Same rear wheel, three punctures in fourteen days, all slow leaks near the valve side of the tube. I've run my fingers around the inside of the casing twice and pulled out nothing. Tyre has maybe 2500km on it. I ride the same route daily, mostly city streets with a stretch of cycle path that gets a lot of broken glass. Running 90psi on a 28mm tyre. What am I missing?
2500km of glassy urban cycle path is roughly the end of life for a normal tyre. Look at the crown for square cuts and embedded specks. When it starts collecting glass faster than it sheds it, that's the tyre telling you. A commuter tyre with a proper puncture belt costs more and lasts twice as long in that environment.
Also drop the pressure. 90psi on a 28mm tyre is high for a commuter carrying a rider plus a bag — you're probably fine 15-20psi lower, it'll be more comfortable, roll about the same on real streets, and pinch flats and rim strike become much less likely. Modern thinking on tyre pressure is a lot lower than what most of us grew up with.
Dropped to 72 and the cycle path stopped rattling my teeth out. Should have done this years ago.
Weigh yourself with the loaded bag once and use one of the pressure calculators. Takes five minutes and most people are running 15-25psi over what the numbers suggest.
Check the valve hole edge too. Some rims have a slightly sharp lip there from manufacturing, and a tube that's been pinched at the valve chafes over a few hundred km. A file and thirty seconds fixes it permanently.
@hive_tool_hal · 6mo ago · 3 replies
Two things to do before anything else.
First, read the tube. Line the hole up with the tyre by matching the valve to the label, then look at that exact spot from both sides. If the hole is on the inner face of the tube — the side against the rim — it's the rim tape or a spoke end, not the tyre, and you'd never find it with fingers in the casing.
Second, use a cotton ball or a folded tissue rather than fingers to sweep the inside of the tyre. A glass shard sitting flush in the rubber is invisible and doesn't cut skin, but it snags cotton immediately.
Repeated slow leaks in the same area with nothing in the casing is rim tape about half the time, especially if it's the woven cloth type that shifts.
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@backbutton_bri · 6mo ago
Rim tape had slipped enough to expose the edge of a spoke hole. Holes were on the rim side and I'd never thought to check which face they were on. Fixed for 300km now.
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@flat_rate_finn · 6mo ago
The cotton ball trick has found me three invisible slivers. It feels ridiculous until it works.
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