Compression and Rebound

[Oded]

My EX's front suspenion is stock, and work pretty well for slow technical riding. Very soft & forgiving.
Problem arises when I ride faster, the front washes easily from loose rocks and other obstacles.
My worst falls occurred when riding faster on fire roads and single tracks, having the front deflect, and in a blink of an eye, I am on the ground.
Before upgrading the forks and having them tuned, would love some pointers on compression & rebound adjustments.

 

[leeo45]

My somewhat experienced opinion....

With the stock suspension you want to make sure you have sag set correctly and probably want to start in a middle setting on damping and increase the stiffness of both compression and rebound as speed goes up; adjusting only a little at a time as you figure things out. You need to adjust forks and shock. There is a real limit to how well this can work though, especially if you are not the average 70 kilo, intermediate rider.

A steering stabilizer will also help some with the deflecting and crashing, however it will be muting the symptoms rather than fixing the root cause. (pun intended) And I still haven't figured a good way to mount a stabilizer on the ALTA.

I have proven to myself on numerous bikes that having a suspension set up for my weight, size, riding conditions, and speed make a big difference to my level of effort, speed, and frequency of crashing. However, it is still hard or impossible to tune a suspension for all conditions and speeds; e.g. a trials bike suspension will never work well for a high speed desert race. So you need to be honest about your riding and where you want the best results and where you can live with the most compromise.

 

[TCMB371]

Sounds to me like your rebound is too slow. Try backing out the rebound about 6 clicks and see if that helps.

 

[leeo45]

Sounds to me like your rebound is too slow. Try backing out the rebound about 6 clicks and see if that helps.

I had forgotten that the EX has 4CS forks until reading Bryan's comment. They tend to have some nuances when tuning for fast and rocky/rooty offroad riding. (might be true for MX as well but that is not my territory). You didn't say where your clickers are currently set. If you don't know, that would be a good thing to determine and record before doing anything else. At least you will be able to get back to a setting that you like at low speed. And record all the changes you make and your observations.

It has been a few years but I believe the stock setting on 4CS (at least on KTMs) was 15 out on both compression and rebound. Many people think the compression is too harsh on these forks so they back it way out to achieve a somewhat "plush" ride. Not really ideal and if you don't also adjust the rebound that leaves a fork that compresses too easily at higher speeds on bigger impacts and won't return to a neutral position quickly enough to maintain traction. I'm guessing this is the type of situation Bryan is referencing as a likely possibility for your fire road get-offs. BTW, the dynamics are very different at low speed and you won't have the issue riding slow, technical terrain.

One other characteristic of the 4CS forks is that they tend to require a lot of adjustment to feel any change. Most people don't feel a change with only one or two clicks either way.

So the softer rebound is definitely worth a try, especially if you like the way the compression feels. That may get you close enough with the stock forks. If the front feels too mushy with that adjustment then you may need to give up some of the plushness at low riding speeds to improve control at faster speeds. Unfortunately, some of the offroad racers around here never found acceptable settings on the stock 4CS forks (on KTMs).

And make sure your rear sag is reasonably close or you are fighting an off-balance horse. Also something that you won't really notice at low riding speeds.

Let us know your starting point and what you discover.

 

[Oded]

Thanks. That's great help.
I will be sure to record the current settings of the clickers, and start with the rebound.
Sag was calibrated well, and assuming there is no drift in these settings, I'll leave it for now.
These 4cs forks don't get many compline

 

[Philip]

Tuning the 4CS forks is tough. In order to make them soak in loose rocks, the high-speed compression has to be very low, very diggressive. You can't change the high-speed damping with clickers, you have to revalve it.

Loosening the rebound might help. But, as I remember, the stock 4CS already has such a loose rebound that the forks often top out and clunk. Again, you need the high-speed rebound damping to be low, not the low-speed.

I would say, send your suspension to Kreft Moto. They know all about 4CS and how to make them work on loose and slippery rocks. I wouldn't trust them with an MX/SX setup, but the woods stuff they know very well. It would cost you though, but you may get the best suspension that you have ever owned.

P.S. Don't tell them I sent you. Say you read reviews on KTMtalk. Also, wait for the coronavirus related shipping delays to end, else it may take way longer than anticipated.

 

[Oded]

You are right about forks top out and clunk.
Can't send it to the US, but we have some pro suspension specialists around here. Will give it a try.