igus® products in gravity applications at Rimpact

What was needed: Bearings for the TMD in the fork steerer and specially moulded plates for the chain damper with a compact design, low-friction guidance and minimal tolerances.

Requirements: Low frictional torque, robust function and long service life in dirty/wet conditions, service-friendly design, tight tolerances in a small installation space

Industry: Bicycle industry

Success for the customer: iglidur P210 plastic bearings (TMD) and customised iglidur J bar stock cutouts together with iglidur G plain bearings (chain damper) enable low friction, high dimensional accuracy despite tight tolerances, compact integration and long service life, and at the same time they support the service-friendly design of the assemblies. By pre-measuring the plate material, tolerance issues were quickly resolved and the launch was on time.

Rimpact pursues a clear product philosophy: The components should noticeably increase performance without impairing the riding experience. At the same time, the products must be durable and dirt-resistant so that riders can reliably get through the season even in wet British weather.

Ease of servicing is a high priority: Products should be easy to dismantle, clean and reassemble using simple means - ideally without special tools and even under racing conditions.
The main technical challenge: Uncontrolled vibrations in the cockpit and chain slap in the drivetrain lead to instability, noise and increased fatigue. At the same time, the dampening systems must be extremely compact to integrate into existing bike standards.

For the TMD, an oscillating mass should swing as freely as possible in the narrow installation space of the fork steerer. With the chain damper, the goal was to effectively capture the chain’s energy and isolate drivetrain feedback without affecting efficiency.

Mechanically, a defined, low-friction movement of the components was essential. Alternatives such as ball bearings proved impractical due to the bulkiness of the compact cavities. What was needed was a material and manufacturing concept that would reliably adhere to narrow tolerance windows and at the same time guarantee robust, low-maintenance function on wet, muddy trails in typical British weather. Rimpact was also under deadline pressure: The market launch deadline had to be met despite strict dimensional specifications and prototype loops.

With the TMD, Rimpact relies on precisely controlled oscillation of a heavy counter mass between two tuned springs in the fork steerer. The counter mass made of tungsten heavy metal alloy delivers the desired mass effect with minimal installation size. The iglidur P210 plastic bearings enable a freely defined, low-friction linear movement with low maintenance effort. Three spring rates (soft/medium/firm) allow fine tuning to the riding style and route; integration in the fork steerer remains unobtrusive, strong and easy to service.

The chain damper reduces free-swinging chains that generate unwanted drive feedback. An internal spring mechanism captures and absorbs this energy. The defined movement is realised via precise friction surfaces, which Rimpact manufactures from iglidur J bar stock plates. The customised plates, so-called thrust bushes - manufactured by laser cutting and measured in advance together with the customer - ensure the required tight tolerances, guarantee uniform friction conditions and fit into the tight installation space.

The limited space was also the reason why iglidur G plain bearings were chosen here. In addition, clear drawing tolerances were defined so that the dimensional accuracy in the series and the on-time product release were achieved. The result is two robust, low-maintenance assemblies that work reliably in typical gravity scenarios and give the rider more control, less vibration and demonstrably more speed on rough descents.

"I've been loving the Chain Damper! I find it better over other products on the market due to the stiff springs inside eliminating any drivetrain feedback and feeling of the hub engagement whilst riding rough sections."

Ethan Craik, Scott Factory DH Athlete

"Honestly, I didn't think I was going to notice this much difference! I can focus better on braking and my lines and I feel my vision has improved."

Rémy Métailler, professional mountain biker, 4x Red Bull Rampage athlete