April 2: Tubeless tyres

I’m pretty motivated to not repeat what happened in Belgium. So this weekend I ordered all the remaining things I needed for my repair kit, and arranged some time to set up the tubeless tyres. It's a rest week: all that's on the schedule is a two hour ride… so if there's tyre problems I have until 10pm Sunday night to get them fixed.

Tubeless tyres can be very reliable: but there’s a lot to learn when getting started, they need regular attention, and will leak noxious chemicals if mistreated.

In comparison innertube tyres won't make nasty messes, happily survive constant neglect, and when there's problems you knot them up, bin them and get another.

Much like an actual dog, compared to a stuffed toy.

But let’s back up a bit. Tubeless tyres have no innertube: the tyre itself is pressurized. This means that the join between the edge of the tyre and the rim has to be airtight. And the rim itself also has to be airtight: so the spoke holes need to be closed up. And all those airtight joins have stay airtight even under pressure - like, the pressure of a fully loaded tour bike hitting a monster pothole at 40kph. So there’s a lot of ways for them to leak, without even considering punctures.

The solution is tyre sealant. It’s a latex-based magic gunk, you pour 60-90mL into the tyre and when there’s a puncture or leak it dries and hardens and seals it. So small punctures self-seal so fast you might not even notice. Larger holes might need a bit of help: there’s thing called “bacon strips” (official name: tubeless tyre plugs) which get jammed in and provide a bit of structure for the sealant to harden around. It’s good practice to have a needle and thread; in the event the tyre gets slashed open you can suture it back together, top up the sealant, and with a bit of luck it’ll hold pressure.

They are genuinely much more reliable than innertubes … if set up properly.

And that setup is a bit like toilet-training a puppy. Better get it right or there’s going to be misery.

My rims are “tubeless ready” which meant they have the spokes properly sealed up and rim tape professionally applied. Unfortunately the rim tape on the back tyre got damaged during the tyre dramas last weekend: it’d been pushed so far to the side that the (non-airtight) protective spoke band was visible, so it’s as airtight as half a balloon and would have to be retaped. But since this was my first time fitting a tubeless tyre, I’m going to start with the easy one.

Before putting the sealant in, the tyres need to be pressurized. This can be traumatic: it’s possible to put the tyre on, inflate with a footpump … and nothing happens; because somewhere along the ~4m tyre edge the air is escaping and the pressure doesn’t build up, unless it’s your blood pressure. Powered air compressors are the best way to inflate them: they push through so much air that the edge leaks can’t do much before the tyre bead is pressurized into place.

There’s a lot of advice on how to fit tubeless tyres at home. Use soapy water on the rim as lubricant, says one source. Scrupulously clean and dry the rim overnight, says another. Stop listening to contradictory advice and buy your own air compressor, says a third. (YouTube is a wonderful source of dubious or conflicting advice.)

If you can get the pressure up, then the tyre bead (ie, the edge) will snap into place along the rim with the most satisfying “bang” noise ever. After that it’s ready for sealant.

The first tyre pressurized almost straight away, I got it up to over 40 psi and it retained pressure so I figured it was all good. I didn’t hear the “bang” noise I’d been looking for, but maybe I just missed it.

Flushed with overconfidence I start on the back tyre. I carefully peeled off all the rim tape, carefully cleaned the rim, carefully applied the new hot pink rim tape, carefully smoothed it all down, carefully pumped it up … pumped it more … and it wasn’t holding pressure. In fact, it leaked like an incontinent puppy.

Taking the tyre completely off is a hassle so I pushed it to one side, smoothed the tape out again, tightened the valve, and tried again: same result. It was a slow leak, so I could trace the sound and air: to discover it was the valve! Bad valvecore? I swapped it out. (Nope.) Bad seating? I retightened it. (Nope.) Bad seal? Hmm … I’d run out of easy options so I took the tyre off (it’s getting easier with practice), took out the valve, and put down another six inches of rim tape over the valve hole, carefully made a small hole for the valve, and reassembled everything.

If you think this sounds too long and drawn out, well, I agree … it was a long afternoon with an uncooperative tyre. Perseverance is key. These things take time.

But it held pressure now! The rim tape around the valve must have been the problem. Even got a small “bang” when I pressurized it! Which almost made it all worthwhile.

Time to do the business outside. I’d ordered a big bottle of sealant, and it came with a tube which fitted nicely around the valve, and around the food-grade single-use syringe I found at the bottom of a drawer. Make sure the sealant doesn’t pool around the valve, or it might decide the valve is a leak that needs to be sealed. Make sure the sealant bottle is airtight again, or it might all dry out. Make sure you do the sealant dance to spread it around the inside, once it’s repressurized. And don’t forget to wipe up the puddles afterwards.

Then go for a cautious trip around the block. No problems that mean we have to stop. But it’s probably best if we don’t go to the park this time. Leave it overnight: in the morning there was evidence of a small leak … but that’s normal for the first few days. It should stop. Try to stay on top of the anxiety …

In the end, tubeless tyres are definitely easier than puppies: they have few hours of problems, but they don’t make a mess inside the house. Toilet-training puppies takes daily work and emotional strain for 4-6 months and the carpet will never be the same again.

But on reflection, the stuffed toy option beats them both.