Originally Posted by HillRider
Actually the most common way to measure the BCD of a 5-bolt crank is to measure between the centers of two adjacent bolts. The bcd in mm is the distance between the bolts multiplied by 1.701. For example, a 5-bolt crank with two adjacent bolts 64.7 mm apart would have a bolt circle of 1.701*64.6 = 110 mm.
Thanks, that's pretty much the exact info that Sheldon linked to on his site and it's helpful stuff (gotta remember to bookmark it this time). I found that on this particular crankset, the large and middle rings are riveted together and the BCD is more in the 70-72mm range connecting to the middle ring. The teeth that I thought were badly worn appear to be of the 'shift assist' nature. There are about 4 stubbies right behind the crank arm and 4 more 180 degrees around the ring. I didn't really notice the ones behind the crank arm before and thought the select teeth were damaged. I guess I'll just clean it up a bit and replace the chain and cassette (already did the tires). Should be a decent bike to tool around on.
Thanks again to Sheldon and others here!
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'14 carbon Synapse - '12 CAAD 10 5 - '99 Gary Fisher Big Sur