Do you need a gravel tyre insert?
After crashing over some sharp rocks on my new carbon wheels I started thinking maybe I should have a look at tyre inserts?
I can’t be the only rider to wince as they hear that “clang” as their wheel pings off a rock. Taking narrow – in comparison to MTBs – tyres off road with low pressures is just asking for trouble. Even with gravel tyres wider than the UCI cyclo-cross legal 32mm, there’s just not enough air to keep your rims safe! If you’re aggressive, heavy or lack the skills to avoid those rocks, maybe you should look at installing a tyre insert? I know I am!
Tyre inserts started off in MTBs, but with the spread of tubeless have made their way onto ‘cross/gravel and now road bikes. Tubeless tyres have allowed riders to drop their pressures, improving grip and control. Previously with low pressures and inner-tubes, pinch-punctures were a constant worry. Run your tyres too low and you risked puncturing on roots or rocks. Put too much in and your tyres would ping off those same rocks and lose traction in soft conditions. Great, problem solved by going tubeless: or was it?
With the lower pressures you now risked damaging your rims: no punctures, but a dent or crack in your rim. And this is the situation I find myself in. Flying down a local trail on my ‘cross bike, I didn’t see a rock and hit it with the rear wheel. Checking the wheel and all seemed good, until at the bottom of a very steep road descent I suddenly felt the tyre lose pressure. Skidding to a stop I checked the rear, I couldn’t see any holes or leaking sealant. So I popped some CO2 in: the tyre inflated and I carried on. Once home and with the rim clean, I could see a small mark on the rim. Nothing serious, but with some big events coming up I thought it was time to talk tyre inserts.
And it’s not just me and my ‘cross bike. You may have seen riders on this year’s Paris-Roubaix – who were riding on tubeless set-ups – suffer some catastrophic wheel failures after punctures. Luke Rowe of Ineos put this down to some teams not running inserts. High speed, combined with lower pressures, no inserts and the cobbles was a recipe for disaster. Luke definitely believed this is what happened.
What are tyre inserts?
Looking around the internet, tyre inserts with one exception seem to work in the same way. A foam “hoop” sits inside the tyre, pressing against the side of the tyre. Some of these hoops come in one piece, others are cut to size and joined in various ways. Once they’re in – and some reviews point to this not always being as easy as the brand’s how-to videos – they provide a barrier between rim and rock. There’s a mixture of shapes and forms, some are flat, some round, some with cut-outs.
Different brands use different types of foam to make their tyre inserts. They all have different qualities, some are dual-density with differing levels of give. As well as being able to absorb impacts, they also have to be tough enough not to crumble away under repeated strikes. Most seem to be closed-cell, so that they don’t absorb your sealant.
Some of the tyre inserts also give varying degrees of support to the tyre at lower pressures: stopping them burping. Many also allow you to keep on riding even with a flat tyre, this can be a massive safety feature, possibly allowing you to stop under control.
But what are the downsides? Well as briefly mentioned they can be difficult to install, but presumably this would be a one time operation. Removing one out on a ride, I think would be a massive pain. If for some reason you had to replace it with an inner-tube, you’d be left having to carry the insert like an old-school Tour de France style rider, wrapped around your shoulders! And it does mean adding extra weight to your wheels, not a lot, but one that could be an issue for weight-weenies. Below is a list of some of the brands out there.
What are the options?
Vittoria’s Air-Liner GRAVEL is a one size fits all tyre insert, you cut it to fit and then join with zip-ties. It has a claimed weight of around 50g, depending on where you cut it. It comes with 3-way valves with horizontal air-holes to allow easy inflation. Being one size it will fit any wheel from 29″ down, with a maximum rim width of 25mm.
The Tyre Invader from Effetto Mariposa pays homage to 80s gaming with its Space Invader cut outs. The reason for these? It’s a combination of weight reduction, making space around the valves and allowing the sealant to move freely. One of the benefits being that you can use any tubeless valves with the Tyre Invader. It comes in five sizes and is another cut and shut insert.
The Rimpact Gravel/XC insert uses a dual-density foam to fine tune the way their tyre insert reacts. The top layer is energy sensitive: it’s soft under minor shocks, but stiffens under hard impacts. The bottom layer is a softer material, soaking up smaller vibrations, while the top handles the hard stuff. It’s compatible with 40-50c tyres and 20-30mm wide rims. A 700c insert weighs 70g and the 650b size comes in at 60g.
These inserts use a completely different method to the others in that they use an inner-tube. This is wrapped around with a foam suit of armour, protecting it from the slings and arrows of outrageous fortune….and thorns.
While it still uses an inner-tube Tannus’s Armour protects your rims, can be ridden flat, is proof against 90% of punctures and is apparently easy to install.
Tubolight’s MTB tyre inserts have been used by Olympic and World champions, so that’s a pretty good endorsement! They put a lot of research into working out why pinch punctures occur and shaped their inserts to prevent this. These inserts also have an air-channel that runs along the inside of the insert. Tubolight say this allows air to move slowly between the outer and inner tyre, creating a damping effect.
I’m keen to try out a tyre insert, racing over rocky terrain with low pressures on carbon rims doesn’t seem the most sensible course of action: but it’s what we do! Not all courses would require it, but events like the CX Century or last year’s Houffa had sharp-edged rocks aplenty just waiting to ping a rim. I’ll give them a try and let you know how I get on.
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