Suspension tips from Fitz
So last summer I lived up in Whistler and if there’s one thing I did a lot, it was hit berms filled with teeth-chattering holes and braking bumps. I ran a DHX 5 on a VP free with the propedal at its lightest setting and the bottom-out resistance at its firmest setting. I felt that max bump complicance + sturdy bottom out worked well, but i didn’t really try any other settings. Reading the recent piece on propedal (FOX PropPedal and suspension bracketing) got me thinking that perhaps this set up is bad for bumpy berms: perhaps the lack of propedal was allowing my suspension to blow through the first half of travel in response to the G forces in the berm and forcing it into the heavily damped end-of stroke.
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the holes and bumps in a fast berm are essentially the kind of high-force, high speed impact that bottom-out resistance is going to counter, right? in this case, might mimimum propedal make the suspension feel harsh? might a better set-up use more propedal to keep the mid-stroke available for bump absorption, even though additional chatter might come through? i think this question is relevant for downhillers, park riders, and anyone else who wants to get their shiz dialed. thanks for running a great site: more substance, less advertising: a winning combo!
Awesome question. I sent it to my man Mark Fitzsimmons (“Fitz”) at FOX Racing Shox.
Fitz likes bikes. Fitz knows bikes. Fitz rips on bikes. Crabapple Hits at Whistler.
This is a really good question Calen has.
There are a couple of things Calen could do if this situation rises again.
1. Make sure the front and back are balanced well. In fast bumpy berms such as A-line, weight bias and suspension balance play an important roll. If the front is riding high (which could be from handlebar/stem/suspension setup), the weight will be on the back of the bike loading the suspension. So again, properly balanced springrate needs to be know first. Measuring sag will determine this.
2. Experiment with rebound. A common misunderstanding in the suspension world is I need my bike to feel glued to the ground or not buck me so I will slow down my rebound. When in fact this will often make the situation worse.
3. Compression (propedal). The combination of the VP free’s linkage design and the DHX coil allow for a bike that pedals really well, and goes through root/rock sections absorbing anything in it’s path. The side effect of these great traits are that in certain situations, the bike will ride deep in the stroke during g-out situations. Adding ProPedal (low speed compression) will help reduce this. Also going up in reservoir pressure. Often pressure is set to low and the adjustments will not provide adequate range. First set the IFP pressure to 175 – 200psi and than experiment with the ProPedal adjuster and Bottom out adjustment.
4. Tires. They work in sync with the suspension more than you realize. Often times chatter that transmits through the bike and into the rider is due to tires. Pressure, compound, etc.
5. Perhaps for Calen’s riding style and trail preference, he might need more compression on the main piston. This is done through revalving. A local tuner should be able to help with this.
Keep in mind there is no perfect set-up for every condition. Whistler is one of the most difficult to digest. The set-up that works best for terrain at the top of the mountain when it is wet, will not as good on A-Line. In the end choose how you want the bike to work best for you in the conditions you ride in most and tune it for that.
And never forget, suspension will not make up for a rider who has gone down A-line 8 times in a day and is tired. Upper body fitness is important.
Great response to a great question Fitz.. That pretty much sums up any question about suspension.
I was under the impression that the DHX 5’s pro-pedal adjustment only effects the first quarter or so of the stroke of the shock. If this is the case then you’d already have blown through the part of the travel that the propedal adjusts by the time you get up to the bumps in the berm.
then again, i’m probibly worng.
dang! thanks mark and lee! this is like christmas for bike nerds! i think that this site is one of the only places on the net where this kind of discourse is available to riders. so rock on! i hear you on the fitness thing. 8 runs? how about 15? funny how all the little bumps seem to get bigger as the day goes on. but i’ve got 2 words for them: James Wilson. calen
If I’m not mistaken, I think the Pro-pedal feature is the same idea and the SPV system in Manitou air shocks. Basically it’s not the distance along the stroke that is in question but the speed.. where the shock just acts differently to force applied slowly (rocking motion from pedaling) as opposed to quickly (bumps, etc.) Of course if you have much “bottoming” resistance then the first half of your stroke will be more susceptible to pressure and this combined with too high of a return damping setting will definately keep you near the bottom of the stroke, where the Pro-pedal won’t be of much use. I dont know if I’m making sense but I hope this helps.