SRAM Reverb Stealth B1
The Reverb post is simply a given. It's one of those products I ride many times a year but don't ever think about reviewing because it's been around forever. While the Reverb has one of the best rebuild manuals on the market, there are a couple other important techniques and suggestions Jeff will demonstrate here.
This is a brand new Reverb B1 Stealth with the new shifter-style remote and the Connectamajig. It's a one to two beer, or case of beer and trip to the bike shop the next morning rebuild, depending on mechanical aptitude and experience.
The two key features of the Reverb B1 series compared to past Reverbs are the newer generation seal on the internal floating piston (IFP) replacing the previous o-ring, (which does an excellent job of preventing any air/oil bypass under pressure) and the Connectamajig.
Connectamajig allows the Stealth post to be removed without having to re-bleed the actuator line. In this case, because the post was brand new, it meant we could rebuild and re-bleed the Reverb without having to do anything more with the remote and line than detach and reattach it.
The Connectamjig hose coupler is not a new idea. Similar systems are used for many industrial and heavy equipment applications but it's a great example of looking beyond bikes for ideas that make service faster and easier. Another example of SRAM making service easier on hydraulic products is their quick connect bleed fitting.
The newer Reverbs also have an inverted seal position which prevents oil from escaping when assembling the post. It's much less frustrating than the old posts. If you've tackled a rebuild in years past and it didn't go well, definitely consider giving it another shot.
Oh, and please at the bare minimum get some aluminum soft jaws for your vice. Aluminum shaft clamps are the best option if you're going to be working on your own suspension a lot. Scratching anodized sealing surfaces gets f***ing expensive and it's not covered by warranty when you beaver the sh*t out of aluminum internals.
SRAM does a great job of making specific tooling available to service their products. With all the Reverbs out there a shop doing service can easily recoup the cost of doing this right. Shops and tool nerds doing a lot of RockShox service will also likely be drawn to the SRAM & Abbey Tool collaboration tools.
Bleed fittings aside, anyone who isn't rebuilding posts in a time-equals-money situation can do this rebuild with some Knipex pliers and carefully chosen, smooth, cylindrical objects. I've always believe best practices vary depending on whether I'm working on my own stuff or a customer's.
Free The IFP
As part of our Race Face Aeffect dropper post teardown Jeff demonstrated the zip-tie trick for removing an IFP. His preference for the Reverb is actually to create some back pressure with his thumb and pump it out.
The new B1 Reverbs have an excellent reputation for reliability but still carry the weight of the product's early reputation. It's easy to forget that the Reverb was the first widely accepted dropper post on the market and has survived in the same basic form through complete redesigns by all of its early competitors.
The Stealth routing is an obvious change but otherwise the biggest difference is the new IFP which replaced a simple o-ring with a large high pressure seal which flares under pressure. This seal prevents the air/oil bypass that created spongy posts, caused failures in the cold and a cost of ownership that was too high with the past models. A new IFP will require a break-in period, even with a good lubing.
If you're going to strip down a Reverb, clean it and then rebuild it, please change the seals at the same time. Relative to the rest of the effort, it's a small cost.
On any product where seals are being removed and replaced Jeff recommends stabbing the seals themselves with the removal pick. This destroys the seals but should prevent any scratches to air cans or other anodized surfaces.
Reinstalling the IFP is a straightforward task. Grease the IFP, press it in to the required height and then fill the upper tube with oil. As with any hydraulic system, patience is the name of the game. As Jeff says, "bubbles are dicks", and if there's remaining air there's a good chance the post will be spongy no matter how the rest of the rebuild goes.
There seems to be a lot of confusion about how the hydraulic remote on a Reverb works. Like many cable actuated dropper posts, the fluid in the remote is simply depressing a poppet valve which in turn opens the (blue) piston assembly in the inner shaft and allows fluid to travel. Along with the rider's weight depressing the saddle, this causes the post to compress until the rider releases the remote which closes the system and locks the post in place. Push the remote without the rider's weight on the saddle and air pressure acting on the IFP causes the post to extend.
The hydraulic system that is the remote, hose and poppet assembly is bled separately from the post itself. Bleeding the remote won't solve issues with the post being spongy and likewise rebuilding the post won't solve issues with air in the remote system.
Before the poppet valve assembly is installed it's important to set the oil height inside the inner tube. SRAM makes a handy tool for removing fluid from the inner shaft but I've seen quite a few do-it-yourself versions that seem to work fine for anyone who wants to bypass the 45 USD cost of the tool.
As with a lot of the teardowns with Jeff or with James at SuspensionWerx, the name of the game here is Slickoleum, or in this case SRAM Butter which is the exact same stuff. Brass key ways, seals, o-rings, the outer post tube, the bottom out bumper and definitely every facet of the IFP. Go to town.
There are two assembly steps that folks seem to regularly screw up. The first is forgetting to install the seal head onto the upper tube before sliding on the outer tube and tightening everything together. Nothing like having to tear the post back down because the seal head assembly is still sitting on the bench. The second issue is to not allow the inner shaft to compress when installing the poppet valve. This changes the IFP depth and requires the post to be fully disassembled again.
Because Jeff knows the fluid in this brand new post is good and since it functioned perfectly before undoing the Connectamajig, he just bled the poppet valve cover itself to be sure that when the line is reattached there is no air in the system. Around Bikeroom this is called 'The Egor Method' since it was one of Jeff's assistants that suggested it. It's a great application of one of my favourite Tao 'don't fix what ain't broke.' Unless of course it is due for a service.
Air in the remote system will result in a spongy feeling at the remote since the air can compress when trying to depress the poppet valve. In most cases, the post will still hold solidly at the chosen travel point even if the remote is spongy.
On the other hand, if the remote feels solid but the post doesn't hold solidly in position (sags or telescopes) that is a sign that the post itself has an air bypass issue and bleeding the remote won't help.
Ride & Repeat
It's highly recommend by most mechanics I know that riders remove the seal head and re-lube the upper tube every 50 hrs of riding or so. This can be accomplished without removing the post from a bike and is a three-minute job at most. SRAM also recommends removing the lower post body and cleaning, inspecting and re-lubing the key ways at the same time so I'll call that best practices while recognizing it's a lot more work. The full rebuild service is recommended every 200 hrs of riding which is about two years' worth for most riders. For anyone getting after it with one bike I'll call that a yearly service. Best practice is to replace the brass key ways at that point.
More shops are recognizing that service is an increasingly important aspect of a healthy bottom line. In the past many places shipped out Reverbs for a rebuild but most now handle it in-house, slashing down time for customers and adding service revenue.
The little post that could. It's impressive how little the Reverb has changed in almost a decade since it was released and also how much more reliable and easily serviced they are today.
Kudos to SRAM for supplying detailed rebuild manuals for their products that are easy to locate for shops and home wrenches. Manuals like the one for Reverbs give the do-it-yourself-er an honest shot at pulling off a good service without damaging their product or voiding their warranty. Consider giving it a go.