How often to top up tubeless sealant

Sealant loses its liquid content through the tyre casing and around the bead over time. A wheel hanging in a garage all winter needs topping up in spring exactly as much as one that was ridden.

Zipp's own wheel maintenance material puts the practical figure at around three months. Warmer and drier climates are faster; the number is a starting point, not a law.

Dry sealant does not fail loudly. It fails the next time you get a puncture, which is the one moment you find out, usually a long way from home.

Topping up costs a few minutes and a few millilitres. The alternative is discovering it at the roadside.

Vittoria publishes a six-year shelf life for its tyres. Schwalbe publishes distance figures ranging from roughly 2,000 to 5,000 km for standard tyres, and says plainly that for mountain bike tyres no useful mileage figure is possible.

That spread is why a tracker should show the manufacturer's own figure with its source rather than one blended number. Where a manufacturer publishes nothing, saying so is more useful than filling the gap.

Most maintenance intervals are a proxy for use. Sealant, brake fluid and tyre age are not – they run on the wall clock, which makes them the items most often missed by riders who track only distance.