Today we present an insert for tubeless tires, studied and tested on enduro race fields, the Gummer.

The Gummer is a high-tech polymer structured multifunction system compatible with all types of tires, valves and latex.
In other words, it is an insert that adapts perfectly to the variations of soil that the rubber undergoes. It models based on the roughness following the slow or fast return of the tire.

As much as its appearance, it has three grooves and some holes that allow the passage of air and latex. There is also an increased hole near the valve to facilitate inflation and deflation.

When it comes to weights and sizes, there are three versions: M, L or XL. The first is to be considered for tires and cross country sections, the L instead is the most used measure in the mountain and enduro as it covers a range ranging from 2.2 to 2.5, while the last size is to be used for wheels plus.
It is also possible to mount an XL on a 2.5 tire based on how much the rider wants to have the tire more or less full.
The weight is 270g on the intermediate measure (L).

Last aspect to consider is the packaging.
Again, nothing was left to chance. It comes individually inside a recyclable canvas bag with assembly instructions included!


Andrea’s been testing it for about a year. It’s been mounted at the front and at the rear on the bike that it uses for long alpine tours, enduristic trails and some bike park outings.
The bike in question is a hardtail trail – all mountain steel with aluminum wheels with 30mm channel and tires WTB Vigilante (2.5) and Trail Boss (2.4) in light version.

In this case, Andrea chose the L version, preferring a ‘less full’ rubber.

Our tester loves low pressures (also to best support driving with the hardtail). With the Gummer he pushed 1.2 to both the rear and front.
The uphill sensations were a great comfort and “fullness” of the tire, especially when dealing with long dirt roads where comfort must prevail. Instead, on more demanding sections, the Gummer helps to have greater traction while maintaining low pressures.

We’re going down the hill. In the corners, despite the low pressures, you have the feeling that the tire does not spill out, the bike is firmly on the ground and you have a great grip. On the bump from ‘that extra safety to leave the brakes and not be afraid to pinch or knot the rim.

In essence, the Gummer is softer than some other competitors, thanks to the closed-cell polymer used. This means that during use the roughnesses are absorbed well and you do not have the impression of having an insert inside the tire.

The assembly is a bit cumbersome as for all other inserts, but once acquired the technique is very simple. The grooves favor the flow of latex and air, the increased hole to be placed near the valve ensures the correct flow of air during inflation and deflation.

After about six months it was dismantled and shortened once because, like most inserts, it tends to stretch with use. During this phase, the insert has remained of the same consistency as when it was first mounted and to date it is still inside the tire keeping its characteristics intact.