Re: [St] Aluminum or Steel...SHORTEN THE WHEELBASE? YOU SMOKIN' CRACK?

[JES_VFR <jes_vfr@xxxxxxxxxxx>]

At 08:54 AM 12/21/2008, you wrote:
> Matt,
>
> When I did this to my Superhawk it was an accident ( I cut the chain 
> to the stock length before I realized I was adding three teeth to 
> the program). I inquired with a few local buddies with more 
> experience than myself, and was told if it fits, it's OK, and will 
> shorten the wheelbase, but exactly as you said " we are not good 
> enough riders to notice" the difference. Well, riding ability or 
> lack thereof not with standing, the difference on my Superhawk was 
> close to an inch, and very perceptible. So in an effort to make the 
> RS more flickable, I thought I would do the same thing...
>
> John

Yeah, 118 links (or whatever your stock length chain is), is a fixed 
length until it is worn. Now bikes have enough adjustment that you 
can move the rear axle enough to resolve the changes in length that 
changing sprocket teeth counts will create. Some won't, since their 
adjusters don't allow that much movement. My RC51 had the rear axle 
just about hanging off the bike, I assumed the PO had screwed around 
with the sprockets and not properly calculated the chain length. It 
did not really matter to me at time since Romeo-Charlie-Five-One was 
plenty rough, and needed quite a bit more than just a chain and sprocket set.
But when I got into it, I found the chain setup was down right scary.
First the front sprocket was down two teeth (it was also not the 
correct sprocket for the RC, with washers acting as spacers to keep 
it aligned with the rear!), and the rear was up two teeth. That got 
me looking at the chain that was on the bike, here the PO had added 
four links. I don't know how he rode it.
I put it back to stock gearing and ended up having to flip the 
adjuster blocks to allow the axle to move forward enough to have 
proper tension.  Now the bike was handling much, much, better.
Okay it is still handling like sh!t, but the problem is now the bike 
can turn and does so very well until the mismatched, wrong size and 
just plain junk tires start to slide. I know that the bike can be 
sorted with some good rubber on it (Hear That Santa!!!) and made to 
handle like it really can.

I started thinking a lot about how little the customers at the parts 
counter know about chains and how they should count teeth.

There are a few simple rules:
1. Anytime you go up or down more than a tooth, you should plan on 
using a non stock chain length. However only take out/add in an even 
number of links. In other words if you went up three in the rear only 
add two links to the count on the chain. If you went down four in the 
rear then take out four links. Again, one up or down on either end of 
the bike is not going to be that critical.
2. Don't assume that the bike is stock at both ends, especially if 
you are going to change the sprockets to something other than stock 
counts. I had a customer bought his bike new at another local shop, 
and had them "hop it up" before he took delivery (it had a TBR pipe, 
pc III, zg double bubble and a couple more bits). He wanted to go 
down Three in the rear so that it would wheelie at the drop of a hat 
and be ready to stunt. Only when we actually looked at his bike did 
we discover that some genius at the other dealer had already gone up 
two teeth in the rear.
3. just like a slightly dropping the triple tree down the fork tubes 
will make a big difference with the way the bike handles, so will 
moving the rear axle fore or aft in the swing arm (not to mention the 
up and down with an eccentric adjuster.



JohnS
A Dragon Ascending
"Forging my body in the Fires of my Will"

_______________________________________________
Triumph Sprint ST/RS mailing list
Send list posts to ST@xxxxxxxxxxxxxx
Change your list options at www.Triumphnet.com