Heidenau Inner Tube 18 F Heavy Cross – 34G Valve

Heidenau Heavy Cross 18F fits tyres in the 100/100–140/80 size range for an 18-inch rim and is built for extreme off-road loads — motocross and hard enduro.

The wall is thicker than on Standard or Cross tubes — 4.0–4.5mm against 1.5–2.0mm and 2.5–3.0mm. That thickness copes with the impact loads of jumps and hard landings that a standard tube can't handle.

Material and durability

Heidenau Heavy Cross 18F is made from natural rubber: the material resists mechanical stress better than synthetic compounds and retains high elasticity even after prolonged use. On hard landings on track, this reduces the risk of the tube being damaged by ruts and stones.

The trade-off with natural rubber: it loses pressure slightly faster than synthetic rubber, so check pressure with a gauge before a race rather than by eye.

Valve and fitment

Heidenau Heavy Cross 18F comes with a 34G valve — straight-stemmed and threaded for a standard cap, fitting motocross and heavy enduro rims.

Application

Heidenau Heavy Cross 18F suits motocross and hard off-road motorcycles with an 18-inch rim — a size commonly used on the rear wheel of enduro and cross bikes. The Heavy Cross class is not approved for use on public roads — for motocross and off-road competition only.

In Kazakhstan's climate, natural rubber retains elasticity better at low temperatures, but ages faster than some synthetic materials during prolonged use in high heat. Races and training often take place in hot weather, so it's worth checking the tube for wear regularly.

Fitting recommendation

When fitting Heidenau Heavy Cross 18F, use a new rim tape of the correct size and follow the motorcycle manufacturer's tyre pressure recommendations. Pinching the tube with tyre levers remains one of the most common causes of premature tube failure.