Tubeless Tire Compatibility
This article reviews tubeless bicycle tire fit.
Tubeless tires have become popular in mountain biking, fat tire biking, cyclocross, and road riding. The tubeless system can increase the contact area of the tire to the ground because they can be ridden at low relative air pressure. This can improve the ride feel and handling. Tubeless tires can offer lower rolling resistance and because there is no inner tube, they are less susceptible to pinch flats.
Bicycle tubeless tire systems are similar to those used on cars and motorcycles. The concept is to have the tire is sealed airtight to the rim bead without an internal inner tube. The air pressure from the tire maintains internal pressure at the bead and keeps the tire inflated.
Depending upon the selection of tubeless system components, there are various degrees of reliability and consistency. It is not considered safe nor reliable to manipulate non-compatible parts in attempting to create a tubeless tire ride.
Tires and rims
In the bicycle industry, an early tubeless standard system was called UST, for Uniform System Tubeless. The UST system is required certain specifications in rim and tire demand. While some of the design features are still being used, the designation of UST is no longer seen.
Rather than the UST designation, tubeless tire systems rely on rim and tire manufacturers making equipment to tolerances outlined in the ETRTO standards (European Tire and Rim Technical Organization).
Manufacturers use terms such as “tubeless ready” or “tubeless compatible” for components mean to be tubeless.
A “tubeless ready” or similar wording on a tire indicates there are some design features to help get an air tight seal to the rim. The bead will generally have a square shape instead of the rounded shape commonly found on inner tube systems. The casing will be stronger than a tire intended for inner tubes.
A tubeless ready rim will have a sidewall with a hooked design, which helps catch and hold the bead. Older rims will appear rounded without a hook shape. The shape of the rim will force the bead up snug against the outer hook, and will have a deep section in the middle to make it easier to remove.
The various “tubeless ready” components may or may not match between manufacturers.
Tape, Valves, and Sealant
The interior perimeter of the rim must also be correctly designed to work as tubeless. The rim channel must be internally airtight. This is typically done with different types of adhesive tapes.
Not all adhesive tapes are acceptable to seal the rim. The tape must be flexible enough to covers the uneven surface around nipple eyelets, and it must be resistant to the tire sealant. The tape can also be used to build up the inner diameter of the bead seat area.
Tubeless valves can vary in design. The base of the valve should create an air tight seal. The valve shaft is threaded and a nut is used to pull the head tight against the inside perimeter of the wheel well.
Tire sealant is also considered a part of the tubeless systems. These sealants vary in chemical make up, and although latex is a common component, they are not necessarily compatible between brands. Clean out the tire carcass if changing brands, using the same techniques as if cleaning up after painting with latex paint.
Bicycle tubeless tire system are an evolving technology. It is a common assumption among rim and tire manufacturers that the tire sealant will take care of any small air leaks or seepage. It is possible to do everything to specification and there still may be some slow leakage. It is important to check often and address any issues before riding.