I have a weird problem with my Recon Gold solo air forks (29er variant if that matters). They’ve become very firm, and I need to run about 30psi (80kg) in order to get full travel and reasonable sag.

They compress fully when there’s no air in them, so are not limited by the damper, which suggests to me that the negative air chamber isn’t filling properly.

Anyone else had this problem and figured out what was causing it (and found a solution)? I noticed that the solo air spring is different in the Recons (versus e.g. Rebas) and there is no wee Schraeder valve in the bottom of the push rod, just a pin at the top (under the air piston) which can move back and forth.

I am not entirely sure how Rockshox’ own implementation of the older Solo air works; the one licensed by Cannondale (further down the page) relies on the piston moving slightly on the shaft, preloaded by a spring washer.

I’m thinking it should be the same principle, but there doesn’t seem to be enough room for the piston to go further down the shaft, so maybe the equalization happens during rebound/top-out?

@otsdr, thanks for the links, very interesting! I think I did see a small spring under the air piston when I stripped and rebuilt them, so maybe that has worked loose and is preventing the equalisation. I know now to focus on that bit of the fork anyway!

I have the exact same problem with a Recon TK. I haven’t rebuilt mine yet though, it’s stock.
I can’t get more than 60-70mm of travel out of 120, and it’s hard as hell.

This sounds similar to the issue I had with my solo air Reba’s.

Assuming they have the same basic design of air spring …

What happens is you pump into the positive chamber then the pressure equalises through a small dimple on the inside of the fork leg.

The dimple (aka transfer port) can get blocked stopping air pressure equalising. Usually a blob of grease. The port closes off once the fork is sagged as the seal head moves past it and gets a proper seal against the smooth bit of the fork leg.

Or you could have a scratched or damaged air shaft that allows air to flow between positive and negative chambers. This was found to be the cause with my forks and cost a replacement air shaft.

There is a known temporary fix to release the trappes air with a zip tie but I never found it that effective.

At one point the air shaft issue was quite common I believe.

Replacement made mine like a new pair of much better forks.

By the way op I can see you said that the air spring design isn’t the same for recon and Reba but you may want to double check that as the first recon manual I found looks like a very similar design to what is in my Reba’s. At least it does in my tired state reading it on a phone!

There used to be a dual air version of the Reba with two valves and the manuals still come up quite high in Google searches.

If the transfer port is blocked, you might find that pumping up the fork to max pressure and knocking the wheel against the floor could blast it out.

Cool, thanks everyone for the tips. Will give them a go at the weekend!

I had exactly the same issue with a set of solo air Rebas. 3 trips to SRAM / Fishers under warranty never fixed it.

Merlin (where I bought the (from) eventually swapped them for a brand new set and these have worked brilliantly so I can only think that there was some sort of manufacturing fault with the original forks, above and beyond the “port blocked with grease” theorem.

SRAM of course denied all knowledge of any issues with their solo air system.

Older Solo Air and current Recon/XC3x is different than the Solo Air in Reba/SID/Pike et al, the transfer port is more or less in the shaft rather than the stanchion.