WHY TMD?
Less Fatigue. Vibrations are managed before they reach you. Hands, arms and brain stay fresher for longer, keeping you focused on the trail.
Increases Confidence. TMD V2 smooths out unwanted vibrations delivering a calmer, more confidence-inspiring ride.
Easy Installation. Hidden and secure inside your fork's steerer tube.
Mass That Matters. The 250g mass uses every available space inside the fork steerer for maximum performance.
End Stroke Control. V2 features elastomer bumpers to deliver even more performance on the biggest impacts.
No Tuning Required. Carefully chosen springs with extended travel allow the mass to respond to inputs quicker than ever whilst still offering control through the biggest hits.
IS IT GOING TO MAKE YOU FASTER?
YES.
"That's a product I won't be able to take off my bike for racing... I was 1 second per minute quicker with the TMD”- Jesse Melamed.
SPECIFICATION:
- Unit weight-420 grams
- Mass weight-250 grams
COMPATIBILITY:
Optimised for bikes with a steerer length of 180mm+. If your steerer shorter than this, you will need spacers above the stem to be compatible. Not sure how to measure this? Check our guide here.
Aluminium and Steel, Tapered and 1 1/8” , oval or cylindrical steerers are all compatible. For use on single and dual crown forks.
SERVICING:
TMD is designed so the springs never use more than 80% of their available travel. By avoiding full compression, spring life is significantly extended and replacement is rarely required. Feel free to contact us if anything goes wrong.
FAQ How do I know if this will fit my bike? TMD V2 will fit any bike with a 1 1/8th metallic steerer (almost every fork). Optimised for steerer tube lengths of greater than 180mm, it can still fit those shorter with the use of conventional headset spacers. Check out our installation guide here. Is TMD suitable for Ebikes? Yes! TMD is not only suitable but a great upgrade for your Ebike. Longer ride = greater exposure to vibration induced fatigue. Do I need to setup my fork differently when using TMD? No, just plug and play. We have found the increased composure of the TMD means we ride harder so a slight increase in spring rate and compression helps to make the most of the benefits. Is this compatible with my gravel bike? No, but there is a specific gravel TMD - look at our website. Will it make my bike harder to jump? TMD is largely unnoticeable with respect to jumping and manuals. Does it rattle? No, its easy to securely install your TMD. What tools do I need to install this? Installation is simple, needing only a 4mm allen key and a 10mm spanner.
Review
THEORY BEHIND TMD - SHOCK ABSORBERS
A commonly used device that reduces the amplitude and duration of vibrations in a larger system or structure.
Examples:
- Buildings and large structures, where earthquakes can cause damage.
- In precision instruments, where rotating motors and cutting forces can reduce accuracy.
- In spacecraft and rockets, where strong winds can create turbulence and shake the structure on the launch pad.
- In ships, to reduce the effects of sea swell.
- And a well-known application in Formula 1 cars to control front-end bounce when hitting curbs at the apex of turns.
- Simply put, TMD for bicycles reduces fatigue and increases confidence.
The design and construction of TMD for mountain bikes presents a number of challenges.
“Traditional” TMD is tuned to a specific target frequency with the goal of restoring the system in which it is installed to its natural frequency. However, given the wide range of frequencies and amplitudes at play in MTB riding—caused by changes in terrain, rider input, and suspension dynamics—choosing a fixed frequency means that the TMD operates outside its ideal operating window during use.
During development, we found that even when focused on a single frequency, the unit provides noticeable benefits based on data from the accelerometer and rider feedback.
We realized two things:
Mass can move freely, and when that happens, its momentum is temporarily stored in one of the two springs that resist it. When the input force is transferred to the wheel, this energy transfer evens out over time, thereby reducing the compression spikes that riders feel on uneven sections of the trail. This accumulation and return of energy reduces unpleasant feedback by smoothing out the time it takes for the rider to feel the full input force, which is perceived as a reduction in vibrations. The benefits of this solution are evident in increased front-end grip, chassis stability, reduced mental and physical fatigue, and less arm fatigue during longer rides.
The second finding was that the data we recorded for static mass in the head tube offered an advantage over a situation where no additional mass was added to the bike, and that TMD again provided a similar performance increase compared to additional mass. It was the “active” component of TMD that made it more effective. The static mass was able to offset some of the input forces—for the same reason that moving a heavy object requires more force than moving a lighter one—but not as effectively as the same mass within the TMD design. The TMD functioned as “mass with a mechanical advantage,” as we termed it.
While we acknowledge that this means the system is not a “true” tuned shock absorber in the strict sense, its actual performance benefits speak for themselves and offer riders a smoother, more controlled ride. We set out to design a tuned shock absorber and ended up with something unexpected—but better than we had anticipated.
Rimpact is a Bristol-based company founded in 2018 by Matt Shearn—it was born out of a simple need for better bike components. Frustrated by the available options, Matt designed his own insoles for his bike and soon after sparked interest among friends and other riders, which led to the founding of Rimpact.
Since then, we have expanded our product line to include chain guides for all types of mountain bikes. Building on this success, we have also developed the Chain Damper and TMD—projects we have been quietly working on in our workshop for several years.
We’re still a small team of two, and every product we sell is either manufactured or assembled by us right here at our Bristol facility, where it’s put together with the same care and precision we demand for our own rides.