PVC pipe inside forks

[Soul]

So, I looked a little on the list but it seems easier and more fun to ask here, what is the main reason for putting spacers inside your forks? My old ones had about 2.5" or so of PVC in them, and they wernt the exact same length either, they are off by 1/8th of an inch or so.. I just got Kennie's forks and I was wondering if I should put the pvc in those, or use a thicker fork oil, or if i should just leave it alone.
suggestions, ideas, comments?

[rclinc2]

the spacers allow you to have some control over the preload setting, longer spacer=more preload. an easier way to get the sag adjusted would be a set of adjustable preload fork caps (from an F2 works) with the spacers cut to the length where they touch the installed caps with the caps set to minimum pre-load. The fork oil is going to effect the damping of the fork, either more or less damping depending on oil weight, but will not do anything to getting the sag adjusted, which is where you want to start. a really usefull suspension guide was published in roadracing world a few years ago in a series of articles by Max Mcallister from Traxxion Dynamics titled 'the clubracers guide', it might be available online in back issues of that magazine?

[dagus]

remind me to send you an article I have from about 1990 or so, addressing this whole issue. Don't go with PVC. Get stiffer-than-stock progressively wound springs and add heavier oil.

The reason for the PVC is to stiffen up the suspension; if you do it, go with heavier oil too. But progressively wound springs stiffen up as pressure increases - much smoother.

Talk to Steve Lenac. I'm going to have him upgrade my own fork springs soon!

[Soul]

What weight of oil is recommended in the shop book?(I have it but I am not at home at the moment and I am curious)
And most importantly, what weight do you recommend??
Thanks for the answers guys. I love the forums!

[rclinc2]

i tried progressive springs , but wound up going with eihnbach straight rate springs set for my weight at the time that the internals were upgraded, (was reccomended by the gentleman doing the forks) so i couldn't say that they were any better than the progressives as so much else had been modified at the same time. i think (it's been awhile) i last changed the fork oil with 15W, which was pretty firm.

[Stevenjhow]

I have really soft forks and I believe they are totaly stock. What is the easiest thing to do to make them better (taking money into consideration). I have read of putting progressive springs, emulators, and stuff like that, but how much does that stuff cost and where can I get it (who makes them)? Thanks

[ponley]

For what it is worth the progressive rate spring is designed to give a plush wallowy ride over most bumps and stiffen up when you need it. It is a compromise at best, ask yourself what you want before deciding on your spring. If you want to be able to setup a really sporty canyon carver then go with a straight rate spring, if you want something that is somewhat sporty and comfortable for long touring then the progressive is for you. The problem with the progressive is when you really start tossing the bike into the corners you have to wait for the progressive (tightly wound, soft part of the spring) to bottom before the stiffer part of the spring will take a set. This means that you must turn in slower so that the bike doesn't overshoot and give you a bobbing effect before taking a set. The downside to the straight rate spring is that it will let/make you feel every little bump in the road. Also avoid the temptation to increase stiffness with oil weight, you want to ride on the spring and use as little damping as possible to control the spring. If you have too light a spring for your weight and increase damping to compensate, the damping will try to throw you off when you hit a big bump. The spring will exert the same force no matter how fast you try to compress it, the damper will exert exponentially higher forces as compression speed increases (cartridge mods will try to reduce this effect).