposed to be between the hands, not the hand and the rim. To practice this action take the pump in hand with the thumb over the outlet and pump vigorously letting no air out. No net force should escape since there is no other body involved. This is essentially what should take place when pumping a tire. That the some of the people who do not grasp this concept have deficient thinking is proved by their discarding the evidence along the road. They also have no concept of blatant littering for which there are large fines in this area. They probably think it serves the stupid tube right for breaking off. I think otherwise. It is unfortunate that bike shops do not instruct new bike owners about the use of the frame pump and some tire patch hints like don't try to ride a freshly patches tube, carry a spare and always use the spare after patching the current tube. I think we covered that extensively here earlier. If it isn't in the FAQ it should be. --------------------------------------------------------------------------- Ideal Tire Sizes (Jobst Brandt jobst_brandt@hplabs.hp.com) > I'm getting a custom frame built and wondered what > people thought of using 26 inch road wheels. Smaller > wheels ought to be lighter and stronger. and goes on to list advantages and disadvantages, most of which are less that important in deciding what size to use. What in fact brought us the wheel size (700 or 27") that we have is better understood by the women riders who have a hard time fitting these wheels into their small bicycle frames. Wheels would be larger than they are if they would fit the average riders bike, but they don't. So the compromise size is what we are riding today. > It seems to me that the most obvious reason for using 27" > wheels is tradition, but I'm not sure the advantages make > it worth trying to swim upstream. What do you think? This line of thought is consistent with the "cost be damned" approach in bicycling today. The big bucks are spent by people who want the best or even better than their peers. The more special the better. Riders consistently spend nearly twice the money for wheels and get worse rims when they choose anodized ones, whether there is merit to this finish is of no interest. They cost more so they must be better. How "custom" can you get than to have wheels no one else on the block has (maybe 25"?). If enough riders ask for 24", 25" and 26" wheels, manufacturers will up the price as their product lines multiply and the total sales remain constant. Tires and spokes will follow as a whole range of sizes that were not previously stocked become part of the inventory. Meanwhile, bike frames will come in different configurations to take advantage of the special wheel sizes. SIzes whose advantages are imperceptibly small but are touted by riders who talk of seconds saved in their last club TT or while riding to work. A larger wheel rides better on average roads and always corners better because it brings a longer contact patch to the road. A longer contact averages traction over more pavement and avoids slip outs for lack of local traction. Visualize crossing a one inch wide glossy paint stripe with a 27" wheel and an 18" wheel when banked over in a wet turn. I see this subject arise now and then and it reminds me of the concept of splitting wreck.bike into several newsgroups. The perpetrators bring the matter up for many of the wrong reasons. Ride bike, don't re-invent what has been discarded. =========================================================================== Headsets, Forks Indexed Steering (Jobst Brandt jobst_brandt@hplabs.hp.com) > In the several years I spent working in a pro shop, I have never seen a > case of "index steering" (yes, we called it that) that was _not_ caused > by a "brinelled" headset - one with divots in the races. I am 99.999 > percent certain that that is your problem. What are you going to do if > you don't fix it? I suggest that you fix the headset even if you sell > the bike, as a damaged headset could be grounds for a lawsuit if the > buyer crashes. I disagree on two points. First, because the use of the term brinelling conveys a notion as incorrect as the phrase "my chain stretched from climbing steep hills" and second, because there is no possibility of injury or damage from an "indexed" head bearing. Damage to the head bearings seems to be twofold in this case because the steering, if properly adjusted, only gets looser from dimpled bearings and would not become arrested by the dimples. So the head was adjusted too tight or it got tighter inadvertently. However, dimpling is caused by lubrication failure and occurs while riding straight ahead. This condition is worsened by a tight bearing while a loose bearing would introduce more lubricant if it were to rattle. If you believe it comes from hammering the balls into the races, I suggest you try to cause some dimples by hammering with a hammer onto the underside of the fork crown of a clunker bike of your choice. Those who pounded in cotters on cottered cranks will recall no such dimpling on the BB axle and even though this is a far smaller bearing race than a head bearing and the blows are more severe and direct, no dimples were made. Ball bearings make metal-to-metal contact only when subjected to fretting loads (microscopic oscillations) while in the same position, as in riding straight ahead on a conventional road. If you watch your front axle while rolling down the road at 20+ mph you will notice that the fork ends vibrate fore and aft. This motion arises not at the blade tips but at the fork crown and articulates the head bearing in fretting motions that are not in the normal direction of bearing rotation. Any substantial steering motion replenishes lubrication from adjoining areas. Lubrication failure from fretting causes welding between the balls and races and these tiny weld spots tear out repeatedly. The result is that at the front and rear of the races elliptical milky dimples occur. Were these brinelling (embossed through force) they would be shiny and round. Various testimonials for the durability of one bearing over another may be based on good experience, however, the differences in most of these was not in the design of the bearing but rather the type of lubricant used. A ball bearing is not suitable for this use. This is in spite of their use in almost all bicycles. To reduce point loads and to protect the rolling elements from fretting motion, roller bearing head bearings have been built. In these the rotary motion is taken up in needle bearings on conical races and the fork articulation is absorbed by an approximation of a spherical cup (the steel race) against the aluminum housing. Both of these bearings are ideally loaded. The rollers all remain in contact and carry rotary motion while the plain spherical bearing remains in full contact carrying low pressure fore and aft motion. I am disappointed that roller bearings until now have not been suitably perfected to rid us of the age old bearing failure. Maybe some day soon Sun Tour, Campagnolo, Shimano or Stronglight will emerge with an easily adjustable and fully compatible bearing. The one I am using is durable but not easily adjusted and it has too great a stack height to qualify for a recommended replacement. =========================================================================== Brakes Center Pivot vs. Dual Pivot Brakes (Jobst Brandt jobst_brandt@hplabs.hp.com) Sidepull (one central pivot) brakes operate at a small angle to the rim. That means the pad moves in a nearly perpendicular direction to the braking surface and the pads can be completely worn down without adjusting their position. The unit is light and has a self contained quick release and cable adjustment feature. Its weakness is its thin arms that, in the pursuit of light weight, flex in the bending direction. With the current practice to minimize tire clearance on road bicycles, sidepull brakes cannot be used off road for lack of dirt clearance. Their return spring is anchored in a way that relative motion occurs between it and the brake arms. This motion demands lubrication and in its absence the brake does not center itself. This is a perpetual problem that has not been solved and has given rise to many designs, the latest of which is the Shimano dual pivot brake. This brake has the disadvantage that it cannot track a wobbly wheel because it is forced to be centered. The cantilever and centerpull brakes are inversions of the same design. Both have pivot points that are at 45 degrees to the brake surface, but the centerpull offers no advantage over sidepulls because it has all the same problems and not the advantages. In contrast the cantilever is the most rigid of available brakes and offers more tire clearance for off road use. The approach angel moves the brake pads in an undesirable direction so that as the pad wears it must be adjusted to prevent falling off the rim. With wear, the centerpull goes into the tire while the cantilever allows the pad to pop under the rim, never to return. Cantilever brakes have the additional problem that their reaction force spreads the forks. For this reason, U shaped stress plates are made to contain this force. For forks with telescopic suspension, braking restricts forks motion. Nearly all bicycle brakes have about the same mechanical advantage (4:1) that arises primarily in the hand lever. The "calipers" all approximate a 1:1 ratio. This is necessary to fit the reach of the average hand and the strength of the hand in proportion to body weight. That is to say all brakes are made to about the same human specification. Force and motion are a trade-off and this is the result. The Campagnolo Delta and Modolo Chronos brakes have a variable ratio that at the extremes ranges from infinity to zero, its motion being generated by an equilateral parallelogram that changes from one extreme to the other. This is an undesirable feature, especially as the pads wear and braking takes place in the zone of increased lever travel and increased mechanical advantage. The brake bottoms out abruptly. Servo activation on cantilever brakes has been offered in a design that uses the forward thrust on the brake post to add force to the application. Self servo effects are undesirable in brakes because the proportionality between braking and hand force is lost. You don't know how much braking you will get for a given hand lever force. It can vary widely and in some circumstances cause an unwanted skid. =========================================================================== Adjustments and Repairs Seat adjustments (Roger Marquis marquis@well.sf.ca.us) The following method of setting saddle height is not the only method around for setting your saddle height but it is the most popular among coaches and riders both here and in Europe. A) Adjust saddle level or very slightly nose up, no more than 2mm at the nose. B) Put on the shoes you normally ride in. Have wrench ready (usually a 5mm Allen). C) Mount the bike and sit comfortably, leaning against a wall. Hold the brake on with one hand (or mount the bike on a turbo trainer if you have one). D) Place your HEELS on the pedals, opposite the clip, pedal backwards at 30+ rpm without rocking your pelvis (very important). E) Adjust seat height so that there is about: 1) ZERO TO ONE HALF CM. for recreational riders (-50 mi/wk.), 2) ONE HALF TO ONE CM. for experienced riders (50+ mi./wk.), 3) ONE TO TWO CM. for endurance cyclists (250+ mi./wk.), between your heel and the pedal. If your soles are thicker at the cleat than at the heel adjust accordingly. Don't forget to grease the seat post. F) Ride. It may take a couple of rides to get used to the feel and possibly stretch the hamstrings and Achilles slightly. --------------------------------------------------------------------------- Cleat adjustments (Roger Marquis marquis@well.sf.ca.us) [Ed note: You may also want to consider going to a bike shop that does Fit Kit and have them do the Fit Kit RAD to adjust your cleats. Many people recommend it.] A) Grease the cleat bolts and lightly tighten. B) Sitting on the bike, put your feet in the pedals and adjust until: B1) The ball of your foot is directly above or, more commonly, slightly behind the pedal axle and: B2) There is approximately 1 cm. (1/2in.) between your ankle and the crank arm. C) Tighten the cleat bolts 80% and go out for a ride. If another position feels more comfortable rotate your foot into that position. D) Carefully remove your shoes from the pedals and tighten the bolts fully. If you cannot get out of the pedals without shifting the cleats leave your shoes on the bike and draw an outline around the cleat. --------------------------------------------------------------------------- SIS Adjustment Procedure (Bob Fishell spike@cbnewsd.att.com) Shimano's instructions for adjusting SIS drivetrains varies from series to series. The following method, however, works for each of mine (600EX, 105, and Deore'). [Ed note: Works on Exage road and mtb also.] Your chain and cogs must be in good shape, and the cable must be free of kinks, slips, and binds. The outer cable should have a liner. clean and lubricate all points where the cable contacts anything. SIS adjustment: 1) Shift the chain onto the largest chainwheel and the smallest cog, e.g., 52 and 13. 2) WITHOUT TURNING THE CRANKS, move the shift lever back until it clicks, and LET GO. This is the trick to adjusting SIS. 3) Turn the crank. If the chain does not move crisply onto the next inside cog, shift it back where you started, turn the SIS barrel adjuster (on the back of the rear derailleur) one-half turn CCW, and go back to step 2. Repeat for each pair of cogs in turn until you can downshift through the entire range of the large chainwheel gears without the chain hesitating. If you have just installed or reinstalled a shift cable, you may need to do this several times. 4) Move the chain to the small chainring (middle on a triple) and the largest cog. 5) turn the cranks and upshift. If the chain does not move crisply from the first to the second cog, turn the SIS barrel adjuster one-quarter turn CW. If the drivetrain cannot be tuned to noiseless and trouble-free SIS operation by this method, you may have worn cogs, worn chain, or a worn, damaged, or obstructed shift cable. Replace as needed and repeat the adjustment. =========================================================================== Tools and Workstands Where to buy tools You can buy tools from many sources. Some tools can be purchased at your local hardware store (wrenches, socket sets, etc), while the special bike tools can be purchased from your local bike store or one of the mail order stores listed elsewhere. You can buy every tool you think looks useful, or just buy the tools you need for a particular repair job. Buying the tools as you need them will let you build up a nice tool set over time without having to drop a lot of money at once. Some common tools you will need are: Metric/SAE wrenches for nuts and bolts (or an assortment of adjustable wrenches). Screwdrivers, both flat and phillips. Metric allen wrenches. Pliers. Wood or rubber mallet for loosening bolts. Special tools and their uses: Cone wrenches to adjust the hub cones. Chain tool to take the chain apart for cleaning and lubrication, and to put it back together. Tire irons for removing tires. Spoke wrenches for adjusting spokes. Cable cutters for cutting cables (don't use diagonal pliers!). Crankarm tools for removing crankarms. Bottom bracket tools for adjusting bottom brackets. Headset wrenches to adjust the large headset nut. --------------------------------------------------------------------------- Workstands There are a variety of workstands available, from about $30 to over $130. Look at the mail order catalogs for photos showing the different types. The type with a clamp that holds one of the tubes on the bike are the nicest and easy to use. Park has a couple of models, and their clamp is the lever type (pull the lever to lock the clamp). Blackburn and Performance have the screw type clamp (screw the clamp shut on the tube. If you have a low budget, you can use two pieces of rope hanging from the ceiling with rubber coated hooks on the end - just hang the bike by the top tube. This is not as steady as a workstand, but will do an adequate job. =========================================================================== Riding Techniques Descending I (Roger Marquis marquis@well.sf.ca.us) Descending ability, like any other skill, is best improved with practice. The more time you can spend on technical descents the more confidence and speed you will be able to develop. A few local hot shots I know practice on their motorcycles before races with strategic descents. While frequent group rides are the only way to develop real bike handling skills descending with others will not necessarily help you descend faster alone. The most important aspect of fast descending is relaxation. Too much anxiety can narrow your concentration and you will miss important aspects of the road surface ahead. Pushing the speed to the point of fear will not help develop descending skills. Work on relaxation and smoothness (no sudden movements, braking or turning) and the speed will follow. A fast descender will set up well in advance of the corner on the outside, do whatever braking needs to be done before beginning to turn, hit the apex at the inside edge of the road, finally exiting again on the outside (always leaving some room for error or unforeseen road hazard). The key is to _gradually_ get into position and _smoothly_ follow your line through the corner. If you find yourself making _any_ quick, jerky movements take them as a sign that you need to slow down and devote a little more attention further up the road. Use your brakes only up to the beginning of a corner, NEVER USE THE BRAKES IN A CORNER. At that point any traction used for braking significantly reduces the traction available for cornering. If you do have to brake after entering the curve straighten out your line before applying the brakes. If the road surface is good use primarily the front brake. If traction is poor switch to the rear brake and begin breaking earlier. In auto racing circles there are two schools of thought on braking technique. One advocates gradually releasing the brakes upon entering the corner, the other advises hard braking right up to the beginning of the curve and abruptly releasing the brakes just before entering the curve. A cyclists would probably combine the techniques depending on the road surface, rim trueness, brake pad hardness and the proximity of other riders. Motorcyclists and bicyclists lean their bikes very differently in a corner. When riding fast motorcyclists keep their bikes as upright as possible to avoid scraping the bike. Bicyclists on the other hand lean their bikes into the corner and keep the body upright. Both motorcyclists and bicyclists extend the inside knee down to lower the center of gravity. To _pedal_ through the corners make like a motorcyclists and lean the bike up when the inside pedal is down. One of the most difficult things about descending in a group is passing. It is not always possible to begin the descent ahead of anyone who may be descending slower. If you find yourself behind someone taking it easy either hang out a safe distance behind or pass very carefully. Passing on a descent is always difficult and dangerous. By the same token, if you find yourself ahead of someone who obviously wants to pass, let them by at the earliest safe moment. It's never appropriate to impede someone's progress on a training ride whether they are on a bicycle or in a car. Always make plenty of room for anyone trying to pass no matter what the speed limit may be. Be courteous and considerate and you'll be forever happy. Remember that downhill racing is not what bicycle racing is all about. There is no need to keep up with the Jones'. This is what causes many a crash. Compete against yourself on the descents. Belgians are notoriously slow descenders due to the consistently rainy conditions there. Yet some of the best cyclists in the world train on those rainy roads. Don't get caught pushing it on some wet or unfamiliar descent. Be prepared for a car or a patch of dirt or oil in the middle of your path around _every_ blind corner no matter how many times you've been on a particular road. Take it easy, relax, exercise your powers of concentration and hammer again when you can turn the pedals. If you're interested in exploring this further the best book on bike handling I've read is "Twist of The Wrist" by motorcycle racer Keith Code. There is also data out there (Cycle Magazine) on eye exercises designed to train depth perception adjustment, peripheral vision and concentration. If you know where I can find this information please send it to: NCNCA District Coaching Office Roger Marquis 782 San Luis Rd. Berkeley, Ca 94707 ---