Bikeradar tyre rolling resistance test

[wltz]

Thank you, Nereth! Fascinating level of detail!

[scapewalker]

Slightly off topic but do you guys know whether there is a difference in rolling for the front/back wheel because of weight distribution or torque applied to the back wheel?

[C36]

for academical purposes, you will have a different "drag, but not sure it's really making a measurable difference
- rolling losses: the front wheel has less weight = less losses (proportional to weight)
- impedance losses (vibrations): I would like to say that the front wheel may be a bit less impacted since it transmits vibrations more to the front arms than the rest of the body (that is a bigger mass to damp)

[C36]

*Credentials: did my undergraduate thesis on bicycle rolling resistance before I was even into bikes (though I did a shit job and discovered nothing interesting about bike tyres - the thesis focused more on the design of the rig than the actual test results). And now these days one of my responsibilities is technical oversight for an engineering lab that has amongst it's equipment a rolling resistnace rig for a different industry.

Out of curiosity, did it focussed on Hysteresis losses only or did it included Impedance too?

[Nereth]

Drum was smooth so nominally only hysteresis of rubber. But, and I can't emphasize this enough, I learned bacically nothing of note about bicycle tyres. I didn't leave myself enough time to actually run tests on a meaningful number of cases. But I learned a lot about machine design. 10/10 worth it given where my career went

PS: I'm assuming when you talk about impedance you're talking about the hysteresis losses in the human caused by vibration getting through the bike, into the rider. It's a slightly weird word to use for that but I've seen it used for that before so, OK.

[DHG01]

The test design seems fair enough. Very similar to the BRR one.

For once I have some very specific credentials here though*, so I can comment - The problem with rolling resistance testing is pulling out a very small force (the rolling resistance) amongst the massive other forces flying around (vertical load). It's really hard to isolate those two things and not get one leaking into the other in the form of friction in the measurement kit, component forces appearing in other directions, etc.

The trick is in;

a) How you set up your transducers to isolate those loads as best as possible - I was surprised to see both BRR and Silverstone seem to use motor power (Silverstone maybe using motor output torque, a slightly more direct measurement) to do that. That means they also need to take out losses in motor, drum, and wheel bearings depending on measurement location, aero drag from rotation of the system, any other losses that may exist either in torque measurement (torque can be sunk into nominally frictionless supports) or motor power (eddy current losses, etc).

b) Then given the amount of those errors that still exist, how you calibrate them out. A cursory glance at the article/website respectively indicates both of them claim to do so. Neither provides detail on how.

Depending on how the above is achieved, the results could be massively different and with uncertainty literally higher than the test output. I've seen similar devices provide negative readings when poorly devised and calibrated. The best indicator available to us as readers, of useable data, though, is going to be repeatability and agreement across test series, which BRR appears to have an impressive amount of. That could also just be cancellation of errors and an insensitivity to the actual tested phenomena though

*Credentials: did my undergraduate thesis on bicycle rolling resistance before I was even into bikes (though I did a shit job and discovered nothing interesting about bike tyres - the thesis focused more on the design of the rig than the actual test results). And now these days one of my responsibilities is technical oversight for an engineering lab that has amongst it's equipment a rolling resistnace rig for a different industry.

Very interesting perspective; thank you.

[Butcher]

Do any of us just go out and ride a bike and the only tire issue we are concerned about is getting a flat?

[Matt28NJ]

Do any of us just go out and ride a bike and the only tire issue we are concerned about is getting a flat?

Lot's of people on WW geeking out on World Tour level race equipment that will never race (including this discussion).

And that's OK! This can be a fun hobby even if your only tire wish is to never get a flat.

[Nickldn]

Do any of us just go out and ride a bike and the only tire issue we are concerned about is getting a flat?

What Oscar Wilde may have said about Weightweenies:

We live in an age where unnecessary tyre data are our only necessities.

[Jaisen]

Do any of us just go out and ride a bike and the only tire issue we are concerned about is getting a flat?

Lot's of people on WW geeking out on World Tour level race equipment that will never race (including this discussion).

And that's OK! This can be a fun hobby even if your only tire wish is to never get a flat.

We might not be pro level riders or have muscles as big as them, but I am pretty sure our senses work just as well as a pro athlete's. We will feel the same sensations as they do, like if the tires feel sluggish or lack grip, if the bike is smooth or responsive, etc. That's why I never unsterstood when people say you are not good enough for whatever. I think it is just jealously, but then again I have always been a sport tech geek and always enjoyed being on the best equipment I can afford. Keeping up with the latest tech can be a hobby in its own right too. You don't even need to ride the latest gear to enjoy talking about it.