Another insert but this one is yellow!

Rockstop Tire Insert Review

Words AJ Barlas
Photos AJ Barlas
Date Dec 21, 2020
Reading time

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.


  • 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

Something a bit different…

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.

"We're designers. engineers and manufacturers of polyurethane mouldings covering industries including automotive, aerospace and sports. Anything made in PU we are who people come to!” – Rockstop

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.


Less material than many but the special material makes it heavier on the scales than it looks.

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 were approached to create an insert that didn't require much effort to instal and remove and one that would protect the rim and have less effect on the feel of the tire.

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.


In early iterations of the insert, the join was bonded with some glue and pins but they didn't hold. Rockstop removed the pins in favour of simple zip-ties. I've had no issues with them separating since the change.

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.


The design removes the need for special valves and does what they say on the trail. This insert does little to change the way the tire performs.


The overlay is small, but the dense material fends off a good amount of impacts. The insert works best when combined with your usual tire carcass.

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.


Moving to a thinner casing tire – in my case the Michelin Wild Enduro Front – isn't recommended.


With the Rockstop and lightweight tire I managed to ding the rim. The insert prevented worse damage.

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.


Rockstop's insert takes a unique approach that won't appeal to some. But it provides rim protection and some vibration damping properties that others will find appealing, without the lifelessness and perceived weight of others like Cushcore.


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.

AJ Barlas

Age: 39
Height: 191cm/6’3"
Weight: 73kg/160lbs
Ape Index: 1.037
Inseam: 32”
Trail on Repeat: Changes as often as my mood.
Current Regular: Every test product spends time on Entrail

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+4 Mammal Marc Fenigstein DancingWithMyself IslandLife
Agleck7  - Dec. 21, 2020, 6:26 a.m.

You gotta try the Tannus tubeless AJ.


+2 khai Agleck7
AJ Barlas  - Dec. 21, 2020, 7:08 a.m.

I really do. This spring, fore sure.


+4 mrbrett AJ Barlas DancingWithMyself IslandLife
Mammal  - Dec. 21, 2020, 8:47 a.m.

Yep. I have no experience with Cushcore, but I've been blown away by the Tannus inserts. Easy to install, super secure fit inside the tire, very reasonable weight, and good support through corners and rough stuff when running around 2-3 psi less than I'd get away with on my hard tail. They certainly don't add any adverse affects in tire performance, it's exactly the opposite.


Jcmonty  - Dec. 22, 2020, 11:54 a.m.

I am excited to try the Tannus tubeless.  Got one for the rear of my hardtail that I am building (Banshee Paradox).  Interested to see how it compares to the Cushcore XC I have on another bike.  Haven't run the CC Pros


+6 Mammal mrbrett jaydubmah DancingWithMyself Cr4w IslandLife
Bogdan M  - Dec. 21, 2020, 9:43 a.m.

This seems waaaay too heavy for what it is ... I just picked up the Tannus tubeless one .. similar idea but at 1/2 the weight.


+4 AJ Barlas DancingWithMyself Mbcracken IslandLife
Mammal  - Dec. 21, 2020, 10:41 a.m.

There's also a big design difference between the two. Tannus focuses on supporting the sidewall of the tire and adding some impact protection, while these look like they are focusing mainly on preventing rim impacts while maintaining the "traditional" tire-system performance. I'll take the enhanced tire support all day long, thanks!


jaydubmah  - Dec. 21, 2020, 5:59 p.m.

Does anyone know if there will be a Canadian distributor for Tannus? Would love to give them a try, but find shipping from the states a bit pricey. Cheers!

+2 AJ Barlas jaydubmah
Cam McRae  - Dec. 21, 2020, 11:16 p.m.

I believe that is well underway, but I can't confirm the rumour I heard so I'll wait for something official.


+1 jaydubmah
Poz  - Dec. 22, 2020, 5:35 a.m.

A new shop in West Kelowna just opened up called Smith Creek Cycle. They carry Tannus along with a bunch of more unique brands (Pipedream bikes). 

I was going to drive down to get a tannus from them but looks like they may ship


+1 jaydubmah
Jerry Willows  - Dec. 22, 2020, 9:13 a.m.

Kinetic Bike Shop in PoMo had them as well


Bern  - Dec. 22, 2020, 11:27 p.m.

I believe Trek dealers can order them in...

Pete Roggeman  - Dec. 23, 2020, 8:33 a.m.

Yes, that seems to be the case. Obsession Bikes in North Van, for example, carries Tannus (though inventory may be low).


+3 Mammal Cr4w IslandLife
Ryan Walters  - Dec. 21, 2020, 11:13 a.m.

Coming from someone with considerable experience on both CC pro and Tannus tubeless - the Tannus are hands-down the insert for me. Cheaper, lighter, easier to install - and with great sidewall support. I don't know what it would take for me to try another insert, but it would have to be something really special.

+3 DancingWithMyself Agleck7 Andrew Major
Cam McRae  - Dec. 21, 2020, 2:21 p.m.

Agree on many points but I chose CC Pro for hardtail use. That extra damping and impact reduction have made a huge difference. I'm riding the Honzo ESD way faster now and having a lot more fun. I have them front and rear but it might make sense to do Tannus Tubeless front and CC Pro rear. That might actually make sense for a lot of applications particularly because the other element that Cushcore Pro brings is excellent ride flat performance. Tannus tubeless doesn't have run flat capability imo.


+2 taprider Pete Roggeman
Bern  - Dec. 21, 2020, 2:34 p.m.

I'd say the Tannus definitely has run flat capability. It's definitely not "race flat" capable, but I spent 20 minutes with a rear flat and my rim was fine when I got back to my truck. I hated the feeling of riding the squirmy tire but Strava said I wasn't nearly as slow as I thought. So it works for me...

+3 AJ Barlas Pete Roggeman Andrew Major
Cam McRae  - Dec. 21, 2020, 11:22 p.m.

I guess we have a different definition of run flat. You can run flat with nothing in there if you go slowly enough or the terrain is forgiving, but with Cushcore you can ride quite well in most situations and even corner with confidence at reduced speeds. Run flat tires on cars aren't those you can make it home on at a limp, they are tires you can actually drive on, up to 56 mph/ 90 kmh for 10 to 50 miles depending on the tire so my definition parallels that one.


+1 Pete Roggeman
Bern  - Dec. 22, 2020, 11:41 p.m.

Tannus is definitely not as good as Cushcore for run flat, so that's probably fair. 

You had me curious so I went back and checked 1 segment. "Scat" in Cumberland, an easy black diamond trail, KOM is 1:00, my best time is 1:11 and my run flat time was 1:31...


+1 Pete Roggeman
Ryan Walters  - Dec. 22, 2020, 10:03 a.m.

I could see the advantages of CC pro on a hardtail - it definitely has better dampening qualities than the Tannus. One area where I found the CC excelled on my enduro bike was while off-camber cornering across roots and bumps. The CC tires just stuck like glue, not giving up much traction when deflecting off bumps. That "dead" tire feeling certainly helped in these situations.


Lornholio  - Dec. 22, 2020, 11:10 a.m.

Ryan, do you think that the new Tannus offers the same sidewall support and impact protection as CushCore Pro at a givemn pressure, just maybe a little less damping?  I'm likely switching to big wheels next spring so will need to decide whether to stick with CushCore Pro or give the Tannus a shot.  CC has been great for me (except for that one time I landed hard on a very pointy rock...) but curious if Tannus will work for me while giving easier setup and 100g less weight.


MuscogeeMasher  - Dec. 22, 2020, 3:55 a.m.

Agree it's a tannus and CC world. I'm running 2.3's and tannus most of the time on a trail bike and then when I take trips and ride my bike a little beyond its (and my) capabilities, I throw on 2.5\2.4 and CC pro and really like the extra damping in that scenario. Feel like the lower pressures let me get sufficient traction out of the 2.3s (dhf and aggressor) for normal trail riding. Throwing that out there as an idea for fellow nerds/tinkerers.

Hardtail is tannus front and CC pro rear.  If your getting after it on a hard tail and don't have CC pro in the rear you're missing out imo.


+1 jaydubmah
Mammal  - Dec. 22, 2020, 7:50 a.m.

No problems with Tannus on the rear of my hard tail. I definitely understand that Cushcore may provide a bit more flat support in the back, but with the weight/cost advantage, and easier install (I run the same front/rear tires and swap fairly often), I think Tannus is the clear winner for me. The other day another rider in the NSMB comments also said he removed his Tannus insert after a season of riding, and it still looked/felt the same as when he put it in there. Contrasting that to his experiences with Cushcore, where it was all torn up afterward.

I rode out the trail on around 13 psi last weekend, and although I was pretty sure I burped some, it was one of those "maybe it's a bit low" situations.


+5 DancingWithMyself Cam McRae Mammal AJ Barlas IslandLife
Bern  - Dec. 21, 2020, 2:38 p.m.

For me personally I couldn't do without the sidewall support of Tannus/Cushcore. Procore kept me from burping and pinch flatting, but I love being able to ride with 4psi less with Tannus now that I am off Procore.


Sean Chee  - Dec. 23, 2020, 6:40 a.m.

I do find this design intriguing. It's the closest I've seen to an insert that suits my use case. I ride heavy casing at high pressures. As always with inserts, the price is too great an obstacle for me to jump in for my perceived benefits. It's a shame the local tannus distributors are dicks in Australia or I might try those.


Cam R  - Dec. 23, 2020, 12:28 p.m.

I had no probs getting tannus tubeless from bicycles online here in Aus. (I did save a few bucks with a black friday deal)


Cam R  - Dec. 23, 2020, 12:28 p.m.

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