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Ask the Mechanic
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Read the Ask the Mechanic Disclaimer
Stuck in gear and need expert advice? Ask Andy the Mechanic (a.k.a. Andy Wallen), the proprietor of Wheelcraft Bicycles of Wheeling, WV. (Please, no old bike & antique questions.) E-mail to firstname.lastname@example.org, subject "ask the mechanic," or mail your question directly to Ask the Mechanic, c/o Wheelcraft Bicycles, 2185 National Road, Wheeling, WV, USA 26003. Andy will e-mail your advice and we may post it afterward. Take a look at our back issues to find answers to all kinds of bike fix-it questions.
Bike Mechanics Should Always Have a Handy Copy of ...
Bicycling Magazine's Complete Guide to Bicycle Maintenance and Repair
by Jim Langley, May 1999 OR...
Zinn and the Art of Road Bike Maintenance
by Leonard Zinn, April 2000 OR...
Zinn and the Art of Mountain Bike Maintenance
by Leonard Zinn, February 1998.
Fall 2000 Questions & Answers ...
I want to re-space a 9-speed Shimano mountain cassette and use it on my Campy setup. I have seen it done in Cycle Sport, Nov. 1999, Page 43. Do you know where I can have this done?
I don't usually read Cycle Sport, so I'm not real sure what they did or why. If you want "megarange" gearing, your rear der will not do it. Stock Shimano 9-speed cassettes (MTB) have either 32 or 34 teeth on the biggest sprocket; Campy ders top out at 28 teeth. If you want a 28 tooth low, it would be much easier to just buy a 13-28 exa drive cassette than to play around with the Shimano cassette. In other words, 28 is the lowest gear that will work well. You might add some chain, or be real careful with your shifting and use 32 teeth, but your equipment is not designed to stretch this far.
I'm well aware that stuff works all the time when manufacturers tell us that they won't, but usually there's a reason that they specify things like the limits of cog capacity and maximum chain wrap. Also, you must use a Shimano hub, as Campy freehubs are 1.8 mm larger in diameter.
Now that we've established that this is not a recommended procedure, doing it should be fairly simple. The Shimano cassette comes apart by removing 3 little allen screws that extend from the 7th to the 1st cog. I'm not sure if or how the required spacers and cogs will fit, but 2.8mm Campy spacers are widely available. Shimano cassettes use 2.56 mm spacers, so you're going to wind up 1.92mm short, which I suppose could be made up with a 2mm spacer. You're also going to come up .27mm short due to the thinner Shimano cogs, so the 2mm spacer on the inside of the cassette will probably get you close enough.
Close enough is about all you can expect here: it's never going to shift like either a complete Campy or Shimano drivetrain. The 8th and 9th cogs have built in spacers, so you'll need to get two .24mm (or close enough) spacers. I guess what it comes down to is trying to maintain the cog center spacing, and the 2.8mm spacers with the Shimano cogs will get you real close (within .03mm). If you accept the fact that this probably won't work well, and your rear der is not going to like cogs over 28 teeth, I probably have the required spacers in stock, and, unless machining is required, I can do the job for you.
I would like a little more detail as to what size and brand of spacers these guys used, and what they did about the der. capacity.
I have a Super Record crank (180mm) with 42/53 chainrings. The rest of the bike is Dura-Ace (6-speed cassette 26 to 13). This is all in excellent shape on a custom built bike. I love the bike but I'm getting to old for such gearing and want to make it easier for touring. Can I get a smaller front chainring and will that help? Seems replacing the front crank/chainrings is the cheapest and I keep everything else I have.
Next solution I was told was go to a triple but that means replacing almost everything to be compatible. I'm lost on what to do. Also, how do you determine your crank's bolt circle/pattern to determine what chainrings will fit?
All Campy cranks that I know of use a 135mm bolt circle. You can readily find 39-tooth chainrings, and probably even a 38. Going to a 39 would make a significant difference. I assume that you have a freewheel, not a cassette, and you can only get good freewheels from SRAM (formerly Sachs). By changing the freewheel to a 13-28 and changing the chainring to a 39, you should be able to climb most anything, with a minimum of hassle and expense. The triple option will involve a new crank, front and rear ders, and probably a bottom bracket, so that would be a last resort. You may be able to use a 7 speed freewheel to smooth out the gaps.
My name is Anthony Browne and I am currently in my final year in college, studying mechanical engineering. My current project is on finite element analysis. The component that I have chosen to analyze is the crank arm of a bicycle. I was wondering if maybe you could send me any information regarding the material properties of any type of crank such as max. yield stress, young's modulus or the exact type of alloy that is used. I am also looking for a drawing with dimensions of a crank and would be most grateful if you could send me any information regarding the above or of any other web sites that you know where I could get this information.
This is really out of my realm. There used to be some highly technical stuff published about bicycle parts, but I have little use for them, and have lost track of the publishers. I'm in retail, so basically, if you know that all the Shimano cranks are crap and there's a cheaper, lighter, stiffer way to do anything, just what are you going to do about it? So while it may be enlightening to know this stuff, it won't sell bikes, and it certainly won't cure Shimano addiction.
I don't have addresses, but look around for guys like Lenard Zinn (technical writer for Velonews). If you can get a hold of the right person, Cannondale does a lot of in-depth product testing, and if you want to look at alternatives to aluminum, check out Morati. If Bullseye is still in business, they can tell you about hollow cromo (as could Syncros, who recently dropped this item). Bullseye and Cannondale have been saying that hollow is better for years, and now Shimano seems to agree.
Sorry I can't help you more,
I have a problem finding rear shock bushings for dbr v6 and v3.1. I have contacted a couple of dealers with no luck, even called Diamondback. They offer a bushing kit and it contains all but what I want. The 3.1 has a Rock Shox deluxe and the v6 has a helix air. any thoughts would be good. I'm ready to retire these bikes because of a 30-cent plastic bushing. Enjoy
Diamondback is a company known for cheap bikes and poor, if any after-purchase product support. For these and other reasons, I have never seen the value of becoming a Diamondback dealer, and therefore, probably do not have access to these parts. I do have an account with db, and may be able to get them if they are available, but if you've already been to a couple of dealers, I doubt that I can help you as I don't even carry the bike. If they offer a frame bushing kit and it doesn't have what you need, maybe you are trying to get a shock bushing. Most shocks have 2 DU bushings which are pressed into the eyes, and the mounting hardware (little aluminum collars or washers) fit into these bushings.
Among Treks, Fishers, and various other full suspension bikes, I've replaced even numbers of frame bushings, which cost a lot more than 30 cents, and DU bushings, which also cost a lot more than 30 cents, and the DU bushings are obtained from the shock manufacturer, not the frame manufacturer.
If you need the frame bushings and can't get them, I would complain vehemently to db, and demand that if they can't supply you with a disposable part ( none of the aforementioned bushings will last more that 3 years of moderate riding), they should replace your frame every 3 years! Down with Derby (db, univega, raleigh, etc.)!
Please tell me the difference between "compact" and "standard" chainrings?
Compact chainrings are actually standard, as very few bikes come with the old standard size these days. The bolt circle for compact is 58mm (small ring)/94mm (middle and big ring), and the sizes range from 20 teeth to 46 (46 is a stretch, 42 or 44 works best). Standard size rings are currently only used on XTR drive trains. Standard bolt circles measure 74/110, and rings range from 24 to 48, possibly 50 teeth. You can't interchange them, and if you have a compact crank, you must use a compact front deraileur, and vice versa. If you need to replace chain rings nowadays, you need to know the bolt circle, how many teeth, and whether it is 4 or 5 arm spider.
What is the lowdown on figuring out what crank length I need? I am about 5'8" with a 29" inseam. Does it really matter if I have a 172.5 mm or a 175 mm crank? I am building up a couple of frames.
I'd suggest a 172.5, given the information given here. I don't think that there's a scientific method to figuring this out, and my personal opinion is that, like choosing between a 54 and a 55 or between a 16.5 and 17.5 frame (you can handle them both, but one works better for what you do), or 42cm Cinellis vs. 44cm ITMs, this is largely a matter of personal preference. It has been demonstrated that, using elite athletes in blind testing, longer cranks produce greater speed, and it would appear obvious to me that longer cranks are better for us untrained mashing climbers. Some of my customers who do triathlons like the shorter of two crank choices, I suppose for a smoother spin at higher rpms, but I usually prefer 175 or longer. I'd like to have a TT bike with 172.5s and a climber with 180s, but since I only have 1 road bike, I use 175s. I believe that someone with your dimensions should be considering 170 vs 172.5, and I would suggest 172.5 for all around use. Ideally, you should try both, and maybe even a 175, then decide. I'm sure that someone out there has a more formulaic approach to this, but I really think it all comes down to preference.
I have a one-of-a-kind bike with a tremendous front rake . The down tube angle makes the front fork stick out quite a ways from the bike and is a real bear to control if wheel is turned more then about 10 degrees from the center line. The bike has 26", wide tires. Would I gain anything if I put a thin 26" tire on the front. Thanks in advance for your thoughts.
Usually, skinnier tires have a lower profile, and may give you a little more room, but I doubt that your handling would improve very much. Standard geometry should not be monkeyed with very much; a degree here or there or a couple of millimeters here or there won't destroy things, but it sounds like you've gone too far!
I was wondering what you believe to be the best material for a road racing frame. I was also wondering--if you had a price range of $2000-$2500--which road bike you would personally get or from which company you would get it.?
I have been riding on and off for two years while entering a few 100-mile tours with an old Centurian Dave Scott Signature Series road bike, and now I want to get a new bike that fits into the price range mentioned above. But I am becoming quite flustered with all these different bikes and companies. In short I just want to know the best racing bike for the dollar. Any help would be greatly appreciated.
Frame selection is a personal matter, and there are thousands of opinions, and a few of them might be valid. Low-priced Ti frames (Mongoose, Samson, $1200 Litespeeds) are a gimmick, they capitalize on the ti mystique, and deliver a frame that may last forever, except for the Samson, and really not perform as well as a lower-priced steel (853 or Columbus tubing) frame.
I don't care for aluminum, as it has a very finite lifespan and yields a mostly uncomfortable ride. Aluminum has a powerful effect on test riders: they are impressed with the lightness and acceleration, due to the stiff rear triangle. If they rode it for two hours (on our roads, anyway), they would probably become aware of its downside--it'll beat you silly.
I personally ride a Lemond (Trek) OCLV carbon bike, and it has all the advantages of aluminum, with a pretty comfortable ride. I don't know if you can buy a Trek OCLV in your price range, but I think you can come close. The downside of this bike is that carbon is not a lifetime frame, and may not survive a crash.
For value, performance, and comfort, we like the Lemond Zurich. This is an 853 frame with a carbon fork and Rolf vector wheels, available with either Ultegra double or triple, for around $2000. Chuck the SPDs and replace them with Look pedals, and you'll have one of the best all around bikes available, and get change for your $2500. Some people like SPDs; I tolerate them. At the upper end of your budget, you may be able to outfit a similar Italian crafted frame with either Ultegra or Veloce, but this will cost more, and you won't get the nice wheels.
In a nutshell, aluminum is a disposable rough ride, cheap ti is a rip-off, and high quality steel is a good investment. If you want ti, spend over $3000 and you'll probably love it. If $2500 is your limit, buy the Zurich.
PS: On the budget ti issue, whatever you do, don't buy commi-chinese-prison-labor-built-cheap piece of crap owned by huffy airborne!
I would like to replace the cassette on my Shimano Ultegra freehub, but this is a pre-hyperglide freehub. I can't find pre-HG cassettes, and HG cassettes won't fit (although I understand they could be made to fit by grinding them down in one area). One solution that occurs to me is to replace the freehub body with a 7-speed HG freehub body. The only such body I have found is Shimano-LX. Do you think that will work? Would something else be better? Could you supply it?
It's possible to get an Ultegra 7-speed hyperglide body, but we only stock LX and XT bodies. The difference is negligible, usually only in the sealing mechanism, which can be made to work by switching dustcaps and such around. If you want everything perfect, you'll need to buy an axle set that matches your freehub body, but that is not absolutely necessary. I would hesitate to do this procedure, because if you have a pre-hyperglide wheel, it is probably not worth fixing, as the price of this repair would exceed the value of the wheel itself, and it is not likely that the rims and spokes are in primo condition. Of course, if you have something fancy and everything's in good shape, then why not fix it?
Just consider that a basic rear wheel is not going to cost much over $70, and your freehub body and other parts will cost about $30, and you'll still have an old rim with fatigued spokes. You can also put an 8/9 speed hub or freehub body (with 130mm OLD) on your bike if your rear dropouts are, or can be spread to, 130mm. A 7-speed cassette will fit on an 8-speed body with a 4.5mm spacer on the inside.
A 7-speed Ultegra body and axle set would
take about 7-10 days to get, and should cost about $40, and
7-speed cassettes go from $20-$40 depending
on size and quality.
I've been looking for a good steel road frame at a good price and came across a 1996 Colnago C98 here in Holland. I noticed a very slight (about 1 mm or so) gap where the lug at the bottom joins the seat tube. I was assured by the LBS that this was not a problem. But if it is a problem, is it repairable? The bike has about 25000 km, never raced or crashed, Shimano 105 all around (STI-8), Mavic open 4CD, and is selling for about $475.
Someone suggested the lug could easily be re-brazed, if there is a problem, but it would damage the paint job.
Thanks for any comments and suggestions what to look for on closer examination of this bike.
One big advantage of steel frames is the reparability, and I'm sure this one could be easily fixed. Matching a Colnago paint job would be difficult and very expensive. I would estimate less than $100 to fix, but several hundred to paint, so maybe you could just touch it up with rustoleum hot rod primer. I do wonder how this happened if the bike has never been crashed, though.
I have a Bridgestone model 550 Racing Series road bike which I like very much. Is it practical to put new Shimano Sora components on my bike? It now has Suntour index 6-speed with double chainring. I would like a triple. If this is possible, is it practical to do, and how much would it cost?
I have not seen the Sora components in catalogs. I have thought of buying a new bike but, as I said, I would really like to keep my trusty bike.
You may have to spread your rear dropouts to 130mm, but with a steel bike this is not a problem. Sora stuff is supposed to be available, but I've only seen it on complete bikes. Expect to pay around $450 for the group with built wheels, or $650 for the group with a frame, bars, seat, etc, thrown in.
Great web site! Just what the cycling junky needed!
Q: How do I adjust and set the indexing for Rapid fire shifters? Particularly, the front Der/shifters. I can't get the shifter to go to the next speed indicator in the window, or chain ring.
Check the Winter 2000 Ask the Mechanic column for complete front and rear der adjustments. You probably need a cable adjustment.
I bought two bicycles, one a road bike and the other a mountain bike. Both bicycles had directional tires with the front tire arrow mounted in the opposite direction. I have asked several people and I get conflicting answers. Which way does the arrow go on the front wheels? Does it really matter? I have spot checked some new bikes in different stores and see tires mounted in both directions.
Steve in NC
Different tyres have different directional directions, so I can't speak for all manufacturers. In general, if the front and rear tyres are to be mounted differently, it should say so; otherwise, arrows should point to the front. If no arrows are present, mount the label on the right side of the wheel. Some tyres are obviously directional, and others say they are, but probably don't function better or worse regardless of the direction.
First of all, thank you for this service. Living in a rural area does not give me access to many bicycle mechanics. I have an '89 Schwinn Circuit road bike that needs some upgrading. I would like to replace the 7-speed cassette that is on there now (it came with a 6-speed). Is this bicycle compatible with the newer 8-speed or 9-speed cassettes? If so, what special treatment, if any, is necessary?
Thank you very much,
You should count on buying all new stuff for everything to work well. 8-speed road equipment has become scarce as of late, so I'd recommend going 9. You can buy a Sora 8-speed group for about $400 (no wheels), or a 9-speed Tiagra group for about $100 more. If this is a decent bike, you may want to go up-line to 105 or Ultegra.
I have a Pacific Riptide 21-speed mountain bike, but haven't been able to ride it much because of a problem that I hope you can help me with.
While pedaling, my bike keeps jumping gears. Any idea why and how to fix it? Maybe new cables? Any help would be appreciated.
If you've ridden a Pacific for any length of time, you are lucky to be alive, let alone any minor inconveniences. You could have any of several problems, but I'd check the chain for stuck links first, then look at your cable housings and cables. It could be a loose cable, or defective freewheel/cassette.
I have a squeaking/creaking problem. I have one of those coda cranksets that has all three rings as a separate piece which is held on the crank by four little screws. My local shop and I have tried everything and nothing will stop this from squeaking. Could my bottom bracket not be faced properly or is it the crank?
This is not an exceptionally durable or well thought out design (typical Cannondale), and those little bolts have to be torqued frequently; they are easy to overtighten, and will develop creaks and eventual fatigue if they are not torqued at the specific intervals specified in your owner's manual. It is possible that your bb is not tight enough, or that your crank is deformed at the taper, due to riding with loose crank bolts. With this crank, I would assume that it is the taper, or fatigue at the chainring/crankarm junction, and either case involves crank replacement.
I have a Ross 21-speed mountain bike that has a hopeless rear rim that I need to replace. I want to buy a new rim, but will I have to change everything like the freewheel, the crank, the chain, and the pedals. I have no problem in doing so but just want to make sure. I just brought two new wheels for it.
Thanks a lot,
You, like many other people, suffer a semantics syndrome, whereby the word "rim" is frequently substituted for the word "wheel", and the two items are very far from one and the same. If you were, in fact, replacing a rim, then the only compatibility issue would be spokes, which should be replaced on anything over a couple of years old anyway. Since the rims that you think you need are probably wheels, then, really the only issue is, if the old Ross has a freewheel, the the rear hub must be threaded to accept a freewheel. OR, the drivetrain must be Shimano compatible in order to use a cassette hub to its best use. If you replace the freewheel with a cassette, then you should at least replace the chain; otherwise, it should work ok.
I've got two bicycles and they both have two flat tires. I've never changed flat tires on bicycles before and I want to know if it is very difficult. I also need to know how do I know what size tire to buy. I do not know what they are. Is there some kind of way I can measure the wheel and I will know?
Also, one of my bikes is a touring bike and it needs new tires also. What should I look for in new tires? I don't plan on any off road riding, but I want something that is dependable.
There are a few basic rules in tyre changes--put the rear der in highest gear, use actual tyre tools to remove the tire, inflate new tube till it holds its shape, and don't use tools to install new tyre, unless you're using a speed lever or quickstick. The size of the tyre is always on the tyre somewhere, either embossed or screened on. If you try to measure anything, you may come close on the diameter, but you'll certainly have to guess on the width, so if you can't read the size, take the wheel to a shop to match it with the closest size. Conti, Panaracer, Michelin, and Kenda make decent tyres in all sizes.
I have a 1998 Specialized FSR Extreme (I think it's a '98). Anyway, I love the bike but I'm always having to grease the swing arm pivot. If I don't it makes a horrible noise. I am using "slick honey" grease, recommended by shop.
I hear there is a bearing available to replace the nylon bushings. Do you have any ideas?
To grease it I have to pull the cranks (at least I think, is there a way around that?).
Supergo isn't much help.
Thanks a lot,
I'm relatively ignorant about FSRs, but most bikes that don't have bearings have a permanently-lubricated or self-lubricating bushing, and it should never have any grease or oil of any sort applied, as this will attract dirt and destroy the Teflon or whatever substance is on there. I'd guess that yours is shot, and you should get a new bushing, and follow the recommended procedures for maintenance. I don't know of any bearing replacement for the bike, but it's possible.
PS: Supergo isn't much help to me, either.
Re: My 1999 Haro EX2--the rear suspension RockShox shock. When I went to clean my bike I noticed that my lizard skin covering the shock was completely soaked with oil. I removed the cover and cleaned up the oil slick but I want to know if or how I refill this shock. The damping qualities seem to be gone and I fear all the oil has leaked out do to the substantial amount of oil on the lizard skin. Bummed out in Illinois...I have put only 200 miles on this bike. I bought it as a closeout for 1999.
If you had bought the bike here, and it was under warranty, I'd replace the shock and send the old one to RS for a rebuild or replacement. These types of problems are beyond the scope of most fixityourselfers, so why bother if it's less than one year old? You can poke around of the RockShox website and maybe find a little more info, but I don't recommend trying to fix it yourself.
I've been having some problems with my chain slipping off the smaller gears on my rear wheel whenever I pedal hard.
The problem started after I had it tuned up, at which time the mechanic replaced my worn chain. I then replaced the rear cassette, which helped a little--it now only happens going uphill.
The mechanic now claims that I have an incompatibility issue with grip shifters and a Shimano STX rear der. This may be true, but I don't see how it is causing my problem.
I would replace the shifters and rear der, but don't want to replace everything else (I have a 7-speed cassette). I was thinking about getting STX rapid fire shifters and an XT rear der that supports 7-speed. Will this work, or do you have any other advice for me?
Thanks for you help,
Do you believe that the designers at SRAM all got together and decided to make their shifting system compatible with all Shimano drivetrains except STX? You need a new mechanic, for one thing. I can't answer your question without having the bike here, but I can tell you that the grip shift should work with any Shimano drive train, and if it doesn't, the problem is probably not in the shifter. If you replace enough parts, it should stop. If you hate grip shift, get the rapid fire. XT for a 7-speed is a bit of overkill, but as long as you don't buy a new 9-speed der, it should work. If your problem is only happening on small gears, I'd look at the cassette even if you just replaced it.
My question's about a specialized future shock, I think a '94 model. How much oil do I put in each side?
If it is a 1992-94 Futureshock, use 35 to 50 lbs, more for heavier rider, and between 33 and 43mm of oil (more air=less oil). This is a rather inexact science, as oil viscosity, height, and the amount of air all influence one another. Check the RockShox web site; I'm not sure if they have information on shocks this old or not. Also, whatever air and oil ratio you agree on, if the fork has not been rebuilt, you'll be adding both air and oil frequently, perhaps hourly.
The Old Steel-Aluminum Question Arises Again (read through all indented emails below)...
I am currently riding a fairly old, but very good steel-frame TREK that I built back in 1982 when I was a mechanic in a bike shop. At that time, I used Campy Record deraileurs and hubs with a 6-speed freewheel (cutting edge for then!). I would like to upgrade to an 8, 9 or 10-speed cassette and brake-lever shifters. I have been out of the cycling world for a while and only last year came back pretty strong. While I know the gearing range I need, I have no knowledge at all about the new hardware. My frame is spaced at 126mm and I know the new hubs are 130mm. Knowing what I do about frame dynamics, I'm willing to take the chance on making the 130 fit into the 126, but what else do I need to be concerned about in order to make this upgrade work? Is going to 10-speed pushing it? Do I need to replace my old Super Record crank as well?
Any information you could provide would be greatly appreciated.
It is easy to spread a steel rear triangle to 130, if you have the right equipment. All 8,9,and 10 speed drivetrains use the same spacing, and you really need to replace everything if you want it to work well. Your crank may work with 8-speed, but I doubt that it is spaced to work well with Ergo or STI. Consider the cost of a new 9-speed gruppo against the cost of a brand new 9-speed bike. Unless you are hopelessly in love with this bike and its wheels, tires, bars, paint, etc. are in perfect shape, I would advise against the upgrade.
I have recently purchased a Bianchi Eros with a 52/42/32 Campy chainring. I have noticed that the Eros 2000 model has changed the 32 to a 30-tooth ring. I am in need of lower gearing since I live in a hilly part of Seattle, WA. If I am willing to keep the rear cluster in the upper half when in the lowest gearing in the front can I go even smaller than 30 teeth on the grannypa gear? Does Campy or anyone else make a less than 30 tooth gear that will fit this 135 mm 74 mm bolt circle? Can I find someway of exchanging my 32-tooth gear (which is virtually new (37 miles total so far) for this lower-tooth gear?
I won't say that there is nothing smaller
than 30 teeth for Campy cranks, but I will say that it'd be tough
to find. If you need to go lower than 30, it would be easier to
use a lower geared cassette. Nobody's going to take your
virtually new chainring on trade, so you'll have to buy all new
parts. Much deviation from the stock Campy set up will cause
grief, so I'd learn to mash a
13-28 exadrive cassette and be happy; otherwise, you'd need a mountain bike crank, and that really wouldn't work on this bike.
I have a Cannondale R-900 with Shimano 600 index shifting. For a while now I have been having a problem shifting down to the smaller cogs on the rear deraileur. It seems that when I try to shift the lever to go down, there is no click, it just moves like there is no connection taking place. but after a while, after many attempts, it will finally catch and the chain will move down. I have no problems moving up the cog, just going down, any ideas?
It sounds like a defective or worn out shift lever, but it could be something like cable friction, or it may be remedied by cleaning and lubing the shifter.
How do I measure my bottom bracket? I cut a couple of road bikes up to make a recumbent. Now I want to put a cassette type set-up in it, but I don't know how to find out what size I need and I live in a small town and the mechanic at the bike store told me that I'd have to pay him for trial and error. I think that means he doesn't know.
It's truly a pity that your local mechanic wouldn't spend hours sticking parts on your rig to see if it worked for free. What's the world coming to? If you are cutting and welding bikes, probably your only hope is trial and error. BB's have basically 3 dimensions, the shell width (68, 70, or 73mm--this is easy to measure, it is the width of your shell), the spindle length, which is normally dependent upon your selection of crankset, and the threading (68, 73 are English, 70 is Italian). If I told you to buy a 110mm bb for an XT crank, that would work only for a normal chain line (around 50mm), and if your contraption does not have a normal chain line, then you can't know what size spindle will work best.
Can I use 8-speed Campy Ergo shifters on my 8-speed cassette with Shimano spacing?
If you want to, you can use 10-speed record levers with 1990 Croce d'une 7-speed, but if you want it to work well, I wouldn't advise it. You can buy a conversion kit to change Shimano to Campy 8-speed, assuming that the rest of your stuff is Campy.
My first time in the Internet asking advice. Briefly, I have a K2 RS 4000 frame that I built up on. I am a beginner mechanic (yet a perfectionist). I set up the bike with what I thought would be the best parts and flawless shifting. The drive train consists of mostly new 8-speed parts such as: a 1998 XTR crank set w/ rings, 11-30 ti cog set (also have spare 8-speed 12-28 cog sets to experiment with later), IG 90 Chain, 1999 GripShift 9.0 SL, 8/9-speed compatible rear deraileur, half pipe shifter on the drive side that I had cut down to a quarter pipe for no missed shifts.
Just to make sure I purchased two BB's: 1998 112.5 x 73 XTR and the new XTR 2000 116x73 BB with the sealed cartridge bearings. The 112.5 BB was too small. I was told that after I brought it in to the shop because when I shifted in to the second chaining it would hit the frame or jam even on my work stand. Now I have the 2000 XTR 116 BB installed through a good mechanic, but it still protrudes outward quite a bit on the drive side. I am still breaking the bike in.
Is there anything I can do to get the drive side crank closer to the BB and frame? It not only looks sloppy, but I am afraid that dirt & water will work its way in to that space. I know the shop used whatever spacers they could that were included. So, what's the deal? Why would Shimano make only two sizes for a high end BB if it doesn't fit perfectly? Please email me with an answer.
Sammy AKA Samantha
Don't ask me why Shimano does anything--they do what they want when they want and you can't do anything about it except not buy their parts, which is my first suggestion in this case. I assume that this is some sort of full sus downhill type freeride rig, and it probably has some sort of screwy bb shell or pivot--really, I don't know everything, especially about k2 or schwinn, or most funky full sus designs in general. You've already spent too much, so springing for a square tapered crank and a bb with an adjustable chainline is only reasonable. Your only other alternative is to use the XTR with too big a Q factor, or possible space out the shorter bb with freewheel spacers. Shimano is not letting anyone else manufacture a splines bb, so that's what you get.
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