changing cassettes, chains & cranks

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6 replies [Last post]
Anonymous's picture

My 5 year old Cannondale is due for an overhaul. I believe my bike came with a Shimano RSX 7 speed 12-25 cassette.(?) My shop told me they will put in a 13-21 cassette. (huh?) What's the diff? If I am having the chain and cassette replaced, does it also make sense to replace the crank? After all, why wouldn't they all wear out at the same time? Oh no, I've just exposed myself as clueless about bicycle mechanics before all my cycle-wonk, gear-head friends!!!!!!!!

Anonymous's picture
Evan Marks (not verified)
7-speed cassettes

One catalog I just looked in listed 11-28, 12-21, 12-28, 13-23, 13-26, and 13-30. Tell the shop to try a little harder.

Chainrings should last at least 10,000 miles and possibly as much as 40 - 50,000 miles, far longer than a chain or cassette. Ratty-looking chainring teeth can still function well as long as the chain isn't getting stuck - a chainring engages the chain under tension, pulling the chain into the teeth, while a cassette cog *releases* the chain under tension, allowing it to skip if the teeth are worn. That's an oversimplification - there's more to it but that's the general idea.

Anonymous's picture
richard rosenthal (not verified)
Name the shop that put on that 13-21 so we know to avoid them.

David, this city is full of places that fleece uninformed cyclists and take huge advantage of them.

I've never hesitated to name names and report the stories to other cyclists. Only in this way, and in consumer-resistance can we bring these predators to heel.

So what store was it that replaced your 25 with a 21?


Anonymous's picture
Dave Sabbarese (not verified)

Evan, Rich, thanks for the input. The shop put the cassette on this morning. I've had a good relationship w/ them over 5 years, but I should know more about this stuff. I'll try it out this weekend, I bet I won 't even be able to tell the difference. If I do find it uncomfy, I'll ask him to change it. But it's not like I'm gonna report the guy to the Better Buz Bureau. Evan, Rich thanks, again.

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