February 15, 2019 at 03:38 #256873
I’m back on an MTB after a 20-year period of road cycling. Just bought a new XC hardtail with a 2019 Rockshox Reba RL (100mm, 29 inch, Boost)(https://www.decathlon.fr/vtt-xc-500-29-12v-id_8518393.html).
So far, I run with 10% sag, no token, and fully-open rebound, Which works fine for me. But I can’t tune the compression damper on the Reba RL the way I want to.
Not locked-out, I’d like to be able to increase the compression damping ‘a bit’.
Locked-out, I’d like to increase massively the compression damping, or even achieve a real lock-out of the damper (which the stock Reba RL doesn’t provide). Locked-out, the compression damping only increases marginally. The most notable difference the lock-out makes is increase the damper noise as the oil passes through the damper (‘squishy’ noise of the oil bubbling through the damper holes)
Any recommendation to achieve those goals of increased damping? Maybe change the compression damper unit? or change the complete damper unit (compression and rebound) with a Charger-like unit designed for a SID fork (if compatible with the Reba)? Plug 1 of the 2 drillings in the compression damper piston? Maybe run a higher viscosity oil in the damper (which hopefully won’t slow down too much the rebound)? Any other suggestions…
Thanks for your help
February 15, 2019 at 07:28 #256877
It sounds to me that your damper is faulty – the “L” in “RL” designates that it should be a full lockout, rather than a slight tweak on the low speed compression as the “RC” on other forks would designate. I certainly wouldn’t go drilling holes in the damper. Return it to Decathlon for a warranty repair/replacement.
February 15, 2019 at 15:16 #256897
Thanks Sam for your feedback.
I actually got a first bike delivered by Decathlon a few weeks ago. I thought the Lock-out was faulty, and got the bike exchanged (BTW, the Decathlon customer service was great and very easy to deal with to organise the swap).
A week later, I received a new bike. And the behaviour of the compression damper was exactly the same. I drove to my local Decathlon shop, and ‘pushed’ on the RockShox Reba RL they had in their inventory on similar bikes. Turns out, that none of the Reba RLs actually fully lock-up. They all felt ‘squishy’ when locked-out. And they all felt pretty inconsistent. That’s why I’m thinking of updating/hacking the compression damper myself.
I pulled out the compression damper out of my fork. Everything looks normal. In the unlocked position, the 2 holes in the compression damper line up (between the aluminium and the plastic part). In the spring-loaded locked position, the holes don’t line-up. The o-ring on the outside of the daper seems to seal well againt the fork leg.
My guess is that the leak between the aluminium and the plastic parts (the ones with the calibrated holes) is so large that the control of the oil flow is poor. I guess that more oil leaks between those 2 parts than through the 2 holes.
The rest of the fork works reasonnably well. And the fork is pleasantly rigid (especially compared to simalarly-priced Fox forks). So, I’m inclined to change the damper (either the compression damper, or the complete compression/rebound unit) for a higher spec model. But I don’t know which model will fit? Charger? Charger 2? Are they available for 29″ 100mm Rebas? and especially, which damper models actually offer a ‘real’ lock-out?
February 15, 2019 at 15:39 #256898
Huh, interesting. Previous versions of the Motion Control damper have had a full lockout. Interesting. Anyway.
First thing to do would be to try a heavier weight oil. Obviously that will change your damping throughout the whole range, including fully open. But this is the cheapest/least destructive thing to do.
As for the charger damper, I don’t think there’s one available for 32mm stanchion forks. That said, I’ve been wrong before.
EDIT: yes I was wrong, the SID uses a charger. It’s not really a full lockout either, but the damping is vastly improved and is much better controlled, definitely a good upgrade if you’re thinking of doing it.
February 17, 2019 at 03:05 #256920
Thanks Sam, I’ve found a hack that makes the Reba RL works (ish): No impact on the ‘open’ compression damping, but at least the lock-up works as intended (almost fully locks-up after 3/4mm of travel).
I replaced the spring at the bottom of the compression damper assembly with a much stiffer spring (not quite the right dimensions, but it works). It’s the spring that maintain the blue-anodised valve closed during compression and open during rebound.
Compression damper assembly
Valve in open position (during rebound)
After a ride, the modification seems to works consistently. I’ll see over time if I try with a higher viscosity oil, but I’m concerned it would slow down too much the rebound damper.
For now, this will do the trick. I wish someone at Rockshox will read this post and apply the modification to the gazillion different versions of the Reba RLs, or at least offer a replacement spring for their exiting customers.
July 24, 2019 at 10:31 #266642
I’m giving up on the Rockshow Reba. The Motion Control damper is too unreliable for me. Over the past 5 months, I’ve spent 90% of the time with a non-functionning lock-out, and a changing level of compression damping.
My understanding is that the blue-anodised release valve on the compression damper has so much play that it rarely seats properly against the damper body.
After test-riding a bike with a Fox 32 fork, I’m not convinced either. The spring and damper felt much better than on the Reba, but I was massively disapointed by the super-flexy chassis.
So, I’ve decided to upgrade my bike to a rigid fork. I’m therfore looking for a rigid fork: approx. 480mm axle to crown, 51mm offset, 110mm boost spacing, aluminium or carbon, ideally compatible with 200mm rotors, clearance for 700x55c tyres, and the whole thing for a reasonable price, of course?
A bikepacking.com article lists quite a few options (https://bikepacking.com/index/forks-with-bottle-cage-mounts/), but nother under USD 500… I’m looking for a more cost-effective option. I’m happy to go with an aluminium fork. I’ll save close to a kilogram compared to the Reba RL, so I’m not to fussed about 50 or 100 additional grams of an Al-alloy fork.
July 24, 2019 at 11:30 #266646
My rigid has a steel fork on an aluminum frame. There may be something to that to be a little more forgiving. This Salsa fork pretty much fits the bill except it is steel and non-boost. Perhaps a little more digging you can find a boost version.
July 25, 2019 at 03:51 #266693
Thanks Vapidoscar for the pointer.
I spent last night geeking out on lots of component websites, and came to the realisation that it will be more cost-effective to buy a new bike rather than upgrade my RockRider XC 500
I bought the bike earlier this year. In approx 6 month, it’s completed 3,000 km and about 100,000m+, and I have to accept that it’s reached its end of life. It’s been a good bike, and got me through Navad 1,000 in less than 7 days. But Navad has tested the components to their limit:
- the rear wheel is taco’ed (I broke 2 spokes during the race, rode the last 200km of the race with the broken spokes. I fixed the spokes once home, but on further inspection, the rim is taco’ed beyond repair)
- The 32 and 36 tooth cogs of NX cassette are worn out (and require replacing the complete cassette)
- the GX rear derailleur still shifts OK-ish with a newly-fitted cable, but the cage has a lot of play
- the Rockshox Reba RL… see above. And I’m switching to a rigid fork anyway: 1kg saved on the bike and the added robustness (the compression damper on my Reba gave up working after 500km of race) will outweigh the few seconds lost on the descents
- The Rockrider 500xc 29″ is fitted with SRAM Level T (180 front, 160 back). The Navad 1,000 route included 5 or 6 long descents (over 1,500m-). I clearly noticed a decrease in brake performance as I progressed in the descents, I suspect linked to the pads and discs warming up. Typically, after 500m-, I’d have to switch from 1-finger to 2-finger braking. And after 1,000m-, I got strong reminders of my cantilever brakes from previous bikes… More alarmingly, and even on the shorter descents, once every 20 or so braking, one of the brakes would fail to provide any kind of power. The lever would feel very spongy, and provide virtually no braking power. Then, the power would could back after a few minutes just as randomly as it disappeared. Anyway, my conclusion is to switch to 200mm rotor front and back, and Shimano 4-pot calipers (Saint or XT 8120). I had heard that SRAM brakes were hopeless (both local bike shops around me rent MTBs and sale them at the end of the season, and both shops told me that they’ve given up on SRAM brakes because they don’t survive a 3-month season on rental bikes), now I can confirm based on my own experience that I won’t run again any SRAM brakes
So overall, that’s a lot of money to spend on a bike: changing the rear wheel is the chance to switch to Shimano MicroSpline and run away from SRAM… but the math adds up to a too big total. Rear wheel with MicroSpline hub (EUR 400), SLX cassette+shifter+derailleur (EUR 300), XT brake set +discs (EUR 400), ridig fork (EUR 500)… and the total already exceed the value of the bike when new.
So I guess I have to accept that the bike has serve me well so far, but I will upgrade the whole bike. The Orbea Alma M15 is indeed very tempting: it’s SRAM-free, and can be fittedd with Orbea’s Spirit rigid forks. I’ll geek out for a couple more days on OEM’s websites, reading through specs and geometries… but the Orbea Alma seems pretty much spot on for me.
September 3, 2019 at 09:48 #269384
Bumping this conversation related to recent podcast: https://www.singletracks.com/blog/mtb-podcast/listen-buying-a-mountain-bike-then-racing-it-1000km-across-switzerland/
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