Air Goes On The Inside

And it would be nice if it stayed on the inside. But sometimes things don't work out the way we'd like them to, as is the case with the rear wheel on The Stig.

After a lovely first ride, I hosed the dust off the bike and left it out in the sun to drip dry. When I came back a few hours later, I found the bike mostly dry, but also sitting a little low in the rear; the tire having gone completely flat.

A bit of examination revealed no issues with the tire itself, or the seal of the bead on the rim. That left only two possibilities: either the air was getting under the rim tape and leaking out a spoke hole, or it was leaking out around the valve stem.

I pulled the tire off to have a look, and the rim tape itself didn't seem to be showing any major issues. When I removed the valve stem though, I observed that the valve stem was wet with sealant, and that the rim tape around the valve stem hole was curiously puckered and uneven.

The rim tape had also been applied in a way such that the edge of the tape intersected with the edge of the valve stem hole, and that certainly wasn't helping things any.

Lacking any better options, I pulled off the rim tape to get to the source of the unevenness that I felt around the valve stem hole, and discovered that some parting line flash had not been smoothed down in this area.

Anywhere else on the wheel this wouldn't be a huge issue, as the rim tape would just lay over top of it without issue, but here at the valve stem it was making the edge of the valve stem hole uneven and possibly contributing to a poor seal.

Thankfully it wasn't too difficult to buff it down flat with a needle file, followed up with a bit of fine grit sandpaper to remove any scratches.

Another contributing factor was the design of the valve stem itself. The ones that came from the factory use a conical wedge shaped plug to seal against the valve stem hole.

This works fine on a mountain bike rim, where there's plenty of room in the center channel for the wedge to seat down into the hole, but on a narrower road or gravel rim things don't quite work out so smoothly compared with the alternate hotdog-bun-shaped plug.

The good news is I had a pair of the latter on hand, so I swapped one in on the front (pictured above) and then ordered up some new rim tape for the rear.

Sadly Amazon hasn't invented package teleportation, yet, so I had to wait until Sunday for the rim tape to arrive. But, arrive it did.

I cleaned the rim squeaky-clean with some alcohol and lint-free wipes and then set about stretching the new tape into place.

#NotSponsored.

The new tape and valve seemed to do their job holding the air on the inside instead of letting it squirt out to the outside, so here's hoping that trend keeps up.

It kinda sucks that I couldn't go for a longer ride this weekend thanks to this issue, but there's always next weekend.