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Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!ihnp4!qantel!hplabs!oliveb!olivee!spud
From: spud@olivee.UUCP (John Purser)
Newsgroups: net.cycle
Subject: Re: front suspension
Message-ID: <436@olivee.UUCP>
Date: Tue, 5-Nov-85 20:46:19 EST
Article-I.D.: olivee.436
Posted: Tue Nov  5 20:46:19 1985
Date-Received: Sun, 10-Nov-85 09:29:20 EST
References: <135@bridge2.UUCP>
Distribution: net
Organization: Olivetti ATC; Cupertino, Ca
Lines: 41


> 
> Recently an amateur racer, who also rides an '84 FJ600, 
> suggested I forget the air-caps and install progressive springs 
> in the forks and bump up the fork oil from 10w to 15w. He claims 
> that tuning with air-caps is impossible since the air expands and 
> contracts due to temperature. Also, air tends to leak somewhat. 
> 
> My question is: Is he correct?  Why then do most sport bikes 
> now come with air-caps? For hard, fast riding, which is more 
> likely to improve handling, the air-caps or progrssive springs?
> Would some combination of the two be even better?
> 

I've never used air caps, but I do have progressive springs in the
forks of my 650 Seca. My reason for going with progressive springs
rather than air caps was that I didn't want to use air preasure
in forks that didn't have fork seals that were designed for the air
preasure. I understand that seals not designed for the preasure may
bind on the forks when under preasure or start leaking.

I'm quite happy with the progressive rate springs. They allow me to
get on the brakes deep in the corners without anxiety, I've never
bottomed them out yet and I still get a reasonably complient ride.

I think the reason the factories go with air caps is that its more
adjustable for the range of riders that will be buying the bikes, and
its cheaper. With my progressive rate springs I spent an afternoon
of placing spacers in the forks to preload the springs then racing
up a near by twisty bumpy road to see how it worked then adding more or
less preload and trying it again. This was a minor pain in the butt since
each time through the cycle I had to take off the handle bars, loosen
the top triple clamp, then take off the fork caps, put in different
spacers, put it back together and try it again. The results have been more
than worth the effort except that it's made the limitations of the rear
shocks very obvious.

Motorcyclist magazine had an article in the January !985 issue on
front fork setup. They suggested starting with progressive rate springs
then using air preasure and fork oil weight and quanity to fine tune
the suspension. If you can find the article it would be  big help to you.