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Reba Dual Air
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
Has anyone had trouble setting up Reba dual air forks, I just can't seem to get mine right? The Fox forks on my old bike, 5 years old, seem to give a much better ride than my newer Rebas.
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Yes geoff - dual air is too complicated for us simple folk - (cue banjo playing)
the numbers on the leg seem way too much pressure - despite the instructions, a bit below the recomended pressures for the top side, and a solid 15psi at least in the negative chamber brings them more into balance on mine - ie decent small bump, but not so soft as to send you over the bars at the first opportunity.
Second - the bastards of things have foam oil rings in them that drain of oil if you leave the thing right way up - store bike hanging or upside down, and everything is plush - store it upright, and the oil stays away from the stanchions.
Most people seem to set the pressure down on recomended - (for me thats 95psi rather than recomended 130psi) in both + and -, and leave em there. Hence this years models are single air, which means both chambers are the same.
Yeah they take a bit of getting adjusted correctly. Like Pharmaboy writes - the standard pressures seem a bit high and need to reduce them to get the correct sag and a better ride, for me that's 10psi less then the lower 'recommended' pressure. Suggest you start by having both - and + the same pressure to begin with. Use the o-rings on the forks and shock to get the sag in the ball park. make sure you have the 'brain' (compression) fully open when setting the sag. (both for shock and forks).
Just one addition to what Pharmboy wrote, Fox/Specialized state "Negative air pressure should not exceed positive air pressure by more than 15 psi (1.0 Bar)".
Older forks tended to be set and forget, but the new forks, especially dual air, can be finicky to set up, another reason Fox did away with the 'dual air'.
I assume you have the instruction booklet to go with the fork? The brain forks booklet is available from specialized web site - don't think Fox has it on their site.
When you say your old fork was a 'much better ride' in what way better?
I've had many sets of Dual Airs (5 including my current Revs), and currently run Revelation WC Dual airs on my 5.7C.
They do take a bit of effort to set up, but once you find the right settings for you, they're amazing! The best place to start is to set sag, using equal pressure in both the + and - chambers. Once you've found your sag pressure, you can tweak the pressures a bit and find your sweet spot.
When I had Rebas (2007 on my '07 Trance and 2010 on my Mach4), I had the + pressure set a bit lower than the guide (same as the post above), and would run the - pressure about 5psi higher than the + chamber. This gave me great Small Bump compliance without too much brake dive.
I still run about the same pressure differential on my Revs, unless I'm heading into a "big hit" day on the bike. At that point I drop the - pressure to equal, or a bit below, the + pressure, so that it takes a bit more to use the travel. That theory also works if you're going to be doing lots of street Km's on the bike, and want a better fork for pedalling.
Probably one of the best investments I made was to get a shock pump with a 2-stage connection. As the - chamber is so small, even the slight loss on disconnection of a normal shock pump dropped the pressure quite a lot. With the 2-stage shockpump, you can be sure the pressure you set is the pressure that stays
I've personally got a Topeak one, but a mate has a BBB version which also works great.
If you've got any questions, let me know and I'll happily answer what I can
The Fox fork seems to absorb bumps better, it's more active.
Sounds like it's not quite setup correctly then to be honest. The general gist is that having the Negative chamber with a higher PSI (compared to the Positive chamber) will result in better small bump compliance, and a more plush fork. The downside though is that too much Negative pressure and the fork will dive too much under brakes and bodyweight.
Less PSI in the Negative chamber (compared to the Pos) will result in a stiffer fork initially and one that won't use the travel quite as readily (which can be a positive thing
), but won't absorb the small bumps as easily.
Try setting the Neg chamber a few PSI higher than the Pos chamber. Definitely experiment until you find your sweet spot!
oops meant rockshox not fox in previous post
. Then having your "negative" air pressure higher than the "positive air pressure wil make the fork more active.
extract from manual
"Step 2 - Selecting Negative Air Pressure
Negative air pressure affects the amount of force required to initiate suspension travel.
Negative air pressure works in combination with ground bump inputs AGAINST the air
pressure set in the positive air chamber.
A negative air pressure setting that is higher than the positive air pressure setting
results in a fork that is more sensitive to small bump inputs.
A negative air pressure setting that is lower than the positive air setting results in a fork that is less sensitive to small bump inputs as well as rider induced fork movement known as “bob”."
HTH
Thanks for the feedback/advice, recommended air pressures are def too high IMO, I'll keep fiddling around and see how I go.
Hi Geoff. I've had a good few pairs os dual air Rockshox now & agree that they need a bit of "Experimentation" before they really start to perform.
Even weighing 84kg & setting accordingly I found the recomended pressures only allowed about 75% movement over all terrain & the fork felt as if the compression/lockout was half on.
I now run less pressure in both chambers & find the fork performs much better.
There's a lot of info regarding more or less negative pressure to be found on various forums so Ill leave that to you to decide.
I personally feel the Reba works best on a hard tail as it's still not a super plush fork but that's my opinion.
The good news is that the fork seems to last well & for its price & weight performs well.
Rgds
T
Finally happy with my fork so thanks for the advice everyone. I've set them up with 110 in the - chamber and 100 in the +. It works really well for me and I'm using the full range of suspension for the first time, it's only taken 12 months. No issues either with it diving in corners so I'm no longer a dual air hater:)
That's good news that you've got it running the way it should be! Enjoy your new (feeling) fork!