I have 2007 pike 454 coil u turns. If i start a descent at 140mm they are sometimes down to nearly 95 – 100mm after just a few minutes.

anyone else experience this and can shed any light on any solutions?

presumably it is physically winding itself down so you have to physically wind them back up again. I can’t see how else that happens.

Since there will be a tiny amount of play engineered into the spring helix (just so it can be turned by hand) then then the spring would wind itself back down the helix (which in u-turn forks is fixed: the whole spring rotates with the u-turn knob) on long bumpy descents if there is nothing else to oppose that rotaion, of if there is too much play between the spring and the helix.

So:

I would first check underneath the u-turn knob: have a look at the excellent guides from tftuned or sram on what it should look like if heralthy and how to do it all back up: you need to see if you have three springs with three little ball bearings on them (and one or two might not be enough to oppose any rotation of the spring), also check the condition of the underside of the knob itself which should have several individual circular indentations which make the ‘clicks’ as you turn the knob. If these indentations are knackered ie worn into each other it may be that as the spring compresses and extends, the lack of springs/ball bearings or lack of ‘clicks’ allows the knob and therefore the whole spring to rotate and creep downwards. At which point i would have thought you needed a new u-turn knob.

If it is all clean and ‘crisp’ then grease the srings, balls and underside of the u-turn knob and do it all back up (there is a torque setting somewhere iirc) then have another go downhill. If it still winds down, it may be that the helix is worn to the point that the spring moves up and down it too easily (and overcomes the spring/ball bits in the u-turn knob): you would then need a whole new spring (which comes with the helix and rod to the bottom of the lower leg and the top cap).

Hope that helps!

cheers for that, i was sure i’d read something along those lines a while back. I’l have a gander, much appreciated 🙂

umm, too much rebound damping causing the fork to pack down during repeated hits?
do you get the travel back by winding the u-turn out? if not then unlikely to be the u-turn winding itself in, which TBH i find a bit unlikely, but happy to be shown wrong.

errrm ,yes that too! Easy way to screen for this will be that when it drops down at the bottom of a downhill, yiou either have to wind the fork back out, or it comes back up reeeeeeaaaalllly sloooowly. If you get to the bottom and then turn the rebound knob off and the fork pops back up, then that’s what it was.

if you find need a new medium spring, I have 2, you can have one cheap

yep, have to wind the u turn back out to return to original travel. doubt its too much rebound damping, find them slow enough as it is and run them very fast.

Cheers for the offer of the spring, but i already have one of those as i upgraded to fat bastard x firm.

bloody hell. every day’s a school day.
hope you get it sorted – be interested to know what fixes it.

I think it’s to do with this;

julianwilson – Member
presumably it is physically winding itself down so you have to physically wind them back up again. I can’t see how else that happens.

Since there will be a tiny amount of play engineered into the spring helix (just so it can be turned by hand) then then the spring would wind itself back down the helix (which in u-turn forks is fixed: the whole spring rotates with the u-turn knob) on long bumpy descents if there is nothing else to oppose that rotaion, of if there is too much play between the spring and the helix.

but rather than ‘winding itself down’ that the u-turn assembly is worn to a point that a big hit will cause the spring to push down the assembly rather than actually compress (sort of like when you have a worn thread on a nut and you can ‘push’ it down the threads on a bolt rather than threading it on)…not sure but a possibility??

That would be pretty worn! The plastic threads are quite chunky. How easy is it to turn the U-Turn adjuster? My guess is that it’s rattling down due to an issue with the springs and balls, or worn indentations on the bottom of the adjuster.

Its not dead easy to wind down manually, doesn’t feel any easier than usual really. Have re greased and stretched the 3 little springs very slightly, will see if that helps at all.

Cheers all