I recently bought a Trek Fuel EX9.8 that comes with Fox F120RL forks and I’m having real trouble getting sensible travel out of them. The rear end’s proper plush but the forks aren’t cutting it. I’ve tried adjusting the sag and this is what I get:

20-25mm sag I get about 75mm travel including sag. Not very plush but controlled

30mm sag I get about 85mm travel but 5mm of that has been eaten up by the sag and the travel blows through making the fork harsh on mid-sized hits – the fork would need compression damping to make this setting work

I’ve read elsewhere that removing a couple of cc of oil from the air chamber can increase travel by up to 20mm and will give this a go but does anyone else have any experience with this fork and any similar problems or can anyone report wonderful performance?

I’ve come from a DT Swiss EXC150 which was plush and had both compression and rebound damping that enabled me to fine tune the ride. I miss it but hope there’s a way to get better performance from the Fox.

I have these forks and have the same problem – I can’t get the last 20 or 25mm of travel, with the sag set correctly. I have to make the forks much much softer and then they (obviously) blow through the travel and bottom out.

I asked about this on here previously, and didn’t get much help. Should probably contact Mojo really but haven’t bothered yet…

apparently there is a fix
changing the cartidge it cost 100€

**** that! 120mm forks should give 120mm of travel from new, without paying for a ‘fix’.

Exactly! I can’t believe that Fox can get away with this. I’m surprised Chipps hasn’t mentioned anything about this problem with his Fuel EX9.8 – any comments Chipps?

I’m surprised Chipps hasn’t mentioned anything about this problem with his Fuel EX9.8 – any comments Chipps?

Do you really believe the forks journalists got are the same that people buy in shops?

I tried removing a couple of cc of oil from the air chamber as suggested by Fox to another owner with these problems and the result is noticeably less dramatic ramp-up but still only 80mm of travel for 27mm of sag. That’s what I had with my Marzocchi Marathons in 2002!

Will call Wheelbase, where I bought the bike, and see what they have to say.

Perhaps you should get off the towpath guys.

<And ducks>

Must measure how much travel I get from my f120RLs tomorrow. I’ve noticed that it doesn’t look like a full 120mm but haven’t been too concerned by it.

I’ve got 120RLs and use 33% sag and get the full travel if I push them. TBH they feel far too stiff with anything less than that as sag. Have 50% sag on my talas 36.

20-25mm is just not enough

IIRC you can trim the pushrods down a bit to increase the size of the chamber and reduce the ramp up

edit: here

I have the same issue with mine that came on a Scott Spark i brought 2 months ago….. Only getting 70mm out of them

Djglover, thanks for your experiences, however, as with so many forum posts, this information is of limited value without some understanding of what you ride, how you ride and where you ride.

Additionally, you need to understand the limitations of setting sag as a way of setting up a fork. Sag is a static measurement and, unfortunately, mountain biking is a very dynamic sport. The effect of sag will depend on how you ride. For instance, I ride longer distances and I ride fast. Most of my riding is around Hampshire where I live but I get to The Lakes, The Dales and Wales several times a year. Because I ride long distances fast I use bar ends which enable me to change my hand position and give me more speed on the flat and on climbs. Because I use bar ends and I’m usually in a fairly aggressive position my weight is shifted forwards when I’m riding relative to the more centred position I might take when measuring static sag.

The upshot is that as soon as I start moving my 27mm of static sag turns into about 35mm+ of what we might term ‘dynamic sag’. This has the effect of steepening the head angle and reducing the height of the bottom bracket. If I set 30-35mm of static sag then my head angle is way too steep and my pedals too readily bottom in tractor ruts (of which there are many around here).

It may be that you have a very high stem, bar, stack combo and you ride a more upright position which enables you to use more static sag since much of your weight is on the rear of your bike and it may be that you ride relatively short (say upto 20 miles), playful rides where speed is of limited importance, ditto long distance comfort and that you’re more interested in big hit response than initial and mid-travel response which will blow through more quickly with 33% or 50% static sag.

You should also bear in mind that 33% sag means you only start with, at best, 80mm of potential travel. ‘Dynamic sag’ will likely reduce that to 70mm and the bump stops and ramp-up will reduce it further to 55-60mm. So, you’re getting no more travel than I am and you’re likley to be suffering from an unacceptably steepened head angle and poor small to medium bump absorption as a trade off for better big hit response, though still with incredibly limited travel.

Running 50% sag means that you’re running a very steep head angle and getting very limited travel though your front end will pogo nicely, if that’s what you want.

In essence you’re working around a problem with the overly simple design of your Fox forks which do not have a design that manages the spring rate of the air chamber effectively.

Feel free to disagree but please provide a considered reasoning.

Juan – do you think the fork companies produce a ltd run of ‘journo only’ products!!!
There seems to be a lot of analysis and ‘tear it apart and fix it’ advice when all you need to do is take it back to the shop and ask them to warranty it. If you start tinkering with it you will invalidate any potential warranty claim.
Job done.

Same problem here. I never get them anywhere near full travel. At most the run 90mm. Say that though I’ve never mnaged to get full travel out of any fork, Fox, Rockshox, Marzocchi….. Maybe you’re not meant to ?!

Ignore the sag, this is about travel. I have an F120. At recommended shock pressure for my weight, from top (un-weighted) to bottom (the most severe compression) it only manages approx 100mm of travel.

But it’s a nicely controlled 100mm.

Buzz-lightyear, 100mm of travel would be entirely acceptable as the bump stops will always make the last 10mm almost impossible to use, which is entirely correct as you really don’t want the fork bottoming out harshly, and the last 10mm of ramp-up before that will be incredibly firm as the air will have been compressed to an amazingly small volume by that time.

The fact that you get 100mm of travel would indicate that there is considerably variability between forks as several people, including myself, seem to be unable to get that sort of travel without setting a silly amount of sag. It’s good to know that someone’s got a decent pair!

Martyntr, as I outlined above, I agree that you’ll never get full travel but I’d expect to get 100mm and I’m nowhere near it. My previous DT Swiss EXC150s gave about 125mm of travel without setting them too soft and were much more tunable thanks to the combination of compression and rebound damping. I suspect that the F120RLC would be configurable to give about 100mm of travel as you could set greater sag on that fork without overly compromising small to mid-bump absorption by increasing compression damping.

It may just be that the F120RL is simply too compromised. You can have travel but only at the expense of control and vice-versa.

Well I wouldn’t be very surprised if the stuff send to jounalist woul dbe different.

It’s not a warranty job as they will say that it’s due to the ramp up as a safe last 20 mm bla bla bla.

To be honest the float are the only fork I had on which I never get full travel.

I’ll probably cut the rod tomorrow if I got time
I’ll post some picture.

Just cut about 20 mm out of the rod.

Put the same pressure and tried it static in the garage.

Still can’t get the full travel. However, for the same SAG and travel, the fork seems a lot more linear. I’ll try to see if removing the last 10mm does help or not and by actually putting 5CC of oil and not about 3 taps…

Just cut about 20 mm out of the rod

brave dude! who cares about 20mm though? If the fork is plush and damped well + the head angle is OK. Does it really matter if you’re getting 4/5″ [oooer]?

I find steering stiffness more of a problem then travel with the QR version.

bloody hell – its a shame bikes dont come fitted with flex stems these days – you kids dont know your born.

I have never bothered to measure the travel on my RL100 RLC 120 or Talas – they all feel superb compared to what I have had in the past:

Pace RC31
Indy SL
SID hyrda air…

bwakel – I ride a whyte 905, 90mm stem fairly low stack height, in the Surrey Hills, Chilterns ans lakes so far.

I think you are too hung up on the sag issue to be honest. I raced DH (and did pretty well) for several years and sag set up was 50% on 200mm forks meaning, by your logic, you have 100mm of travel. Thats simply not true, as you need the sagged travel to use when the ground drops away, lots of sag is important, jack your car up and see how much your car wheels have – and thats for the road.

And the front end doesn’t pogo at all, there is enough rebound control on the fox to make it very controlled

djglover, yes, you’re quite right, I was being deliberately simplistic with my analysis of travel, though I’d argue that you only need 50% of negative travel if you’re doing downhill. I still think that there’s a limited amount of usable travel with the F120RL and it’s the same amount whether you have lots of sag or not so much, all you’re doing is affecting what sort of response you get to different sized hits.

Fotorat, I’ve been MTBing for 19 years and remember my first bike was steel had rigid forks (nasty, difficult to remember how much it hurt!) then RockShox Quadras (pointless), then Ronds (actually very good even compared with modern forks but leaky), Pace RC38s (very good for 5 minutes then they leaked constantly), Marzocchi Marathon S (very good but very fiddly to get right) and finally the DT Swiss EXC150s that were on my Yeti which was nicked last month. You’re right about the progression in quality. My complaint about the F120RLs isn’t so much that they only have 80mm of travel – if they worked as well as the fantastic rear end on my Trek Fuel EX9.8 I wouldn’t be bothered for a minute – it’s the fact that they’re letting the bike down that’s annoying me.

Be interesting to see how you get on Juan!

Been reading this with interest as I bought a new bike last week which has these forks on it.
My first thought after a ride on Thursday was that the forks didn’t seem to have much travel compared to my previous forks but that the difference was only 5mm – Fox F120RL vs Fox Vanilla 125R.
I don’t think people are imagining this – there definitely seems to be a lack of travel on this fork. Going to experiment with sag/air pressure but if it doesn’t resolve the issue then will go back to the retailer.

Cutting the rod is not increasing the travel, but making the air chamber much bigger, thus allowing a less ramp up behaviour.

To be honest it almost all went smooth. Took me about 40 minute and would have been just great if it wasn’t for my spanner ripping :'(…

If you aint getting full travel then you aint riding hard enough. **** the fork, concentrate on the skills.

Juan, thanks for the spanner work, at least it saved everyone else from trying!

garlic, I can only say that I’m glad that people like you don’t develop MTB products or we’d all still be riding steel rigid hardtails with five gears but paying £3K for the priviledge. Why can’t we have skills and decent kit or can you only think about one thing at a time? Do you think Steve Peat would be competitive on a steel hard tail? Nope. Why do you think he spends so long developing and tuning his kit as well as his skills?

I have some F120RLs and they’re fine. I’m 13.5 stone and run them with around 35% sag. I get full travel most rides, be it bumbling along relatively smooth and easy xc through to doing drops over 6ft. All without any changes in the setup and they don’t hard bottom. As far as I can tell from the Fox forks I’ve owned, they rely on very good speed sensitive damping to control the bigger hits and without the correct sag, you will get an awful ride.

I initially setup these 120s with 25% sag and suffer the exact same issue. The same was for my 36s I had previously on another bike, it’s just the way fox ride and it’s very different to other makes.

IIRC this has been rumbling on as an issue for several years, especially with the TALAS(130) which never seems to get into the last 20mm. I have an 06 and i’ve never got anywhere near the full travel, even when inadvertantly hucking in the alps. Having said that the over all ride quality of the fork is far better than others i have used. The manitou minutes thay replaced where great on big hits but where hopeless on climbs and were made of cheese. My prvous f80/f100’s never got full travel either, but then they were on race bikes and arguably 50mm was enough.

Thanks Solamanda, I’m just going out for a ride now so I’ll try running around 33% sag as you and djglover have recommended. It feels wrong and I’m concerned that it’ll feel like I’m in a nose-dive on the flat but I’m willing to give it go. I’ll report back later.

How much sag are you running at the rear? Those fuels do ride well with 33% sag at the back and if you are running less, it will feel like you are going over the bars. Also try running the rear rebound quite slow, I run my EX8 a couple clicks off slowest.

Garlic come over here you’ll how hard I ride 😉
Right I am off trying to get pictures on flickr so I can do a how to thread.

Solamanda, I was running about 25% sag on the rear but as I increased the front sag to 30% today (after some experimentation this seems to be best for me) I increased the rear sag to 30% too. What a difference! The bike feels nicely balanced and the fork is responsive without being draining and it’s not blowing through it’s travel too quickly. The rear end is super smooth and traction is excellent, even on a one mile climb on gravel-covered single track that nearly killed me.

Downsides? Brake dive is severe – even with the Active Brake Pivot, the rear end was off the ground following a couple of emergency stops where I missed a turning. And the fork’s sitting a long way into its travel and, guess what, maximum travel is still only 85mm! So I really don’t have much travel helping me over obstacles. Still, the bike felt fun and was very fast compared with last weekend. There were no really big hits on today’s route so it may be that a crash landing will highlight some more travel.

So, the quest for more travel continues but the forks do seem to prefer a fair amount of sag to get them active.