[will_5]

I broke my chain today on my 2003 F7. Which chain do I use for a 21 tooth gear on top and a 42 tooth gear on bottom? I have my broken chain, how do I determine what size of a chain it is? Thanks

 

[Quinlan]

There's a general equation that usually works well.

[(Teeth on top gear )+(Teeth on bottom gear)/2]+40 ... round up to the nearest even number.

(21+42)/2=31.5 ; 31.5+40=71.5 ; Therefore a 72 pitch chain should fit about perfect.

I believe those ran a 13wide chain. You should be able to count the links going across the width to be sure.

 

[will_5]

Haha...COOL equation. Yes it was a 72 pitch chain. I just ordered one. Thanks!

 

[cat-sass]

Is there another formula available that would take into account
the extra gear involved in a reverse chaincase?