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Old 09-13-2009, 07:53 AM   #22
mtothef
Gnarly Adventurer
 
Joined: Dec 2006
Location: santa cruz, ca...
Oddometer: 361
cool project!

Quote:
Originally Posted by Byrdman
The next step is to start chopping my spare 919 frame apart. I'm going to "move" the stock swingarm pivot down about 1" and back about 4". That will align the swingarm and chain angles.
careful with the swingarm pivot relocation - the further the pivot is from the countershaft sprocket, the greater chain tension differential you'll have as the rear wheel moves through its arc. basically super slack at top out, to super tight at the point where the countershaft, pivot and rear axle are all in a line, then looser again at bottom out. the more travel you have, the bigger an issue this becomes. that's part of the reason why newish mx bikes have their countershaft sprockets almost touching the swingarm pivots, and why old-ish long travel mx bikes have all kinds of chain tensioners and old timers have all kinds of "that time my chain went through my engine case..." horror stories. otherwise, kickass!
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