In July 2014 we introduced our 90-degree air chuck for the CyclePump, the EZAir Gauge, and for the Clip-On version.  We invented it for bikes that have limited clearance between the valve stem and the hub – where a straight air chuck simply won’t fit.

Since then we’ve sold thousands of those 90-degree chucks, and they made our customers pretty happy… except for a few who reported the chuck could cantilever a few degrees when attached to the stem, and that could cause a leaky air seal.  Almost all of those complaints were from BMW riders who had TPMS valve stems.

We scratched our head about this issue, so we bought some BMW TPMS stems for an engineering study.  What we found surprised us: those BMW stems are rather odd.  The threads were unusually short and the main body of the stem is larger than the threads.  We tested and compared them to other stems, and confirmed the fact that the design of the BMW stems could make it harder to get a good seal.  Sometimes it worked, sometimes it didn’t.  There was no quick fix, all we could do was to tell customers to keep trying until they got it right.

We came up with several prototypes designed specifically for those BMW stems, but the costs of production prevented us from bringing them to market.  We needed a 90-degree chuck that would fit all known stems, not just one brand.  It had to be affordable, and it had integrate into our current design.

Sometimes the solution to a problem like this can be a simple thing – and in this case it was.  We found if we fitted a spacing O-ring on the chuck, it allowed the tire valve stem to go deeper into the socket of the air chuck, and that depth prevented the chuck from twisting on the stem.  We also discovered that the O-ring spacer reduced the amount of compression needed to seal the valve stem against the internal O-ring (the one that surrounds the nipple in the center).

Testing proved the concept worked; a good airtight seal was made with those BMW TPMS stems (and other brands of stems).  We’ve now implemented this new design on all of our 90-degree air chucks (CyclePump, EZAir Gauge, and the Clip-On Valve Stem.

So… what about the customers who have an earlier design, the one without the spacing O-ring?  This new design isn’t a warranty issue, instead it’s a product improvement and upgrade. We won’t recall earlier 90-degree chucks, but we will send you a free O-ring and you can do the upgrade and installation yourself. 

All you have to do is send us a SASE (Self-Addressed-Stamped-Envelope), and we’ll mail one to you.  Our address is on the home page of our website.

Installation takes about 5 minutes, and it doesn’t require any special tools.  The attached PDF file shows you how it works.  If you’re all thumbs, we can do the work, but you’ll pay a fee (read the sheet).

Upgrade 90-degree chuck with an o-ring spacer