Topic: shorter swingarm, reduced tire rubbing chance on a lowered bike?

[Matty-Wan]

I think I read once that the cb550 swingarm is directly compatible with cb750 pre-77.  Besides the nice tubular shape, I think this may also have the added advantage of mitigating some rubbing issues on a lowered bike.  If I am correct the shorter swingarm will move the tire more under the center of the rear fender mount.  This will say prevent rubbing that might occur with a tail hoop, aftermarket seat/cowl box, or maybe a license plate yes? Of course the shorter wheel base will raise the bike slightly which works against the lowering objective but it seems like a fair trade off.  Thoughts?

Thanks!

[Retro Rocket]

CB550 arm is longer than the 750's by nearly 2 inches, you wouldn't want to put a shorter swingarm on a 750, especially the K models, Honda went to a longer arm on the later F models to make them more stable {and more trail at the front}, the slightly  longer swingarm is  a common upgrade for the early K models when raced. A shorter swingarm will make the bike less stable and more nervous. As a rule, if you don't understand how suspensions work or what changes to suspensions do then its safer to talk to someone who does or just leave it alone... 

[calj737]

I think I'd evaluate whether my rear shocks were performing properly if you're bottoming out. Either you've lowered your bike too far for the stock shock to rebound properly, or you need a shorter shock with stiffer springs.

It might also be a better solution to change the rim and tire to 1" narrower with a different aspect ratio.

But since you didn't provide any of the details, I'm speculating.

[Matty-Wan]

Well, that is certainly my bad.  I thought I read the the 550 SA was shorter but since it is longer the swap is rather a moot point.  Although the concept is still debatable.  My hunch was a shorter wheel base would make the bike more nimble.  Of course I understand the stock setup is most likely optimal. 

[calj737]

Many bikes with short wheelbases are nimble, but not simply due to wheelbase. Has an awful lot to do with steering geometry, CG, and rake/trail.

I think (and agree with) Retro's point that shortening the 750 wheelbase is actually detrimental to the stability of the bike, hence many opt for a slightly longer swing arm, while maintaining "preferred" geometry measures.

The 550 (especially if braces a bit) is a very inexpensive modifcation that meets this criteria.