How often to replace tubeless sealant, and how much to use

How long tubeless sealant lasts

These are the published figures, each for that maker's own sealant. Other sealants may last a different time.

The two Stan's figures do not agree and sit side by side on its pages, with no explanation in what we read. In our view a one-month gap matters little if you check every three months, the routine Stan's itself advises for most riders.

Schwalbe adds a nuance: once the system is airtight you do not always need to top up, although the extra puncture protection only lasts while active sealant remains. It advises checking and topping up before a race or a long trip.

A made-up example using Schwalbe's figure. At 120 km a week, 2,000 ÷ 120 comes to about 17 weeks, or about 4 months. At 40 km a week, 2,000 ÷ 40 is 50 weeks, and you would have passed 7 months, about 30 weeks, long before that. In what we read, Schwalbe does not say which of the two takes priority; our view is to go by whichever comes first.

How much sealant to use by width

Each maker gives its own table, for its own sealant and per tire.

They do not say the same thing. A 2.0 to 2.2 inch tire measures about 51 to 56 mm (2.0 × 25.4 and 2.2 × 25.4), which falls in Schwalbe's 60 to 90 ml band, while Stan's asks for 89 to 118 ml. If you use one brand's sealant, our view is to follow that brand's table.

A made-up example: two 40 mm tires on Schwalbe's table need 120 to 180 ml in total (2 × 60 and 2 × 90).

What makes it last less

Schwalbe focuses on temperature, which it says makes the lifespan vary a lot. Stan's lists these factors:

• Temperature and humidity.
• How much you ride.
• Where you keep the bike: somewhere cool is better.
• How thick the casing is.
• The punctures it has already sealed.

Schwalbe explains that, over time, sealant dries into a rubber film or separates into latex clumps and fluid. In what we read, neither says how much each factor takes off, so there is no sum to do.

How to check it still works

Schwalbe suggests a needle test: pierce the tread and let the wheel turn. If the hole does not close by itself, it is time to top up, and the new sealant closes that test hole.

These other checks are practical judgement, with no maker behind them in what we read:

• Move the wheel next to your ear: if you hear no liquid, there may be little left or it may have dried.
• With the valve at the bottom, remove the core and push in a thin zip tie: if it comes out dry, top up.
• If you unseat a section of the tire, look for liquid or just dry clumps.

Race sealant lasts less

For its Race Day, Stan's gives a much shorter interval: every 2 to 3 weeks. If you use it, count in weeks. The windows in months above do not apply to it.

Tubeless tire pressure

What was read here gives no specific pressure for tubeless. Schwalbe asks you to respect the maximum for both tire and rim, and if the rim's is lower, to stay under that one. On hookless rims you have to follow the wheel maker's instructions, which can sit well below what the tire allows.

For a starting point, use the pressure calculator. It asks for your weight, the bike's weight and the width, it does not distinguish between tubeless and tubes, and it covers 23 to 50 mm, so mountain bike tires are left out. How long the rest of the tire lasts is covered in the tire guide.

In Pedalytics

Pedalytics is not out yet: it is listed as «Coming soon». Its sealant prompts come from two references: 7 months, the end of Stan's longer window, and 2,000 km, Schwalbe's figure. Those references do not fit a race sealant such as Race Day.

Each ride saves a snapshot of the bike's setup and adds the wear to the parts it had on. Pedalytics does not measure the sealant left in the tire. It gives an estimate and does not replace checking it or a mechanic. To fit it in with your other parts, see the maintenance schedule.