Reverb B1 (non-stealth) – dropping under load, and fixing it.

This is a slightly unusual singletrackworld post, in that I had a problem and found a way to fix it. I thought I’d share my experience to spread the knowledge, and maybe it will help someone out.

So – I have a Reverb B1 non-stealth, bought new around 3 years ago. I love it, had no issues, and have only ever done one 50-hour service.

Recently, it started dropping a bit when I sat on it, especially at full height. Maybe 5mm – not much, but enough to annoy me. The internet told me I needed to do a full, 400-hour service, as it had air under the poppet valve (it also said I could possibly get away with just removing the poppet valve and refilling the oil, but it was about time it had a service anyway). I did once pick the bike up by the seat when the post was down, and at the time I felt like I had done something wrong. This may have been the cause, as it can force air past the seals. In fact, when I rented a bike at BPW, the only thing they told me was not to pick it up by the seat.

Here is what I learned:

1. The folks at TF Tuned are awesome, and will happily share their valuable knowledge and experience.
2. The 400 hour Reverb service kit contains all the parts of the 200 hour kit, so you don’t need to buy both.
3. The 400 hour kit doesn’t contain all the right o-rings for this seatpost – I wasted a lot of time with the poppet valve after fitting the new o-rings, only to work out that they were a different size. After taking advice, I re-fitted the old ones.
5. Yes, it is possible for a home mechanic to do the 400 hour service, if you value money more than time, or just really want to do it. If you are only mildly patient and slightly butterfingered, it will be more of a PITA. It took me around 6 1 hour-ish sessions in the garage to get this done (I have an 18 month old, so my time is very limited). I could now do this again quicker, but that’s not very useful to me as I hope not to do it again for ages (on the upside, almost any other job on a bike will now seem a lot easier, including the 200 hour Reverb service).
6. You do need almost all of the recommended tools. Soft jaws and large wrenches are a must, along with a seal pick. I decided I could make do without a few of the others, but this also cost me a lot of time. There is no substitute for the post bleed tool. I thought I could find something to push the IFP down, but it was surprisingly tricky. It needs to be a very specific diameter, of a softer material than the post, and not so thin it just pushes out all the grease in the IFP. I ended up 3D printing a part, which brought its own issues (mostly dimensional accuracy and shrinkage) – the final item was 20.5mm OD and 15.3mm ID, and just about did the job. I made do without the oil height tool – at that point, I just put the post bleed tool back in a few times, and that seems to have set the oil at about the right height.
7. I was pre-warned about the release of pressure when removing the poppet valve. As it has pressurised air behind it (which is the cause of the post dropping), it can come out with some force. I kept a rag over the top when removing the circlip, and it went ok.
8. When the instructions say “keep hold of the post bleed tool otherwise you will have to take it all back apart”, keep hold of the dang bleed tool!
9. This all might be a bit premature, as I have only bench tested it now it’s back together. Now for the worst part of fixing anything – waiting for it to break again.
10. Good luck.

Congratulations on having the courage to tackle it.

Not so bad once you’ve done it, is it?

One thing I really like about the Reverbs is that they’re completely rebuildable and repairable and all the parts are available.

 I thought I could find something to push the IFP down, but it was surprisingly tricky. It needs to be a very specific diameter, of a softer material than the post, and not so thin it just pushes out all the grease in the IFP.

20mm electrical conduit works well – £1.70 for 3 metres (!) at Screwfix

It isn’t so bad now it’s all over, it was a right hassle at the time though. I did buy the Reverb largely because it is theoretically re-buildable at home (it’s also why I have Pike and Lyric forks, and not Fox). Thanks for the conduit trick – will do that next time.

I just did the same due to the same issue.

I read the issue is air getting past the IFP. with that reasoning I thought i’d have a go at seeing if just taking it apart and reassembling would work. And it has.

The pdf guide isn’t as scary as it looks once you start working through. didn’t replace any seals and left the poppet assemblies alone

I used no special tools: https://singletrackworld.com/forum/topic/ghetto-reverb-full-service-kit-bodgetastic/

for the vice I used a rubber golf club shaft holder I had from replacing the air shaft on my pikes.

I poked the ifp down with a lollipop stick. didn’t think about the grease but it mixes with the oil so wont last there.

rebuilt and bled, all working.

@joefm Fair enough, if that worked. I followed the manual, and the poppet valve removal is after all the rest of the post has been taken apart. There was still a lot of trapped pressure and frothy oil when I took it out, so I think atleast some of the problem is inside the valve itself. All done now anyway.

Also, if you’ve got the sagging issue but you don’t feel it needs a full service, you can just go through the steps and bleed it but not replace any parts. It’s a pain in the arse but it does the job.

That said, last time i just said screw it and sent it to these guys:
https://www.ebay.co.uk/itm/ROCK-SHOX-REVERB-SEAT-POST-SERVICE-BY-EXPRESS-RETURN-We-are-staying-open/274316522619?hash=item3fde89f47b:g:gtcAAOSw3v5Ytrm6
They serviced it and also replaced my seatclamp for free as it was a bit damaged.

I find the videos on YouTube really helpful. I’ve got a firesticked tv in the cellar, so watch a bit, pause it (control in freezer bag to keep it clean) then do that bit and so on. Same with the fork services.