13 July 2008

bikefix Midterm Review: RockShox Revelation 426 Air U-Turn

"Is exactly what it says on the tin." Sure, calling your suspension fork a "Revelation" requires a fair bit of hubris, but it seems that SRAM's Rock Shox is pretty darn close to the mark on this one. Released a few years back, the Revelation is Rock Shox's entry in the increasingly competitive 'trail' fork category. What this translates to in numbers is a 4lb, 100-130mm travel fork with stiff 32mm stantions. Up against forks from Fox (TALAS, Float, 32 VAN), Marzocchi (XC 700, 44), Magura (Laurin, Menja) and Manitou (Minute), it would seem that Rock Shox doesn't have much of a chance. This is a shame, because of the 5 or 6 forks in this category that I've owned, the Revelation certainly has the best mix of ride and features.

When I ordered the Revelation last October, I was replacing a temperamental Marzocchi XC700sl (which undergoing rehab at the company's warranty department). That had replaced a pimp, (self-adjusting) Pace RC40 Fighter which had in turn replaced the popular (but hardly excellent) Fox 32 TALAS. Before that? I'm not sure, but a Maverick DUC 32 and 2004 Fox TALAS are back there somewhere. Why so many forks? Well, there are a number of reasons. First, I'm a light guy. At 145lb, a fork has to have exceptional small-bump sensitivity to work for me. Otherwise, seal and damper stiction can make a fork feel very harsh on the small stuff. Because I'm not in the middle of most forks' adjustment ranges, their air springs aren't at pressures where they ramp up (become progressive), so bottoming out can be a problem. My Maverick, which works extremely well on both small and large bumps tends to highlight forks' small-bump harshness and the bike's somewhat rearward weight bias certainly doesn't help either. So, what is it about the Revelation that has kept it on my bike for 8 months (with no plans of my part for a change)?

Here's what I think it boils down to: two adjustable air springs. The Revelation 426 Air U-Turn has both adjustable positive and negative air springs. The main spring is a large-volume affair, pressurized from the top of the left leg. The negative spring is a much smaller chamber that is pressurized at the bottom of the same leg. The two springs push against one another and reach an equilibrium (ideally at the top of travel). Think about a spring pushing a weight against a hard surface. It takes a bit to get it to move against the spring, doesn't it? Now, picture the same weight suspended between two opposed springs. You can imagine that it would move much more freely than the first weight, right? Being adjustable, the negative spring can allow the rider to run more air pressure (for a more progressive feel) yet balance that with a higher negative spring pressure, which maintains small bump sensitivity. Want a more linear feel? Less positive pressure, less negative pressure. Want to feel all race-y (not recommended)? More positive pressure, less negative. Beyond that, the Revelation's compression damping is on the light side and the rebound damping is externally adjustable.

So, what we have is a very tunable, active fork- which won't be for everyone. However, I'm of the option that, if I'm going to spend $663 on a fork and carry it around, it ought to be working for me all of the time. That means not only taking hits on the descents, but also improving traction and reducing the need to lift the front wheel while climbing. RockShox have included in the "Push Loc, Air U-Turn" version a very slick (think clicky pen) handlebar-mounted remote lockout (which I very rarely use), an external compression damping adjuster (which effects how locked out the lockout is when engaged), and a simple travel-adjustment knob.

Essentially a very nicely machined wingnut (which folds flat), The Revelation's travel adjuster it isn't as slick as Fox's 3-position travel adjuster but works just fine. I find myself going back and forth between 115mm (4 half-turns in) and 130mm fairly often, and the big ol' adjuster is particularly suited to gloved or numb fingers- much easier to grip than Fox's, Marzocchi's, or Pace's. Sure, it could be quicker (or even better- bar mounted, rather than the lockout), but given that it's been simple and trouble-free, I'd hesitate to change things. For really steep, long climbs, I do drop the front end to 100mm, but that's the exception rather than the rule. The travel scale printed on the stantions is a nice touch, one which others would do well to copy.

If you're not a fan of active forks, the Revelation Air U-Turn probably isn't for you. When hammering out of the saddle, it can move- a lot. Good riding form will of course help to prevent this, but it's going to move. When climbing, the fork seems to at its best when left unlocked. Even at slow speeds, it absorbs most bumps well, reducing the need to manually lift the front wheel. Sit & spin is generally the way to get to the top and flailing around isn't rewarded one bit. Pointed downhill? This thing is unreal. It feels almost like a coil spring- one that doesn't blow through the last 2/3 of its travel. Folks who hop on my bike regularly comment on just how plush and predictable the fork feels. High speed or low, big hits or braking bumps, it handles them all very well. Unlike the TALAS, which would occasionally feel overwhelmed in rock gardens or over stutter bumps, the Revelation has light enough rebound damping that it recovers after every hit and the negative spring helps to prevent any topping out.

After 8 months, this fork is showing no visible signs of wear. The paint is of a very high quality (which is becoming increasingly rare) and the stantions look new. I think that the outer seals (wipers) are starting to wear a bit, as there's a bit of a breathing sound starting to come from the legs (especially on wet rides), but that's not the end of the world. If it's at all like the Reba, it's a doodle to pull apart and the wipers and foam rings are easy to come by. There's a very slight clunking sound at the top of travel, but that's been there all along and can't be felt through the handlebars- it could be annoying, but it doesn't really bother me. The IS caliper mounts are a bit annoying for those of us who like 180mm rotors, but most brakes and rotor kits do come with the appropriate IS adapters. I believe that the disc-only casting is shared with the less expensive Rock Shox Tora, which either means that the Revelation has cheaper/heavier lowers than you'd expect or the Tora gets nicer legs than it should. Reality, I'm sure, is somewhere between the two.

If I had it to do again, I'd be tempted to go without the remote lockout. It's nice and all, but my bars are getting crowded and I just don't use it that much. Going without means an extra $60 in your pocket and a white (rather than black) fork. If you're good with a fixed 130 or 115mm of travel, the non-travel adjustable version is only $510 and weighs 3.75lb- which is not only light but reasonably priced. All in all, though, I've been thrilled with the Revelation. It's proven not only to be reliable, but a great match for fully active "Trail" bikes. It would be a good match for the Pivot Mach 5 that we tested this spring and the 140mm 2009 version would suit the Commencal Meta 5.5 well too. For all-day backcountry rides (like this week's 9hr suffer-fest), I haven't found another fork that I would rather ride.




Carl Martens said...

Well written review.

SeeAPennyPickItUp said...

Thanks for the writeup. I just got the less expensive 409. I understand others have had issue with it, Ill give it a try. Ive only ever owned 68 and 80mm forks so Im looking forward to something with alot more travel!

bikefix said...

Penny- Thanks! We've recommended these forks to several people and so far, so good. If it doesn't turn your bike into a chopper, I'm sure you'll love it.


Alex Todoran said...

Just came home from the store, with the 409 2008 Revelation with U-turn. Of course I tilted the fork, up and down because it was not installed on my bike yet. I noticed a leak of oil around the internal floodgate, not much but it's there. Should I be concerned? Is it because of the tilting? Will it stop in the right position?

bikefix said...


If what you're seeing is just dampness (weeping), I wouldn't worry at all. If there's enough for drops to form, back to the shop it should go (where it'll be under warranty with your receipt). Good luck!