Bicycle Mechanics - Question aboutcompatability: Replacing a 24/34/42 crank with a 22/32/42

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Raleigh71
01-01-10, 09:00 PM
My crank is kaput, with a bunch of broken teeth on the largest chainring.

It's a single-piece 3 chainring Shimano assembly with 24/34/42 teeth, mated with a 7 speed freehub.

I can replace it, but all the replacements are 22/32/42.

Won't the indexed shifting get screwed up if I change the number of teeth?

bikinfool
01-01-10, 10:30 PM
Maybe you'd have to adjust the low limit screw on the front derailleur but I'd try without first. Shouldn't be a problem, not a big difference. However, if you replace the crank itself you may end up with a different chainline, which would mean further adjustment to the front derailleur. Your shifters won't notice the difference (where the indexing is). Worst thing about changing number of teeth might be chain length if you dropped teeth of your big ring (like removing it) where you could shorten your chain...
oldbobcat
01-01-10, 10:32 PM
Won't the indexed shifting get screwed up if I change the number of teeth?

No. It will get screwed up only if you change the spacing between the chainrings.