[UngaWunga]

Yeah, the title was just to get Branson over here...

What affect does swingarm length have on rear tire traction? For the past year, ever since I put the fast engine in my RD, I've been having some traction issues. Almost been highsided in a few corners, especially up through 4.

I found a nice CalFab swingarm that's a little (maybe 1") longer than the stock one. I know it'll slow down the steering, but it might be worth it if the tire sticks better.

 

[jbranson]

Rob,
Probably won't slow the steering down noticably unless the wheelbase is already very long. Ducs (modern) do pretty well with longish swingarms.

Typically a longer swingarm puts more weight on the front of the bike, however they also help tame the power inputs to the rear wheel. Short of drawing a picture...let's just say it decreases the angle of the chain from the front to the rear sprocket giving the chain less "leverage" on the rear suspension. It helps to keep the engine torque from "winding up" the rear suspension...keeping it more supple during accleration. And of course helps keep the front end down.

There's a ton of geometery involved that I don't understand. But most designers work for the longest swingarm they can get while still keeping the wheelbase within limits. (most of the time achieved by getting the swingarm pivot as close as possible to the drive sprocket...which also has other advantages.)

Off the top of my head I'd think an RD would benefit from a longer swingarm...they steer pretty damn quick. Longer wheel base will add stability too.
JohnnyB