Fox 38 Harshness?

[Nomadic Dad]

But are you using around 80% of the travel on your fork on your regular trails? If not, you have too much air pressure and you are not using your fork as much as you could. If you are bottoming out on hard hits, then add HSC and volume spacers. I weigh around 80kg and run my Fox 38 at 75 PSI with 1 volume spacer and a Luftkappe Air Piston Kit which I found reduced the harshness and added mid stroke support on the trails I ride.

Yes around 80% of travel on my local trail centre red and blacks I've done my initial testing on. I will mess with compression and check for any bottoming out when I ride some larger drops and jumps next weekend at the Golfie / Glentress.

 

[Mikerb]

I think I have seen those videos suggesting keeping high and low compression open.......but that tester seems to do that on all forks! I think it is a mistake even for a very light rider because it is not allowing the damper to operate as designed. Certainly a light rider on mild trails. May need very little high speed compression but should set low speed near to a middle setting. It is often the rebound setting that makes the fork seem too firm.

 

[Christurbo]

I think I have seen those videos suggesting keeping high and low compression open.......but that tester seems to do that on all forks! I think it is a mistake even for a very light rider because it is not allowing the damper to operate as designed. Certainly a light rider on mild trails. May need very little high speed compression but should set low speed near to a middle setting. It is often the rebound setting that makes the fork seem too firm.

Correct, if you run LSC open then the fork will sit further into its stroke which will make it feel firmer. Which then most folk will try adjusting the rebound. Suspension is more plusher if it sits higher in an air shock.

 

[TimC7]

Correct, if you run LSC open then the fork will sit further into its stroke which will make it feel firmer. Which then most folk will try adjusting the rebound. Suspension is more plusher if it sits higher in an air shock.

I thought preload/air pressure set the sag?

 

[Christurbo]

I thought preload/air pressure set the sag?

It does, my comment was geared to the setup once sag was set. E.g. misconception about running LSC fully open to try and get buttery smooth plushness.

Edit - spring rate sets the sag on a coil. That’s what takes the time and effort. Worth it though when you get something that works for you.

 

[TimC7]

Doesn't rebound make more difference? Too much and the shock won't recover in time for the next bump, too little and it bounces back past the static point. Compression damping makes it feel soft/firm.

 

[Christurbo]

Doesn't rebound make more difference? Too much and the shock won't recover in time for the next bump, too little and it bounces back past the static point. Compression damping makes it feel soft/firm.

Just found this for you. A lot easier to explain if you watch it. I think they demonstrated my points perfectly.

 

[Mikerb]

Good video. He purposely focuses on the damper functions to keep things simple but of course the range of adjustment of both compression and rebound are working on the progressive spring rate that is set initially by setting SAG. The damper tune will determine just how much compression and rebound it can offer. With a fork designed for hard riding enduro such as the 38, that tune is likely to provide higher rates of both than say a Fox 36. It makes sense therefore to set a relatively high spring rate and it is a spring rate set too low that will lead to setting adjustments too open on the damper. You can set SAG anywhere between 15% and 30% but both will provide fairly plush movement in the initial part of the stroke. So it is a balance that needs to be achieved between spring rate and compression/rebound.
The a bove is then complicated somewhat by the use of tokens/spacers. So another balancing act to be achieved there!
Experimentation is the only answer.

One topic not covered in many videos on suspension tuning is the effect on tuning of the amount of travel in the fork. So comparing a 180mm fork with a 160mm, both with the same rate of progression, the 180mm will have a larger section of initial fork travel that is plush ( least compression of the air).

My head hurts now!!

 

[Husky430]

Have found my 38s much less compliant than the 36s on my previous bike unfortunately. To the point where the clickers, didn't matter which, HSC, LSC, HSR, or LSR made any difference. As still under warranty LBS sent them back to FOX for their professional opinion. After some tooing and froing with the mechanic at the local bike shop he asked if I was OK talking direct with Fox themselves, which I agreed too.
Talked to them and they said, rather conveniently, that there was nothing wrong with them and that the 38's where completely different to the 36s and that the clickers didn't make as much difference as before with the 36s. Also that with the 36s you basically put the same amount of air as your weight in kgs and that the 38s need about 15psi above your weight. Also they come with 3 volume spacers and that for my riding I could probably loose one of them.
So they serviced them and took out a token and I tried their settings, not the huge change I was hoping for and they are still harsh in the initial part of the stroke, but they do now stand up better and don't dive under breaking hard into corners etc but still HARSH compared to the 36s.

 

[Nomadic Dad]

I think it's very evident from all the various discussions, chats and even video posted on this thread that setting the 38s up is complicated and you need to be prepared to spend a great deal of time testing one change at a time as every change affects the others. If I've learned anything from all this then it's vital to get your sag right first with everything open before messing with anything else

I'm going to try my LSC half way this weekend rather than fully open to see if the fork sits higher in the travel longer as I can see the logic in doing this. However, I will will leave my HSR and LSR as they were and where I was happy with them on local red and black trails but I'm fully prepared for these now not to be correct if I'm closing the LSC a bit.

Given all the above, can we all agree the following is the order we should do things on forks in general?

1. Set sag
2. Add a volume spacer if you blow through the travel at the correct sag or remove 1 if you don't get to 80 - 90% of travel at the correct sag
3. Adjust LSC - if you are blowing through the middle 1/3 of your compression or diving too easily on slower compressions like corners and braking. Close it a few clicks to make it firmer or open a few clicks to go through the travel easier and make it more sensitive / stable
4. Adjust HSC if you have it - all to do with the travel you use hitting larger bumps and drops
5. Adjust LSR - open this (speed it up) for tracking high frequency features quicker i.e. make it more sensitive
6. Adjust HSR if you have it - this is related to the end stroke and when using most of the travel or the speed of recovery from larger deep in the travel impacts.

 

[Mikerb]

I think it's very evident from all the various discussions, chats and even video posted on this thread that setting the 38s up is complicated and you need to be prepared to spend a great deal of time testing one change at a time as every change affects the others. If I've learned anything from all this then it's vital to get your sag right first with everything open before messing with anything else

I'm going to try my LSC half way this weekend rather than fully open to see if the fork sits higher in the travel longer as I can see the logic in doing this. However, I will will leave my HSR and LSR as they were and where I was happy with them on local red and black trails but I'm fully prepared for these now not to be correct if I'm closing the LSC a bit.

Given all the above, can we all agree the following is the order we should do things on forks in general?

1. Set sag
2. Add a volume spacer if you blow through the travel at the correct sag or remove 1 if you don't get to 80 - 90% of travel at the correct sag
3. Adjust LSC - if you are blowing through the middle 1/3 of your compression or diving too easily on slower compressions like corners and braking. Close it a few clicks to make it firmer or open a few clicks to go through the travel easier and make it more sensitive / stable
4. Adjust HSC if you have it - all to do with the travel you use hitting larger bumps and drops
5. Adjust LSR - open this (speed it up) for tracking high frequency features quicker i.e. make it more sensitive
6. Adjust HSR if you have it - this is related to the end stroke and when using most of the travel or the speed of recovery from larger deep in the travel impacts.

Nothing wrong with that process but take note of a couple of suggestions:-
1. you say set SAG......but there is a pretty wide range of SAG settings to aim for. Anything from 15% to 30%. So maybe choose a middle ground initiallly.........say 20%.
2.You also need to decide on how many spacers to use. Personally I would start with 2 unless you are a big fella.
3. you need to know what your reference point is when playing with the damper settings. So maybe start with LSC/LSR on a middle setting. HSC/HSR is easier to set because you leave them fully open whilst you ride flow trails etc, then try different settings for a trail with G outs, drops, jumps etc with them on a middle setting to start with.

ps it took me 6 months of trial and error to set up my 38s how they are now and I cant fault them.

 

[Durrti]

I had fits with my 38, super harsh through medium chatter. Decent off the top. Had a sucked airspring, fixed, still garbage. Smashpot installed, better, still arm pump like crazy!
New Zeb installed and it’s glorious!!
Not trying to flame, just my honest experience