Tyre inserts (a.k.a. anti-pinch-flat inserts, tyre noodles etc.) are popular in some markets, but they also are a very polarizing topic, a matter of love and hate. Let’s see if they can be good for you, and what we did to make one that stands apart from the rest.
WHY TYRE INSERTS WERE CREATED IN FIRST PLACE
Tubeless tyres (with sealant) are surely helping to keep punctures to a minimum, but they don't totally eliminate them. With the right force, especially on rocky terrain, it's possible to pinch-flat a tubeless tyre, cutting the tyre by pushing it very hard against the rim. Also rims can be damaged in those circumstances.
To avoid that, some brands started offering tyre inserts, some flat, some round (like donuts) some in between (for example, round towards the rim, flat towards the tyre).
These products have become popular among racers, especially for gravity disciplines (Enduro, DH, with some adopters even in cross country): they virtually eliminate pinch flats and - in some cases -also allow the rider to continue riding after a puncture.
COMMON PROBLEMS OF TYRE INSERTS
We list here below the main limitations of current tyre inserts, explaining how Tyreinvader is designed to overcome or mitigate them.
Typical insert weight starts at 100 g and goes up to over 250 g per wheel. While that can be ok for Gravity purposes (or e-bikes), it becomes problematic for a bicycle that has to be pedaled uphill. Heavy wheels always slow down the handling, no matter the practice.
Tyreinvader starts at 50 g (Tyreinvader 40) and reaches 90 g for the widest, Plus-ready Tyreinvader 60. Some brands encourage riders to switch to lighter tyres to partially compensate with the weight increase. We don’t agree with that, as light sidewalls offer limited protection against sharp rocks and abrasion, something inserts can’t do much about.
Radical change of tyre feel
Most inserts take up much space inside the tyre inner cavity, reducing the air volume and the influence on the tyre feel of the inflating pressure (as the insert is often compressed during normal riding, not just on heavier hits). Some other inserts take the concept to the extreme, completely filling the tyre.
We don’t discuss the validity of this approach, we just chose with Tyreinvader to allow riders to use pressure as the main parameter to tune their tyre behavior. You might still feel Tyreinvader inside your wheels, so a test ride is recommended before you race with it.
Some "spongy" inserts end up sucking the sealant completely... preventing pinch flats but exposing the tyre to simple punctures. Tyreinvader is made of EVA, a closed cell polymer, and won’t absorb any liquid.
As inserts have surfaces that are wetted by the sealant, a fraction of it won’t be available to move around to do its job. For this reason, also with Tyreinvader we recommend to slightly increase the quantity of sealant normally employed, by 30 ml.
Tyre inserts can be very difficult to mount.
Tyreinvader only requires average mechanics skills: if you can mount a stubborn tubeless tyre, our insert won’t be able to resist you!
If needed, Tyreinvader can be first mounted on the wheel without tyre, to stretch and make successive mounting easier.
Special tubeless valves
Because of their round shape, some inserts sit on the base of the tubeless valve once mounted, and will prevent proper inflation unless using special tubeless valves (often provided by the insert maker, but normally quite heavy). Tyreinvader won’t interfere with inflation, with any tubeless valve.
We’ve seen inserts destroyed after a single descent in tough conditions, as some foams are not made to resist repeated impacts, just to cushion them and break in the process.
We use EVA, a closed cell polymer commonly used for sport shoe soles, with very high energy absorption and great mechanical properties.
There are other premium inserts with a good durability, but they normally weigh/cost much more than Tyreinvader.
Run flat mode
Rolling with no pressure in the tyres should only happen in emergency situations. In that event, inserts that fit loosely inside the tyre (often to make mounting them easier) are only pushing the tyre against the rim passively, because of rider weight.
Tyreinvader is tight on the rim by design, to help keeping the tyre on the wheel in case of emergency.