140mm travel fork too tall for dirt jumping?


I really dig your website and all the solid advice and especially all the good pump track action.

I recently built up a new dirt jumping bike with an azonic steel head frame which has classic dirt jumping geometry. I got a great deal on a new fox vanilla rlc 32 fork.

This bike rides great on trails and really soaks up bigger drops. I haven’t gotten a chance to jump it yet since there is still lots of snow around as Flagstaff Arizona is at 7000ft. Is such a tall fork going to be a problem dirt jumping?


Jay Holt
Flagstaff, Arizona

Hey Jay,

140 millimeters are about 40 millimeters more than that bike is designed for. Compared to stock, your bike is much slacker, and it’s bottom bracket is much higher. I can see how that might feel good on trail and off hucks.

As far as dirt jumping goes, there are two concerns:

1. Too-high bars. With that fork on that bike, you should run a low stem and bars.

2. Excessive squishiness. The plushness you love on trails will make your fork collapse under the heavy Gs of dirt jumping. Your bike will jump better if you tune the fork to resist the pump.

Your FOX VANILLA RLC 32 is very tunable. Here are a few options:

– Max your low speed compression. That’s the ring on top of your right fork leg. That will make your bike feel a bit less plush but more stable.

– Try a stiffer spring. That will give you more control and pop — you’d be amazed at how heavily you load your bike when you dirt jump.

– Jump with the fork locked out. The knob on the bottom of the right leg adjusts the lockout threshold, so the fork can be moderately responsive or fully stiff. I know people who jump locked out, but I like my fork to feel the same all the time.

Good luck, and have fun!

— Lee

Related: Bad idea: Long travel fork on trail hardtail

6 replies
  1. leelikesbikes says:

    Hey yeah, I remember shortening my old Vanilla from 5″ to 4″. It made my old Tazer handle a lot better.

  2. jay says:

    Well ive done some checking into lowering my fork. There is no offical fox way to do it. PUSH tuning service says it cant be lowered. There are no spacers on the stock spring stack or negative spring on my fork. I am pretty sure it uses the same dampener as the float rlc and maybe the talas as well. This is good news because the float can be lowered to 100mm from its stock 140 by adding 2 20mm spacers to the negative spring. It would seem I can just get a vanilla 130 spring of the correct length, put some spacers on the negative spring and the spring stack since the 130 spring is shorter. For the 07-08 140 vanilla there are 4 different spring weights availabe. For the 06 vanilla 130 there are 6 spring weights available. I guess now I just need to know the length of a vanilla 130 spring. Can some one with a spare 130 spring laying around answer this ?
    I wonder what is up with fox saying this fork cant be lowered? are they just getting lazy and dont want to produce more springs or what.
    Also if I were to cut one of my 140 springs would the spring rate go up or down and by how much? I seem to recall a previous post about how spring length effects spring rate.

  3. Zen Turtle says:

    I just bought an Azonic Steelhead XL Pro to build my first dirt jumper bike. I haven’t picked a forks yet but I was looking at a MArzocchi Dirt Jump 2 with 100mm of travel.
    I agree 140mm may be too squishy, but why do you mention “Too-High bar” as a problem?

  4. leelikesbikes says:

    Too-high bars limit your sprint power and adversely affect your handling.

    Many, many riders have their bars too high on DJ/FR bikes.

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