bike repair/maintenance

Question
QUESTION: Hi-
I brought my Giant Yukon SE mountain bike to a bicycle shop this past weekend for a tune-up.  It had not been professionally serviced in quite a while, so I thought it would be a good idea.  The bike will be 10 years old in a few months; I'm not sure how many miles I've ridden it during that time.  The guy at the bike shop used some sort of tool to measure the slack in the chain, and said I should replace it.  Isn't it possible to just remove a link or two from the chain, rather than have to replace the entire chain?  Also, he said that once he replaces the chain, the cassette may need to be replaced as well.  Is that true, or is he just trying to build up the bill?
Thanks for your help.

ANSWER: Mark,
This may not be the answer you want to hear, but, yes, if you leave a chain on for a very long time, it stretches and wears the gear spacing between the teeth in the cassette to match the stretched chain roller spacing.  Then, when you put a new, tighter chain on the old teeth, it either shifts poorly (because the links aren't going neatly into the spaces between the teeth) or the wider gear teeth spacing encourages the new chain to stretch sooner than it should, thereby wearing it out ahead of schedule.  I have found that if I am good about replacing the chain nice and early, I can keep a cassette for two or, if I clean the chain regularly, three, chains.  If I let a chain go too long, forget it: New chain and cassette.

So, knowing that you should replace both at the same time in this case, what you are probably interested in is keeping the expense down.  The best way to do this is go to the shop knowing the prices in advance through internet research.  There are a ton of mail order places, such as Colorado Cyclist, Tree Fort Bikes, Cambria Cycles, Price Point, etc., that discount cassettes.  Depending on the model and year of cassette, you can get a good one for as little as $30 and a decent chain for $20.  Knowing this, you can better evaluate whether you are getting a good deal at the local bicycle shop.  If you are nice about it, they may even match the prices for the parts.  You likely have Shimano components, so you probably should look for a Deore XT or LX 9-speed cassette 12-27 or 12-32 (if you ride hills a lot) and a SRAM 9-speed chain.

One other revelation is that replacing a chain and cassette is neither hard nor expensive, just dirty.  A chain breaker, chain whip and lockring tool are not very much and you can reuse them over and over.  Just something to think about, because doing it yourself prepares you to handle a future on-road chain problem and make chain replacement cheap.

Let me know if you have additional questions.

Graeme



---------- FOLLOW-UP ----------

QUESTION: How often do you recommend replacing the chain in general?

Answer
Mark,

It depends greatly on the amount of hard riding and dirt that gets in the chain.  If you are riding tough mountain bike trails, changing gears frequently, getting it muddy or wet and cleaning the chain every two or three rides, then something like 700 miles and you should replace the chain.  If you are mostly on easy, smooth dirt roads or bike paths with little dirt or rain, you can go 1000 miles or more.  

It also depends greatly on your maintenance.  Cleaning lightly after every ride and thoroughly after every 4-5 rides will lengthen the lifespan of both the gears and the chain (as well as the derailleurs).  Letting it go for two years without care, well, that will guarantee the need for a full replacement.

Another good way to tell is if the chain isn't shifting crisply when you click the shifter.  If it hesitates and then shifts, your chain may be ready for replacement.  Lastly, think about getting the chain stretch tool the shop used on your chain.  The tool from Park Tools really isn't terribly expensive or high tech and can tell more accurately than most anything else.

Happy to answer other questions if you like.

Graeme