invert spring question

[chuk85]

I read all kinds of things about "cutting down" full size forks to length for the 250r (what im planning on doing) but what do you do about the springs?
do you just leave them longer and cram them in?

Cutting them down would screw up the spring rate im sure...right?

I suppose you could use 250r springs? or maybe ktm 85 springs?

any input would be great to know because this has been bugin me for awhile now

[Red Rider]

I read all kinds of things about "cutting down" full size forks to length for the 250r (what im planning on doing) but what do you do about the springs?I don't know what others, that shortened their forks, have done for springs, but I'll share what I know. If a suspension co. is doing the shortening for you, they'll handle the springs as well. If you're doing it on your own, then you'll want some shorter springs.


do you just leave them longer and cram them in?Probably not, they most likely had some custom length springs made. Depending on how much you shorten the forks, trying to "cram" the "full-length" springs in could prove to be impossible.


Cutting them down would screw up the spring rate im sure...right?Yes, cutting them down will increase the spring rate, which could be good or bad. It all depends on what rate you're looking for.


I suppose you could use 250r springs? or maybe ktm 85 springs?Probably not KTM85 springs, as they're already too light for what you'll probably need, unless of course you go to a custom spring. If you do that, you might as well go to a custom spring designed for the shortened forks you're using.

[chuk85]

awsome, thanx for the info

[barnett468]

Hello

It doesn’t matter what the spring rate is right now because you don’t know the spring rate of either fork so you simply should cut them down by the same length or 1” less than you cut your tubes down by and try them. If they don’t work try stockers if you have them or just order new ones.

They make springs so if it’s soft just get a slightly higher rate. Preload is typically between 1”-1 1/2”.

For every 10% you reduce the length of a linear rate spring you increase it’s spring rate in lbs per in by 20%.

In other words if your springs are 20 lbs per in and 32” long with 1” preload and 12” travel you have a compressed rate of 1” preload = 20 lbs per in + 12’ travel x 20 lbs per in = 260 lbs per in compressed.

Cut your tubes 4” inches and then shorten your springs 4” you now have increased your spring rate by 25% = 5 lbs = new spring rate of 25 lbs per in. Take 1” preload = 25 lbs per in + 8” current new travel x 25 lbs per in = 225 lbs per in. compressed.

As you can see the compressed rate is 35 lbs x 2 for 2 forks = 70 lbs less total than the original setting when fully compressed. There is no way to tell how this will work unless you either try it or know what your factory spring rate is etc.

250R springs might work don't know.


Hope this info helps.