Rimpact have released their CX tire inserts claiming to provide sufficient tire support to allow for pressures that rival what is possible with tubular tyres. At 55g per insert, Rimpact reckon these are light enough to be practically unnoticeable on a CX setup. Though specifically designed with CX racing in mind, Rimpact say they also work well as gravel tire inserts to mitigate punctures, provide grip and protect rims.
Rimpact CX tire inserts
We haven’t yet had a chance to test Rimpact’s CX tire inserts. However, they do use the same dual density technology as the Rimpact PRO MTB inserts that won our Editor’s Choice 2020. Rim protection, lowered tire pressures and most notably, vibration damping, sealed the deal for Rimpact… thus, I would expect great things from the CX tire inserts too.
Naturally, weight was a huge priority in the design of these cyclocross tire inserts. At 55g they certainly are very light but they aren’t the lightest on the market, however. At 48g per insert, the Effetto Mariposa Tyreinvader is 7g lighter, but doesn’t claim to offer half as many benefits as the Rimpact CX insert… more on that later.
In testing, Rimpact found that their Original foam didn’t scale down from MTB to CX rims very well; protection was compromised. The engineers found that by using two different densities of foam they were able to strike a balance between protection, weight and ease of installation.
You may well expect the harder, higher density foam to sit closest to the rim for protection. After all, suspension is progressive overall so shouldn’t tire inserts be the same? Rimpact have it the other way around for good reason.
The softer layer sits against the rim, supporting the tire whilst acting as a dampener for both vibrations and larger impacts. The harder layer sits at the tire wall interface to provide impact protection and to act as a shell to absorb and dissipate force.
As force is applied (when you hit a rock or square edge) the upper layer of the Rimpact CX increases its protection to dissipate the forces across its body rather than through itself and into the rim it’s protecting. This is also how the inserts are able to offer such great vibration damping qualities.
What are the benefits for the 110g weight penalty?
One of the main selling points of the Rimpact CX tire inserts is that they should allow the running of lower pressures, close to those you might run on a tubular setup, but on clincher tires. Other benefits, and there are many, include the following:
Protection from pinch flats
Mitigate rim damage
Run flat to make it to the finish or a repair stop
Rim protection is what I was after when I got a set of Rimpact PRO MTB inserts in for testing. While they did a great job in that department, it was the vibration damping qualities that took me by surprise.
It may seem like a a fluffy marketing term to some. However, I can tell you from personal experience that, even when run at equivalent pressures, it does translate to a more comfortable ride, less fatigue and thus, going faster for longer. With the lack of suspension on CX bikes, this feature should stand out even more.
Pricing & Availability
£69.99 gets you two Rimpact cyclocross/gravel tire inserts and two 44mm or 55mm Rimpact tubeless valves, designed to be unblockable. The CX inserts are currently only available for 700c wheels, and are compatible with UCI spec CX (33c) tires, any rims with an internal diameter of 17mm to 25mm, and tires in the 33c to 45c range.