Mountain Bike Reviews Forum banner
1 - 6 of 6 Posts

·
Arnold
Joined
·
44 Posts
Discussion Starter · #1 ·
What's the difference between a fork that is suitable for jumping and one that is not? Is it all in the stiffness/rebound? For example, a
"non-jumping" fork (XC) with air springs and adjustable rebound - can it be setup for a more aggressive use, and perform similar to a fork that is meant to handle jumps/drops (we'll take the travel out of the equation for ease of comparison)? Am I understanding correctly or am I way off?
 

·
trail addict
Joined
·
1,866 Posts
Arnold said:
What's the difference between a fork that is suitable for jumping and one that is not?
Differences-one is suitable for jumping and the other isn't.

OK, sorry, that is the sarcastic answer.

XC fork-lightweight, designed to take "normal" trail stuff like roots and rocks, probably QR, and also usually factors in climbing efficiency

"Jumping" fork-heavier, made to take some abuse, not necessarily stiffer (stiffness depends on rider weight) but damped differently-probably more compression damping-not good for soaking up small trail chatter, not necessarily longer travel (Marz DJ and RS Argyle are 130ish?) because dirt jumps are normally groomed a little, probably 20 mm axle for strength.

If you want a "jumping" fork for Downhill or Freeride use, then that is a little different...

Air spring and adjustable rebound alone won't really do what you need to make a XC fork into a "jumping" fork. And unless you are really light, you are gonna beat the heck out of a normal XC fork (and frame) by taking flat or rough landings. Small to medium sized jumps and drops with nice transitions are OK.

If you are really serious about jumping, get a frame and fork made for it-it'll be worth it in the long run for sooo many reasons.
 

·
Arnold
Joined
·
44 Posts
Discussion Starter · #3 ·
Uncle Six Pack said:
"Jumping" fork-heavier, made to take some abuse, not necessarily stiffer (stiffness depends on rider weight) but damped differently-probably more compression damping-not good for soaking up small trail chatter, not necessarily longer travel (Marz DJ and RS Argyle are 130ish?) because dirt jumps are normally groomed a little, probably 20 mm axle for strength.
Is the compression dampening controlled by the air pressure in the air spring? Or is it something that is controlled by the weight of the oil? I'm confused here as they seem to do the same thing to me.
 

·
moaaar shimz
Joined
·
9,125 Posts
Air pressure controls preload and in air sprung forks it also controls spring rate. Compression is controlled by a regulating valve in the piston (if it closes a bit the compression damping increases as there is lower oil flow, if the hole opens it decreases compression damping as there is higher oil flow).

Rebound is controlled also by a regulating valve in the piston which controls the speed in which the oil flows back after the piston is compressed.
 

·
trail addict
Joined
·
1,866 Posts
Arnold said:
Is the compression dampening controlled by the air pressure in the air spring? Or is it something that is controlled by the weight of the oil? I'm confused here as they seem to do the same thing to me.
I don't know a lot about fork internals, but damping is mainly controlled by oil wt and some type of regulating valve. Air pressure is the actual spring-it is what supports your weight.

They sound like they do the same thing, but it really is different.

The spring is set for your weight.

The compression damping is set for your riding style.

Maybe that is a little over-simplified.

The spring + your weight is what makes the fork go up and down. The damping (comp and reb) is what keeps the up and down from being out of control. You could have a ton of pressure (spring rate) and no damping and it would ride like a pogo stick. Ton of damping and no pressure would make a fork that would bottom (slowly) by just sitting on the bike. So air pressure and comp damping are separate, but related parts of fork tuning. They must be somewhat balanced and tuned to what you need to work ideally.
 

·
dontcha?
Joined
·
1,433 Posts
Basically if you wanna use your XC fork as a "jumping" fork, max out the Air spring psi, and increase the compression as far as it'll go and adjust the rebound fairly fast to take up any small bumps.. yeah u could take it apart and change the oil and whatnot, but that's a pain.. see how it feels after doing the above..
 
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top