Reba Solo Air negative chamber suck

larkim

Just posting this as some of the other posts on the same subject I thought were a little unclear. Could be me, in which case ignore this post, but hopefully it will come up as a google search for someone sometime and be of use!

Son reported that his Rebas were showing less and less travel, and when I came to look only 80mm of stantion was exposed even when the front wheel was unloaded (e.g. in workstand).

I read about the negative chamber getting over-pressurised potentially causing this, so diagnosed this as the issue needing addressing.

I released all the pressure from the normal valve on the top of the left hand fork (he'd put way too much pressure in anyway), and promptly the fork was sucked down so that zero stantion was exposed. Pulling on the wheel wouldn't expose any more.

Having read about some small oil releases when solving this, I removed the wheel so that the disc wouldn't be contaminated.

Then with a 5mm allen key undid the black bolt in the bottom of the left hand fork. Initially I was expecting this to release some pressure (wrongly). I then removed the bolt completely and looked up inside. I could then see the tell-tale sign of the pin in the middle of a valve (as with a schrader valve). I used a small torx screwdriver to reach inside and depress the valve pin and (stupidly) got a small spray of oil in my face for my sins and fully depressurised this chamber.

Instantly the fork lowers were released from being sucked down. Put the bolt back in, wheel on, pumped up the fork as normal to the recommended pressure and the full 120mm of travel was restored.

The bit I hadn't gleaned properly from other posts on this same issue (which I suspect carries over to other Solo Air forks too) was that I needed to remove the bolt completely to unhide the valve. I'd also note that it is a reasonably long reach inside the fork to get to the valve, so a normal allen key is unlikely to reach.

Hope this helps someone at some point.

There may be another underlying reason why this negative pressure chamber got over-pressurised, but we'll run the fork for a few weeks and see if it re-occurs. If it does, then a service is on the cards.

rockmonkeysc

What year and model Reba are they?
If they're dual air you'll probably need to do an air chamber service and will need a service kit with new o rings.

JGTR

There is an air bypass port that can get blocked, it's a tiny groove in the side of the air chamber that allows the upper and lower air chambers to equalise.

The Rookie

The fact it has a lower Schraeder valve suggests its dual not single.

JGTR

The Rookie wrote:

The fact it has a lower Schraeder valve suggests its dual not single.

Soloair Rebas also have a lower a schrader valve, you are only supposed to use the top valve hence the lower one is hidden right up inside the leg.

rockmonkeysc

My solo air Reba only had the top air valve. They wouldn't need two air valves.

Dirtydog11

Some Rockshox solo air forks do have a valve on the bottom, it's there to release any pressure build up/pressure drop in the lowers.

OPs had developed a vacuum and the reason they re-extended when the valve was depressed.

There are effectively three air chambers in your forks, the positive, the negative, and the lowers. Positive and negative should be balanced whilst the lowers (when fully extended) should always be at atmospheric, Fox did something similar on their 40s.

Can't explain the vacuum though, would be thinking about fitting an air service kit if it returns.

JGTR

I think the later Rebas only have 1 schrader valve. Mine was 2013 which has 2 and is Soloair.

A quicker way of releasing pressure in the lowers is to insert a cable tie to break the fork seal I believe

larkim

The clue is in the thread title. They are solo air Reba's, late 2014 forks (came supplied on a bike bought Jan 2015).

The lower Schrader valve is hidden as I've described. It's not for inflation, seems to be just for releasing pressure from the negative chamber. Inserting a cable tie past the seals at the top sounds more likely to cause seal damage compared to the process described above.