Rockstop Tire Insert Review

Eighteen months ago, the world of inserts was exploding with new options and approaches. It's been quieter since but we’ve been left with a great range of solutions to choose from. Cushcore still appears the most favoured and well known but small brands like Rockstop provide a different approach to protecting your rim and tire.

Features:

• Options for 29, 27.5 and 27.5 “Wide” rims
• Constructed with a shock-absorbing rubberized polymer
• Manufactured in the U.K.
• Easy installation and no special tubeless valve required
• Works w/ 23–34mm internal rim widths (standard)
  • The 27.5 Wide works with 35–45mm internal rim widths
• Weight: 252g (29-inch version)
• MSRP: 65.00 GBP / 86.00 USD

Rock Who?

Similar to Cushcore, Rockstop wasn’t involved with mountain bikes before developing their tire insert. The company started when riders from the Grizedale Mountain Bike Hire Centre and Urofoam Ltd. came together in England’s Lake District. The riders at GMBHC were after an insert that was easier to work with and not as noticeable when riding. Urofoam are “experts in polyurethane” developing products for the automotive, aerospace and sports industries.

With their knowledge and problem-solving experience using PU, Urofoam were sure they could develop a tire insert that achieved the unique goals of the guys at Grizedale. The Rockstop rim protector is the result.

Rockstop Tire Insert Details

The Rockstop insert feels different than Cushcore or Huck Norris. The material is a closed-cell, similar to the Cushcore, but it feels denser. Looking at the insert, it appears lighter thanks to its slim profile and large hollow sections around the wheel. But on the scale, the dense material pushes the weight to within 10 grams of a Cushcore Pro, which was a big surprise.

With a weight similar to the large Cushcore, on paper the Rockstop insert starts to fight an uphill battle. Rockstop claims the high-density shock-absorbing material can achieve what’s needed with a fraction of the mass used by the competition. It doesn’t affect air pressure dynamics as much either, something that some riders like about Cushcore, and a few others don’t – the GMBHC staff for one. The high-density material is also said to be longer-lasting.

Rockstop makes an interesting point in their marketing material regarding the money and time tire manufacturers spend developing tires. They feel that changing the dynamics of the tire can adversely affect it. Because of this and the requests from their friends in England’s Lake District, Rockstop designed their insert to minimize any change to the natural ride quality of our tires.

Installing the Rockstop inserts was relatively easy and without additional tools, I was able to stretch the insert around the rim, slotting it into the rim bed. I also had success mounting one with a bead of the tire already in place. When installed, I found a similar approach to the recommended Cushcore installation process helped get the tire on. Tucking the bead beneath the insert in the rim bed provided the slack needed to slot the tire in place. Installation was less of a battle than even the relatively easy Cushcore XC.

Rock Stopping

With the bright yellow insert installed and the tires aired up, it’s hard to see anything different. The ability to use a regular valve and the smaller sidewall support from the insert disguises it well. Pinching the tire sidewalls, the insert can be felt but it's subtle, feeling similar to the lighter weight Cushcore XC. During my first times out with the inserts, I noticed a quieter ride, and dampened vibrations through the wheels. I found I could lower pressure, though only a small amount – 1–2psi max – before the tire lacked adequate support.

Although the insert is smaller in overall size, it still provides a strong enough hold on the tire bead, preventing any burping. On a ride where trouble with a buggered valve meant slowly losing air as I went, the insert provided enough support to get through without damage. I ended that ride with 20psi in the rear tire, 4psi below my minimum in the conditions I was riding (drier, faster trails). The soft tire was noticeable but on the final descents, the issue was forgotten and I was able to load corners without burping. Tire squirm and impact protection weren’t where I prefer though. The lower volume of Rockstop means dropping pressure into the Cushcore range is not recommended.

With tire pressures of only 1–2psi below my usual, the insert provided adequate support under heavy impacts, fending off most of the damage I encountered. I was still able to ding a rim through the insert but only while using the thin, front specific Michelin Wild Enduro in the rear. Dropping through a rocky, ledgy section, the tire was quickly beyond its limit, transferring the energy through the dense Rockstop material on one of the edges. I thought it was going to be a flat but thankfully, the Rockstop dulled the blow, preventing any loss of air. There’s a good chance that if it weren’t for the insert, the tire would have been destroyed and the rim at least in need of minor surgery. The dings in the rim weren’t enough to jeopardize the seal and were left as a reminder.

Perhaps because of the time I spent on Cushcore Pro inserts this summer, I didn't find the weight of the Rockstop as noticeable on the trail. The Rockstop insert’s less damped ride and smaller effect on the volume in the tire result in the wheel feeling less cumbersome than when first throwing a Cushcore in. Allowing the tire to rebound and compress more like a regular tire is similar to running lighter settings on a bike's damper settings. Too much damping and the bike can become dead feeling. This change in how the tire reacted made it feel more lively than expected and the weight, less noticeable.

Conclusions

The Rockstop tire insert is similar in many aspects to the lightweight Cushcore XC insert. It provides a small amount of sidewall support and rim protection when compared to the large Cushcore Pro. But it feels more dynamic on the trail, disguising its weight and riding more like a regular tire. The downside is that on the scales, it weighs almost as much as Cushcore Pro while providing the same protection and support as the smaller, lighter XC insert.

Rockstop detunes trail chatter but not as much as Cushcore Pro, which for some can be too much. If you’re not into the dead feeling of the CC Pro or the more challenging installation process, the Rockstop is an interesting alternative. It’s more suitable to regular tires as an added protection rather than making lighter tires and lower pressures possible the way Cushcore does, but Rockstop performs well when used this way.

More on the Rockstop Rim Protector.