I am pretty sure 7 speed wasnt common in the 70's (somebody correct me if I am wrong)
I think 7 or 8 speed uses a thinner chain than 5 or 6 speed.
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I am pretty sure 7 speed wasnt common in the 70's (somebody correct me if I am wrong)
I think 7 or 8 speed uses a thinner chain than 5 or 6 speed.