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Mountain Bike Tire Inserts Explained

Mountain bike tire inserts explained

The last few years have seen a rising popularity of a new product in the world of mountain biking: tire inserts. What essentially is a piece of high density foam has become something of a must-have accessory for mountain bikers who often ride on rough and aggressive terrain.

What exactly are those newfangled tire inserts? Do they have actual performance benefits or are they just a fad? If they actually work well, should all mountain bikers be using them? In this article we answer these questions and help you decide if tire inserts are something that you’d benefit from, or if you’re better off spending your hard-earned cash on a new pair of riding shorts.

What is a tire insert?

In the simplest terms, it is a circular piece of foam that sits around the diameter of the rim, filling some of the inner volume of the tire and providing protection against rim strikes and damage due to big hits where the tire’s carcass and air volume wouldn’t be enough to deflect the blow to the rim.

Tire inserts are typically made from high-density closed cell foam. The materials used can slightly differ in shape or exact construction, but they are all essentially the same idea. The foam used is also resistant to fluid absorption to prevent it from soaking up the tubeless sealant inside the tire.

Advantages of using a tire insert

  • Rim protection: Running low tire pressure is great for superior traction, but it comes with a major downside: rim strikes. If you’re riding aggressive terrain at high speed, your wheels are subject to big hits that come from roots or rocks that could potentially damage the rim. With those square edge hits, at best you can tear a tire sidewall, and at worst put  a big dent or crank in your fancy tubeless rim. Tire insert are a second line of defense against this. The closed-cell foam provides a layer that absorbs the force of the bump that a tire with a typical ideal tubeless air pressure, with no insert, may fail to fully absorb.
  • Reduce tire deflection under hard cornering: a good insert will give the tire more structure and improved sidewall support, and thus make it less susceptible to rolling right off the rim when subject to lateral forces in high speed corners.
  • Improve cushioning: a foam has a damping effect that reduces trail chatter and makes for a better ride quality. This will result in a smoother ride.

Given the above list of benefits of using tire inserts, it stands to reason that there is little doubt that inserts aren’t just a fad or an over hyped product, but an accessory with significant advantages to riders pushing their bikes to the limits, like elite enduro and DH riders.

But what about the rest of us? Would the average mountain biker benefit from tire inserts?

The answer is: it depends. Tire inserts are not just for elite enduro and DH racers. Consider the below scenarios of use:

  • Heavier riders: strong and heavy riders place more dress on their wheels, and one of the most common complaints of my clydesdale riding buddies is how they keep killing their rims, especially if they tend to ride aggressively. These riders would certainly benefit from tire inserts.
  • Additional protection for your fancy and very expensive carbon wheels: did you just splurge on a pair of lightweight carbon wheels? Even if you don’t race or aren’t particularly rough on wheels, tire insert would be a cheap insurance compared to the cost of replacing a cracked carbon rim.
  • Do you just want a smoother ride? Some tire insert manufacturers claim that the benefits of their product goes beyond rim protection.

Disadvantages of tire inserts

While inserts have several great benefits, as previously outlined, they do come with their own set of downsides..

  • They add rotational weight: tire inserts add weight to the worst pace you can add weight on any bike: the outside diameter of the wheels. The weight can be up to half a pound, depending on the type of insert used. 
  • They complicate the process of flat repairs: A sharp rock can still tear your sidewall, even with the added protection of tire insert. In such a scenario where you’d have to put in an inner tube, a tire insert will just make things more difficult.
  • Cost: how expensive can a piece of high-density foam be? Well, you’d be surprised! Most of them are at least $100.

Conclusion

There is no denying that tire inserts are a worthwhile product to add to your mountain bike, but they do come with a set of compromises that you must consider before buying them. If you don’t want to add rotational weight to your wheels (I am looking at you, XC racers) or rarely have any issues with denting rims or breaking sponges, then there is little point in installing tire inserts. On the other hand, if you are a heavier rider with a history of being hard on wheels, if you ride gnarly terrain, if you race enduro or DH and want added flat protection, or if you are a weekend warrior in search for a more comfortable ride, then maybe a little added weight will and a lighter wallet will be a small price to pay for the added durability, peace of mind and improved ride quality.