How to measure comfort?

Picture 1: Flemish cobblestones

When riding a bicycle many factors influence a rider’s sensation: position on the bike, geometry of the bicycle, tire pressures, saddle choice and so on, but if you would look at any of these, the main input will always be the road condition and the reaction of the body to the vibrations the road surface is bringing into the frame. It is not difficult to imagine that riding on Flemish cobblestones will cause more fatigue in a rider than when he would be riding on smooth asphalt.

To start measuring comfort one needs to think about what to measure…

Vibrations are nothing more than excitations in the vertical direction so to measure vertical excitations is to measure the causes of discomfort. The first conclusion which could be made is that fatigue due to vibration is related only to low frequencies (below 50Hz).

In technical literature there is an ISO norm (ISO2631: Whole Body Vibration) that looks at the effects of vibration on the human body. In this ISO norm a typical measuring system is mentioned where you measure the vibrations with an accelerometer at the impact point. After measuring the accelerations a series of calculations are made to obtain a frequency spectrum that can be analyzed for frequency and amplitude.

Picture 2: ISO2631 Whole body vibration test method

Museeuw Bikes Comfort testing.

Picture 3: accelerometer locations

For Museeuw Bikes we adapted this testing and evaluation method to understand the properties of our frame. If we could measure the accelerations at given locations on our frames, the difference in measurements at these locations would give us the reaction properties of the bicycle frame. Museeuw Bikes therefore put five accelerations on the frame and started measuring the accelerations during long test rides on different road surfaces.

After following a 85 kilometer course, roughly 2,5 hours of riding, the accelerometer data was analyzed using a specifically customized method derived from the ISO2631. This analysis gave us the following graphs for the rear stay and seatpost accelerometer measurement.

Picture 4: frequency spectrum of rear stay accelerometer

Picture 5: seatpost accelerometer frequency spectrum

In principle, if you consider a bicycle frame to be a single moving system, the difference in measurements between the rear stays (which is the input of the system) and the measurements at the seatpost (which is the output of the system) gives you the overall damping of the system. This simple calculation performed on the data set gives the following graphical presentation. 0,0 means 0% damping while 1,0 means 100% damping.

Picture 6: damping performance MF5

Museeuw Bikes Benchmark test.

The next question is: “how can we determine our performance?” The answer was simple… to test the competition! Museeuw Bikes set out to test three of its major competitors: Pinarello Prince, Wilier Cento Uno and Cervelo R3-SL. From popular bicycle magazines we had a clear idea on how these frames had been evaluated for comfort and if our test procedure wanted to be realistic, these ideas had should be confirmed somehow by our measurements.

By doing the same routine on these bikes with the same rider and repeating the procedure with 4 different wheelsets the next batch of results was gathered:

Picture 7: damping performance benchmark

From these four graphs the conclusion is not hard to make: the Museeuw MF-5 frame outperforms all the competitors in this test by approximately 20%.