BOS Devilles – Air Pressure

Back from my 2nd run on them today (round the W2 at Afan). Felt pretty good but a little firm. Thought I’d let a little air pressure out.

Turns out they were way below the manual recommendation already.

If I run anywhere near the recommended air presure the forks are way too firm (on a quick ride around the garden)

I need to run around 50% of the recommendation to get them feeling like they will move (which gets me pretty close to the minimum they say is acceptable). Even then I get no where like the sag I would expect.

I am fine doing this but wanted to check if this is common or if the forks potentially have an issue.

Also wondering if this is a bedding in process

Any help / advice appreciated

No idea about the BOS but with various RS forks and Fox shocks I’ve found exactly that. I need to run about 70% of the recommended pressures.

Big thing with the devilles is that you must gently cycle the fork after setting the air pressure in order for the chambers to equalise and the fork work properly. If you don’t then it just feels awful and over sprung. Roger at R53 underlined the point to me several times as a lot of people had been having this problem and thinking the fork was awful.

Geetee

Is this the move it 10mm gentle up and down a few times after you are done thing? Did that but will rest and have another go

Are you running close to the recommeded pressure?

Is this the move it 10mm gentle up and down a few times after you are done thing? Did that but will rest and have another go

Well Roger didn’t specify how much to move the fork, just to cycle it gently and I guess I moved it maybe 20mm? Not sure if that would make a difference but it might.

As for whether I am running recommended pressure, yes and no. I run it a little softer in order to get the ride height a little lower but that’s a bike set up issue not a fork set up issue.

I don’t ever find them firm but they are not as ready to use their travel as other forks I’ve used. Subsequently I rarely if ever bottom them out, even though I am running them quite soft.

Setting up forks is a bit of a dark art in my view anyway. The whole sag measurement is very misleading because how much sag you will get will depend entirely on where you are on the bike. JRA you might get 15% but get forward a little and you may end up with the equivalent of 30%.

The other thing to experiment with is the low and high speed compression. These really make their presence felt when you start to adjust them. Try running the fork at the recommended pressure but wind a lot of both high and low speed compression off and see how that works.

For me the stock settings felt great. They feel a lot softer and faster than other forks have been at stock settings but much better for it.

Thanks Guys

Steve was that straight out the box?

Geetee – your recommendations have helped but they are still super firm even at a much lower than recommended pressure. I usually run a spring rate up in my coil forks (firm rather than Medium) so I do tend towards firmer settings.

Another bed in ride tomorrow and if they still feel pretty firm at around 50% of recommended pressure then I will call R53 on Monday

I’m about 80kg with gear on. Currently running about 80psi. Current settings are +1 rebound, +1 to 2 slow speed compression and -1 to 2 high speed. Gives about 30% sag but would need to check to confirm.

Your experience does not sound right.

Equalise method I was given was:
Let all air out
Pump up to 3.5bar, stroke shock slowly about 15mm 5 times,
Pump up further to 5 bar and stroke again,
Pump up to 7 bar and stroke again,
Pump up to 9 bar and stroke again,

Lower to riding pressure and stroke again. This is where you have to be careful as every time you change the pressure a little to find the sag/pressure you want you should stoke the shock 15mm a few times.

I was under the impression the equalisation was required for damping to work properly, not sure if this should really effect your static sag settings. I would let all the air out and start over, good luck 🙂

I found mine to be much firmer feeling than most forks; my TRC knob was on the wrong way round (meaning when it was meant to be off it was actually on) which made them feel firmer but this is easy to remedy. As mentioned, careful cycling of the forks after adjustment really pays dividends.

Their slow speed damping seems quite stiff compared to RS, fox & Marzocchi, but when you’re caning it, they feel fantastic.

Also worth noting that BOS have mixed themselves up between the manual and the stickers on the fork. All 3 damping types increase when wound clockwise.

Sorry to hijack this thread, but my trc sticker is different from the instruction manual too (and trc ‘on’ vs. trc ‘off’ is not that informative – twin rate curve = on; what does that mean?? travel reduction on/off would be easier to understand.

So, with the trc lever fwd, is that travel reduction on or off?

Also, Mr Plow, do your ‘+1’ settings mean +1 click from the starting point recommended in the manual?

Thanks in advance!!

So, with the trc lever fwd, is that travel reduction on or off?

With the lever forward, i.e. rotated clockwise, the travel reduction is on. Bear in mind that the travel reduction only takes place at the end of the travel, not the start, so the fork stays the same height whether the TRC is on or off. This is different to how other forks typically achieve this but it means you can reduce the travel without changing the geometry. It’s very useful on slow steep terrain where you don’t want the front end to drop.

Also not that you can easily remove the lever and rotate it to a different position, which helps with clearance of the downtube. The on/off position still remains relatively the same though; rotated forward/clockwise for on and reverse for off.

Beb – my settings are + or – from the std 15 turns clockwise on all dials. Should have made that clear. I do not have TRC. I still have to spend more time doing proper bracketing on the settings but straight off these are a nice starting point for me.

Too ill to ride or this would have been my mission this weekend.

Thanks all

Been through all the recommendations above several times (appreciate all the pointers). Alas the end result is that they are still way too firm. Now used 3 different shock pumps to make sure I had the right readings.

Even with no air in there they are pretty firm. Guessing that they would be close to correct sag with no air?

Basically seems like there is an issue. Will hopefully get it resolved quickly by R53, otherwise my easter w/e riding plans will take a hit 🙁 . Will be pretty angry if that is the case after shelling out that much cash.

Will keep you posted

It’s pretty obvious when TRC is on as the fork ramps massively, if you can’t detect the difference then you must be insensitive to fork settings and I would recommend you stick to default settings which are close to spot on in my experience. My manual has it the wrong way round too but its obvious when you ride them.
I do find that they are a harder than other forks and really perform there best when being ridden hard. For pootling around they aren’t ultra plush coping with bumps but nail them fast over roots and what not and they are awesome. I tired dropping air pressure to make hem softer but they just loose their composure and become prone to dive.
After a couple of years on them I’m now back to running standard pressure, a couple of clicks more LSC and a click or two less HSC. TRC was never turned on and I found pretty useless as most of my riding is downwards.
Edit: looks like mrplow and I run similar compression settings but I run less sag at 20%.

nice one thanks guys.

I was pretty sure lever fwd is reduced air volume but wanted to make sure as the manual says the opposite. I’ve not had much call to use the trc to be honest so haven’t really bothered with it, but thought it’d be useful on steep slow techy downs, not that there are many (any) of those in western australia it seems 🙁

I’ve done a bit of playing with the damping settings too as have found they can be a bit harsh for me on high speed bigger hits with the standard settings and ended up backing off the HSC a bit as a result.

Taz, sorry for the hijack and hope you get your forks sorted soon, does sound like you’ve got an issue if they’re still firm with no air in! When they’re working they are great; super composed as everyone says.

cheers

No worries at all Beb and thanks for the comments. The TRC discussion was helpful for me as well. I debated if I needed it and opted not to go for it as I doubted I would use it

Are you sure you are doing the chamber balancing right? also note that when you “let all the air out” with the shock pump, thats only out of the top chamber. If you then do the slow cycle 10mm up and down a few times and put the pump back on you will see the pump now registering pressure again, 10psi or so down from before you first dumped the air out

I run mine 10psi or so under what the manual recommends for my weight and also with the low speed backed off about another 5 else they are not great on bumpy flat trails, get the moving however or downhill and they are brilliant

Yes dlr I did that cycling as I emptied the air pressure as well and your right it took a few releases to clear it

However I think the source of the issue has been a very, very tight seal. As I was heading out today it completely pulled away from the top of the lowers and was ‘stuck’ on the stanchion (air chamber side)

This was very clsoe to home so went home lubed the seals up and pushed it back into place. Then I needed to set the run the air pressure at the recommended level.

Now I have a totally differnt issue. The seal is popping up periodically – stopped me going out today as I did not want to risk it coming away un noticed and dirt getting into the fork. Any one have tips on what I need to do to get it to stay put?