First, mountain bike tires were tubed, then tubeless, and now… tubeless with various inserts. There have been a handful of inserts that have popped up recently which all have similar claims. Namely, that they protect the rim and tire from heavy impacts and should keep you from pinch flatting if you manage to strike a rim.
While one of their main goals is similar, the way they go about it is very different. CushCore is one of the newest tire inserts, but to them, it’s more than just a strip to protect your rim and tire. Instead, they look at CushCore as a inner tire suspension system – which results in a damping element as well as a tunable air spring…
The main component of CushCore is an engineered foam insert in two sizes for 27.5 or 29″ wheels. The insert is designed for 23-33mm internal width rims and has a center section that is designed to sit inside the rim channel between the tire beads. At the moment, the inserts are sized to fit 2.1-2.5″ tires, though plus size version are on the way.
Effectively dividing the tire volume in half, one of the biggest advantages of the system according to CushCore is the fact that the insert supports the sidewalls of the tire from the inside. This supposedly allows you to run lower pressures, while still maintaining needed sidewall support. CushCore recommends initially running 5psi less than normal, and fine tuning from there. Referring to the air pocket as the spring, and the foam insert as the damper, CushCore claims the insert helps deaden vibrations, while also protecting both the tire and the rim during big impacts – especially given the fact that the insert covers the entire rim when compressed. According to their tests, the system offers a 50% reduction in vertical impact force, 77% reduction in lateral vibrations, and a 58% reduction in longitudinal vibrations.
The closed cell foam is said to be compatible with all tubeless sealants and won’t absorb fluid over time.
The other piece of the puzzle is the custom valve for the system which allows air to properly flow through into the rim. Since the insert sits directly over the valve, a traditional valve would be blocked by the insert. Instead, the CushCore valves have holes on the side.
Even though the inserts add some weight to each rim, the added grams are said to be offset by the ability to run lighter tires and rims. We picked up a set for testing at Sea Otter and will have actual weights in a post soon. After launching about a month ago, the CushCore system is available for $149 per set which includes two inserts and two valve cores.