Rimpact Tuned Mass Damper and Chain Damper Ridden and Reviewed

Rimpact is a small, rider-owned company based out of Bristol, UK. What started as a tire insert manufacturer grew into a company that specializes in products that improve the ride feel of your bike. Essentially, the folks who started and run Rimpact were thinking about what other products would provide a similar improvement to the feel of their bikes as the tire inserts. Rimpact has developed two products I’ve been interested in: a Tuned Mass Damper or TMD that installs inside the steerer tube of your fork, and a Chain Damper that replaces your chain ring.

TMD V2

The Tuned Mass Damper (TMD) V2 is the second variant of this device. The TMD installs into the steerer tube of your bike and is essentially a Shake Weight; a mass suspended between two preloaded springs. The TMD retails for $375 CDN. The TMD weighed in at 333 grams without the hex extenders. The moving mass portion is 245 grams.

Installation of the TMD V2 was a breeze. Removing my old star nut was the hardest part. Once that was removed, I checked the length, added spacers to ensure I could preload the fork, and tightened down the bolt. I used some slick honey on the sliding elements to keep the TMD running as quietly as possible.

I immediately noticed the TMD on the bike. Initially, there was a slightly strange sensation as I could feel the mass absorbing trail vibration and impacts. I quickly noticed I was getting less fatigued on long abusive runs. The TMD seems to shave the peaks off the biggest impacts, which meant abusive trails that I normally struggle with arm pump on were much less physically demanding.

Durability-wise, the TMD was a good piece of kit. The springs did fatigue and fail after a summer of use. I heard a strange rattle forming, so I pulled the TMD to inspect. Removing the broken springs took all of 2 minutes; I let the Rimpact folks know, and I had replacement springs later that week. Rimpact claims this is the only time they’ve seen the springs fail. I have put in a ton of mileage in bike parks on the Sender this summer, so hard to say if this was riding volume or bad luck. Going back to riding without the TMD was eye-opening. Without the TMD, brake bumps and bomb holes sent so much more impulse through the bars. I was relieved to get the replacement springs and have the TMD back on my bike.

Chain Damper

Similar to the TMD, the intent of the Chain Damper is to isolate external forces from the bike. In the case of the Chain Damper, this device allows sprung rotation of the chainring backwards relative to the crank. As the chain whips up and down through rough sections of trail, the chain damper allows rotation, thereby reducing the reaction of the chain whip forces into the bike.

The Chain Damper retails for CAD $356 for the analog bike version and $375 for the e-bike version. Rimpact sells Chain Dampers that fit the vast majority of crank standards, Avinox and Bosch e-bikes. Chainrings from 30-tooth to 36-tooth are available. The Chain Damper weighs 240 grams, which adds roughly 120 grams to the bike.

Installing the Chain Damper on my Race Face cranks was a 1-beer job. Cranks off, chainring off, Chain Damper on, torque to spec, cranks back on, torque to spec. The quality of the parts appears high, and the fit with my Race Face Atlas cranks was perfect.

I’ve only had the chain damper for a few weeks. Pedalling the bike to the chairlift was my first impression, and I did not enjoy the sensation. Standing while pedalling at a low, easy cadence highlighted how uneven my pedal strokes were, plainly obvious as I repeatedly hit the end stops of the chain damper, then unloaded with each pedal stroke. However, as soon as I dropped into my first descent, the effect the Chain Damper had on my bike was significant.

I ride the Whistler Bike Park a lot, and with that, I intimately know how my bike feels and responds. My bike suddenly felt muted and quiet. Vibrations and shock all seemed to be turned way down. I’m so impressed with how much of a positive influence this Chain Damper makes to the feel of my bike. Descending, I’ve got used to the slightly delayed engagement of the chainring, and can’t say that this feels like a detriment. I’ve learned to smooth out my pedalling stroke on easy efforts too, minimizing the negative effect of the Chain Damper. The weight penalty and strange pedalling sensation to the lift melted away after the first few runs, and now that I’ve had a couple bigger days on the Chain Damper, I can’t see myself going back to a regular chainring. My bike just feels so damn good with the TMD and Chain Damper installed; it’s transformed the bike into a magic carpet.

Durability-wise, I haven’t run the Chain Damper long enough to comment. That said, Rimpact offers all the small parts and rebuild guides, and rebuilding looks quite easy with simple tools. Rimpact claims their intent was to have a low-maintenance product with this Chain Damper, and it certainly looks well put together.

Before trying the TMD and Chain Damper, I felt like these types of devices were a bit snake oily. I’d heard folks talk positively about both types of devices, but most folks’ impressions sounded a bit placebo. No one was able to articulate how or why their bikes felt better. Rationally, I struggled to see how a 245-gram mass bouncing around in my fork could make a positive difference in the ride feel of my bike.

Well, I’m happy to report these devices aren’t snake oil, and they very much make a positive influence on the feel of my bike. I’m ok with admitting that my skepticism was poorly placed. Both devices reduce the amount of vibration and impact transmitted through to my hands and feet. The addition of the TMD and the Chain Damper to my downhill bike has made a huge difference in how muted and planted the bike feels. My hands and body are significantly less fatigued at the bottom of the run, allowing me to ride faster and smoother. Beyond racing against the clock, my bike just feels brilliant. I’ve added half a kilogram, or roughly a pound, to the weight of my bike, and I don’t see myself wanting to ride without these devices. I’m impressed and looking forward to experimenting with these dampers on my other bikes.

Rimpact