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Rimpact Tuned Mass Damper Development Blog Part 4 – Placebo Testing

So now we have a working prototype we need to verify its capability. Does the device have a measurable effect on the bike and what can we learn from the test results to modify and optimize the performance. In this post we will be revealing some of the results of tests we have conducted. We hope to show that our hypothesis, that a Mass Damper can provide benefit to Mountain Bikers, holds weight. However, if we find that the data does not suggest a benefit, then we will be equally happy knowing we’ve thoroughly tested and disproven the concept.

We had a suspicion that the act of adding weight to the bike could be all that was needed to yield the results we were seeing and feeling when we rode the bike with the TMD fitted. After all, it’s standard practice to see DH racers use additional weights on their bikes to improve chassis stability and suspension performance. To test for this, we devised a blind placebo test whereby riders would repeat timed runs using one of two units installed on their bikes. Unit one would be a placebo unit, identical in weight and size to the TMD, enclosed in an outer tube to hide its contents. The Placebo unit would be identical to the other unit however have its function locked out to prevent it from providing additional benefit. Unit 2 would be the real TMD, fully operational but also enclosed in a tube to prevent the rider from knowing what they were installing in their bike in-between runs. We ensured the weight distribution of the units was identical and the TMD was silent in operation so as not to offer audio ques. We then tasked riders with conducting timed runs, back to back to back, as many as they could repeat in a session.


As we are fully aware that the variables in this test, such as human mistakes, fatigue, weather and traffic could pose issues, we aimed to gather as many runs as possible, over a range of riders and locations. The assumption was that the small errors and inconsistencies would be eclipsed over time with enough runs and repeated data. The winning unit would slowly gain a lead and we could see trends. We also asked riders to give feedback after every run and at the end of the day guess the correct unit.



As you can see from the results above, the TMD provided a benefit over 8 of the 11 days in this particular testing window. Many more testing days were also conducted with the same or better results; however, we have only included this data in the graph as the other days were performed on varying versions of the prototype. The above data is a static design throughout whilst we looked for consistency. On day 2 and day 6, there were considerable number of reported human errors, trail traffic and condition changes compared with more consistent reports on the other 8 days. Below the same data is visualised to show the improvement in lap time on average.


 As you can see, the TMD consistently allowed riders to go faster, run after run, day after day. The average time improvement was over 2 seconds and the average total lap time was 2mins and 14secs. This puts the advantage the riders gained by using the TMD at just over 1 second per minute of trail time. As you can see there was an outlier in the results on day 9, where the average time difference was greater than the other days. This day seemed to yield even greater results however if we remove this outlier then the results still show an improvement of 1.66 seconds on average over 2mins 10.6 secs. These time differences could be seen as within a margin of error however we have continued to repeat this timed testing, over and over with different iterations of the design and consistently yielded time improvements similar or greater to this early prototype leading us to believe the TMD offers a significant time advantage to riders.

Riders also reported an improvement in feel through the bar during these testing sessions, remarking that one of the units felt “smoother”, “the bike felt more controllable” and “I could always get that line I was going for with Unit 2”. To reiterate, none of the riders knew which unit they had installed at a given time, or which numbered unit was which, but on 9 of the 11 occasions the riders correctly guessed the unit with the TMD installed.

We will be sharing much more data and analysing the results further in the marketing attached to the release of the TMD in the coming months.

In the next post, we will delve into the vibrational data from our testing.

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