Polymer plain bearings in mountain bikes with rear suspension

Choice of pivot points and kinematics

The "ConTrail MGN" is one of the top models in Bergamont's full-suspension mountain bike range. Lightweight iglidur® polymer plain bearings from igus® are used at the dropouts of the rear suspension for heavy-duty applications. The definition of the pivot points plays a very important role in the design of a rear suspension. Thomas Marquardt: "We have a precise idea of how a bicycle should ride and carry out extensive tests during development." This applies not only to the positioning of the pivot points and therefore the kinematics, but also to the choice of bearings. Bergamont originally used ball bearings at all bearing points on its "Fullys". The "Contrail MGN" is the first bike to deviate from this principle. "At the two front pivot points," says Marquardt, "i.e. at the connection between the swingarm and frame, we use deep groove ball bearings because the bearings perform a relatively large pivoting movement here. At the rear joint, on the rear axle, on the other hand, we have taken a new approach this time and are using a plain bearing."

Specialist dealers and bikers completely satisfied

The self-lubricating iglidur® polymer plain bearings promise a long and predictable service life. However, the sales department first had to convince the specialist dealers. Thomas Marquardt: "We had already used plain bearings a few years ago, but they were made from other materials and were too small. That's why there was a need for information and training." However, the dealers are completely satisfied with the current solution, as the feedback from bike owners has been consistently positive. The torsional strength of the bike is very good and the suspension responds very quickly, reports Marquardt.

The very careful design of the bearing point certainly contributes to this. In bike production, the bearings are pressed into the swing arm with slight pressure. In addition, a metal sleeve is inserted into the bearing, which forms the end stop for tightening the screws. This ensures that the bearings remain rotatable even after assembly work by the bike owner.