Rimpact Tuned Mass Damper (TMD)

Feel the difference with the Rimpact TMD.

Using its mass and springs to absorb and regulate energy for less vibration, better handling, and reduced arm fatigue on descents where control matters most.

Designing and building a TMD for mountain bikes presents its own set of challenges.

A "traditional" TMD is tuned to a specific target frequency, with the aim to return the system it is installed in, back to it's natural frequency. However, with the sheer range of frequencies and amplitudes at play in MTB, caused by changes in terrain, rider input, and suspension dynamics—means that opting for a fixed frequency approach leaves the TMD functioning outside of an ideal operational window when in use.

During development, we discovered that even when targeting a single frequency, the unit still provided noticeable benefits according to accelerometer data and rider feedback.

We realized two things:

The mass is free to be displaced, and when it is, its momentum is temporarily stored in one of the two springs that resist it. When an input force is transferred into the bike, that energy transfer is smoothed out over time, thus reducing the kind of compression spikes riders feel over rough sections of trail. This storing and returning action reduces harsh feedback by smoothing out the time it takes for the full input force to be felt by the rider which is perceived as a reduction in vibration. Benefits of this can manifest as increased front-end grip, chassis stability, lower mental and physical fatigue levels and reduced arm pump on longer runs.

The second realization was that the data we recorded of a static mass in the head tube offered a benefit over no additional mass added to the bike, and that the TMD was a similar uplift in performance again, over the additional Mass. It was the 'active' component of the TMD that made it more effective. A static mass was able to offset some of the input forces, for the same reason that displacing a heavy object requires greater force than a lighter object, but not to the same effectiveness as an equal mass within the TMD's design. The TMD was acting as a "mass with mechanical advantage" as we put it.

While we acknowledge this means the system is not a "true" tuned mass damper in the strictest sense, its real-world performance benefits speak for themselves, offering riders a smoother and more controlled ride. We set out to design a Tuned Mass Damper and ended up with something unexpected yet better than we had anticipated.

Does it make you faster? Yes.

Our testing has shown that on average, riders are around one second per minute faster in blind, timed, A/B Placebo testing. ​​​​Whilst this might not sound like much, extrapolating this out on a long DH track or a full Enduro day this advantage can make the difference from placing mid-pack to being at the sharp end of the finishers.

Features

• Suitable for bikes with a steerer length of 180mm+ - Steerers shorter than this will need spacers above the stem to be compatible, please get in touch if you need further information. Steerer must be 20mm ID at it's narrowest point
• Alu and Steel, Tapered and 1 1/8” steerers, single and dual crown, oval or cylindrical are all compatible.
• 97% Pure Tungsten: 2.17 times denser than steel, this material enables the design to remain compact and fit seamlessly into a steerer tube
• Die Springs: Allow the mass to move freely between the 2 springs and are self lubricating so do not need maintaining.
• IGUS Bushings: 3 options include, all calibrated to carefully chosen frequencies. Fine tune to your liking.
• Tuneable for you: TMD ships with soft, medium and firm spring rates. Easily change out the springs to fine tune to your riding preferences.
• Designed for Steerers: ​​​​​​​Igus polymer bushings allow the mass to oscillate freely between two equally rated Die Springs that feature a precise spring rate, calibrated to 3 carefully chosen frequencies. All this neatly packs into the space inside your fork steerer tube.
• Mass is critical: TMD features Tungsten Heavy Metal Alloy as it’s counter Mass, which has a density over 2.17x that of Steel. This ensures the correct weight is used to counter the typical impact forces whilst being able to hide inside a fork steerer.