Testing of tyre rolling resistance using rollers - Part 2, Setup improvements

Following on from Part 1 of the roller testing described in the previous post, I made a couple of important improvements:

Speed Sensor: In my Part 1 blog post, I explained that I didn't yet have the magnetic Garmin speed sensor that I'd ordered.  I subsequently received the speed sensor through the post and installed it in a similar way to how Tom Anhalt did, setting the 'wheel circumference' on my Garmin head unit to 261mm, which is the measured roller diameter of 83.0mm, multiplied by pi.

I'm still a bit surprised the speed sensor works with the magnet triggering the sensor so quickly, at about 40-50 Hz (every 2-3 hundredths of a second!).   

Front fork mount: Previously I had to prop myself upright using my elbow.  I built a fork mount using a spare piece of chipboard flooring and a few spare bits of timber.

The axle itself is the axle clamp borrowed off my Thule 561 bike carrier (the 561 is now discontinued). 

After making these two improvements, I wanted to check the effect on the rolling resistance measurements by re-doing the runs at 80 psi, using my road bike and Continental GP5000 tyre, as tested in Part 1.  The results below (shown with blue triangle symbols) show that these two set-up improvements have quite a small effect on the results.  It's quite reassuring that one week later, with some tweaks to the setup, I get very similar results to the previous weekend.