FR 541 Rim Specifications

The FR 541 may not be your first rim, but it aspires to be the last. The new rim shape improves impact resistance, allowing you to push harder on the trails. It also enhances pinch flat protection, ensuring a reliable ride on rougher tracks. Build this rim with care, and it will reward you with durability and lightness for a long-lasting performance.

Material

Aluminium

30 mm Inner Width and Less Rolling Resistance

Cross Country wheels are designed to be fast, which necessitates reducing rolling resistance wherever possible. On rough surfaces, rolling resistance can account for up to 69% of the total resistance.

Rolling resistance is defined as: rolling resistance coefficient x weight x gravitational acceleration. The coefficient is influenced by factors such as wheel size, tire section, tire characteristics, tire pressure, tread, and soil.

While many of these factors cannot be controlled by the wheel itself, we can improve tire support. A wider rim enhances tire support, allowing for lower pressure and reducing rolling resistance on rough tracks.

Higher Tire Support Allowing Lower Pressure

During cornering, lateral forces act on the tire, causing the contact patch to move in the opposite direction to these forces.

With a narrow rim, the contact patch of the tire may move outside the rim flange, leading to instability. The tire, no longer supported by the rim, can fold, creating tension and pulling on the opposite bead. This may result in a loss of air between the tire bead and the rim bed, known as tire burping.

In contrast, a wide rim keeps the tire contact patch within the rim flanges, providing better support. This increased support allows for lower air pressure and improved control. Thus, a wider rim can be ridden with lower pressure compared to a narrower rim.

Lower Air Pressure and Less Rolling Resistance

A wheel with low tire pressure will roll better over rough surfaces compared to a wheel with high pressure. This is because the tire can adapt more effectively to the ground. In contrast, a wheel with high air pressure cannot absorb obstacles as well, forcing the bike to move upwards, which is similar to lifting work and increases rolling resistance.

Lower air pressure reduces fatigue by decreasing the amount of lifting work a rider must do. This results in a smoother ride and less effort required to navigate rough terrain.

FR 541 29 30 mm DB VI Specifications