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Got a Fox 34 with Fit4 damper performance model so no compression adjustment just the 3 position switch, always running in Open. A while back I upped the travel to 150 and figured I might as well get the bigger negative chamber with the 2019 NA2 EVOL airshaft as it retrofits into my 34.
Maybe all placebo but it did seem to feel a little better/softer in the beginning part of the travel.
I'm not really all that fast yet (working on it and signs of improvement!) I'm starting to manage to find more time to devote to riding and making it more regular (mainly around Haldon forest at the mo, but itching to hit FoD soon) and now I'm starting to think that there is a tiny bit of harshness/spikiness in the fork on the faster stuff especially as the hits start to get bigger than just the usual trail chatter. On the back I've got a bog standard DPS but it just feels great and seems to be just dialled for me and my namby-pambying around no need to mess with that at all. IT definitely feels like its doing a better job than the 34 up front
Oh Im around 75kg on a medium canyon spectral
Would adding a Luftkappe to get even more negative chamber along with the already installed NA2 EVOL airshaft to make the initial stroke even softer make things better or worse?
Any thoughts guys? Or am I just having misinformed expectations from my 34?
The way I understand it, re-valving the fork to have a teency bit lighter compression damping would take a bit of that harshness off, is that right? I know that's going to be a fairly pricy procedure so is it even worth doing at my level? There's old chats on the forums about the E16 tune versus the E18 tune for these forks when swapping to NA2 EVOL airshaft. The E18 is supposed to be a bit softer. Looking through the shim stacks the only change they've done from E16 to E18 is remove TWO of the 0.7 diameter shims and replaced them with ONE larger 0.8 diameter shim.
I could get that done at some point when I get my fork looked at for a damper rebuild if the squishy/squelchy/whooshy noise (on the rebound stroke) starts to get too much! As it seems to be a reasonable price at RSF in Plymouth if I needed maintenance work done anyway.
You're trying to fix a damping problem, by increasing the volume of the negative air spring...? 🤷🏻♂️
It doesn't work like that...
I'm 90kg, never got on with FIT4 as found it a bit harsh and the range of adjustment unusable (don't get me started on RC2!)... Either get it revalved and/or use a much lighter oil in the damper to compensate, or **** it off entirely... GRIP2 for Fox 34's is on its way, this damper is a massive step on for sure.
However... @ 150mm, part of the problem is the 34 is a bit out of its depth anyway. A fine fork @ 120mm travel (my 34SC Performance on my XC bike is superb!), once you're up to 150mm there's all sorts of other issues creeping in from a lack of chassis stifness etc.
If you're going to spend money on the bike, I'd suggest saving up and getting a more modern Fox 36 fitted on there with either the Performance level GRIP damper, or preferably the Factory level GRIP2 damper fitted... It'll be worth the outlay for sure!
You’re trying to fix a damping problem, by increasing the volume of the negative air spring…?
Haha you do realise that a lot of us have no idea what we are talking about and most of our ideas are derived from armchair engineering degrees! 😀
I agree that 150 is kinda pushing it on that 34. And I could be getting issues related to binding and increased friction from the twisting and flex. This bike is my training bike to push my fitness and skill level and of course boost my confidence levels. So my intention is to thrash it to pieces to get betterer and next year think about a shiny new bike purchase so I probably shouldn't go around buying a new fork for it as I don't know if next year I would want to go from a 27 to 29er. Whatever suits me is what I will get I'm not a die hard fan of any one thing over another. I will only know what works the more I ride.
My line of thinking with the negative spring increase was: I reckon the harshness is a function of rate of change of oil flow velocity through the ports (ie the force the oil exerts on the shim stack) versus the resistance it meets from the shim stack.
ie when the oil velocity suddenly changes up thats what we feel as harshness (sharp transition from lower force to higher force)? SO I was thinking that if I soften up the initial travel the oil is having less resistance to accelerate faster through the port which means its flowing that little bit faster (more force exerted) by the time it gets to mid stroke so there is less of a change of velocity (to higher force exerted) so a smoother transition into the higher part of resistance from the rest of the shim stack? which means slightly reduced harshness?
I accept I could be completely wrong in this way of thinking. which is why Im asking in this forum cos I need edumecating! I want to improve massively as a rider, my fitness and skill are two very important aspects so I got to just devote more time to that that but I also reckon learning to know and understand the equipment you are using is an important part of that. What changes have what kind of impact etc hence all these types of questions.
I probably will just re-valve when I get round to having the damper looked if the squishy sounds change but I'm interested in the conversation and other peoples thoughts on the subject so keep em coming
or use a much lighter oil in the damper to compensate
Anyone know the cSt values for Fox R3 5wt? The usual sources of info don't seem to list any of the Fox oils
You’re trying to fix a damping problem, by increasing the volume of the negative air spring…? ..... I’m 90kg, never got on with FIT4 as found it a bit harsh and the range of adjustment unusable
I have one in my 2016 36's and I'm 75kg. Converting to an independent neg air with the MRP kit (as advised here) makes these good for me. More surprisingly with more or less the Fox recommended settings... it might just be because I'm a decidedly average rider but these don't feel "less good" than my Lyric Ultimate RC2's though they are only set at 160mm.
Are all Fit4 dampers the same?
I have the 2017 34 Performance Elite which came with the Evol air shaft, and I've never found it lacking (140mm and now 130mm on newer frame).
It's not as plush as my Lyriks, but always copes well with rugged terrain, e.g. Lakes, Pennines.
When did it last have a service? Was it a while ago and you've noticed the harshness recently?
Motorex 2.5wt fork oil is very close in spec to Fox R3
Theres also this-
https://j-techsuspension.co.uk/products/andreani-piston-kit
Fully serviced when the airshaft got changed with new SKF seals. So its probably 6-7 rides in.
A few weeks ago I did a session with Tony Williams @Evolve MTB and I'm intentionally attacking stuff a lot harder and faster than I was before, keeping off the brakes more seeing how much more I can ride out without slowing down. It could just be that is how these forks are and I've read too many reviews of spangly new forks and twisted my head with dreams of magic carpet plushness, lol
I can feel some amount of pushback from the terrain through my hands on the bars when hitting the bumps. hard to quantify.
So if Motorex 2.5wt is similiar to Fox R3 5wt that puts it around the 15ish cSt viscosity. So would switching to something at 14cSt (Maxima racing light 3wt) be a really noticeable difference or maybe even lighter down to 13.6cST (Silkolene Pro 2.5Wt)
I've got some OEM 2018 Fox 36 Performance forks with are GRIP FIT4 (IIRC) which I've found quite spikey and 'wooden' and in which I've had a Luftkappe fitted to try and make small bump sensitivity better - and I can't honestly say I can tell any difference.
Not sure if it's my imagination or not but they seem to start off a ride ok and then get worse. They are recently serviced and in mint condition overall. I also have some 2017 (I think) Rhythm 34s which I got in a PSA on here from Germany and they are much better, really nice actually, but only 130 travel.
Not particularly helpful expect to say that my experience is that (as per the earlier comment) the Luftkappe doesn't make much difference if your damping control isn't great to start with.