Thursday, September 8, 2016

Precious Pressure

I spend a good amount of my time at work worrying about pressure. Specifically blood pressure. I can let pressure that's a bit too high slide for a bit there are usually more problems with pressure that's too low. I think it's the same for bike tires. Too high might decrease traction, but too low will make a bike feel like it's not tracking right. And, if it's too low and you run tubes, you've got a higher risk of getting pinch flats. Too low on a tubeless set up and you can "burp" more air out of the tire and break the seal at the rim/bead. There's a sweet spot for tire (and blood) pressure, and sudden loss of pressure  isn't good in either situation.

I got to ponder this on a recent ride when I got a flat while bombing down a rocky trail. That "psssssssss" sound is distinctive and always unwelcome. I'm running a tubeless set up with Stan's and I got to witness the sealant spewing out all over the trail and my bike in sticky mockery.

Obviously the puncture must have been too big for the sealant to seal, so I wasn't going to just be able to pop some air in via CO2 cartridge and get on with my ride. That's fine, I thought, I'll just pop a tube in.

Ah, that might have been a great trailside fix if it weren't for the fact that the tiny nut on the valve stem, which was tight enough to make a good seal, was also tight enough to prevent me from taking the valve off with my hands. There's not a bike-specific multi-tool out there (that I'm aware of) that has any pliers so I was screwed, and miles from my truck. Fortunately, my buddy Saul rode back, got my truck, and came back to pick me up.

Should have been a simple fix at home, right?

First, my thought was to maybe just add some sealant to the tire, maybe there wasn't enough, or it was too old, to properly seal the hole. It would have been awesome if the valve stem was the type that had a removable core, but alas, that would have been too simple. Popping the tire bead off the rim proved to require a herculean effort. It was like I was trying to pry a 27.5 tire off of a 29'er rim. I broke two tire levers in the process and I wonder what would have happened trailside if I had been able to get the valve stem off of the rim, but I digress. I poured some more sealant in the tire and then forced that bead back over the lip.

Getting that initial seal when inflating a tire can be the hardest part of the tubeless experience, but I had just bought a Topeka JoeBlow Booster which allows you to charge the pump with a liter of air that can then be released in a single burst. Sounds great when you read the marketing copy, but in practice all it seemed to do was push the sealant out around the bead. I pumped and charged and pumped and charged and pumped and charged and never got a seal.

As is often the case, when I have a problem, I throw money at it. Enter new Orange tire sealant (supposed to be better), and new valve stems with removable cores. I also grabbed a different tire from my stash, that to the best of my limited knowledge, didn't have any major damage.

Back to the ridiculous amount of effort to get the tire off (and the new one on). Replace the valve stem, and get out the booster pump. That tire actually had a hole in the sidewall, more sealant spewed all over the garage, and I finally gave up.

I've never had all this drama with tubes. If I had been running tubes, I would have swapped out the tube during that ride and continued with only a few minutes of down time. And, there's about two hours of workshop time that could have been spent riding or watching cat videos, or my latest addiction, Ozzy Man Reviews.

Anyway, I'll probably go back to giving tubeless a try again, but I need some time away from the sealants and pumps.

This was all making my blood pressure go up...


FCMan said...

Buy a cheap compressor, ridiculous but worth it. Also Michelin 29 in tires are insanely hard to mount. I bring them to Beverly Cycles and worry about trailside repairs!!!

FCMan said...

Buy a cheap compressor, ridiculous but worth it. Also Michelin 29 in tires are insanely hard to mount. I bring them to Beverly Cycles and worry about trailside repairs!!!