Old 04-09-21, 09:52 AM
  #26  
GhostRider62
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I have done a ton of tire testing in a variety of ways. Really fast tires on real (good) roads might have as low as 0.0042 Crr and pretty good tires might roll at 0.0055 but lousy tires can be as high as 0.01!! If someone is interested in a decent Crr estimate on real roads, temperature stability is critical. RChung method at two speeds lets you get a pretty darned good estimate of Crr. The best I ever measured was 0.004 with GP5000 and latex tubes on good roads, Supersonics with latex also in that range. The rolling resistance figures from drums are generally helpful to order tires but they way, way underestimate real road conditions. My favorite very quick and dirty test is to rolldown a shallow hill from a marked position on a perfectly calm day. I only hit a peak speed of 9-10 mph. Then, I roll on a flat until friction pulls me to a complete halt. I have a control set of wheels. I compare against that control on that day. My testing like that was always aligned qualitatively in rank position to Tom Anhalt's testing. It helps if you think you have a new tire that is bad and sadly, that happens.

The effect on average speed going from 0.0042 to 0.0055 is much more apparent on a very aerodynamic bike like a laidback recumbent. It can be 1 mph. I had found that it was only 1 km/h on my upright. (I am neglecting aerodynamic effects in my statement). Riding at modest speeds like a long distance brevet? Comfort, durability (puncture resistance), and Crr in the order are how I think about it. At higher speeds of say a recumbent or velomobile, other factors come into play. For instance, how does the tire fail? If the casing ruptures spectacularly, you are potentially facing a very serious crash if it happens on the rear of a tadpole trike (velomobile) or the front tire on a recumbent, Aerodynamics are also more important.

The best to decent tires might only cost 10 watts at modest speeds, about the cost of a poorly maintained chain. But 10 cents here and 10 cents there, it eventually adds up to dollars or more poignantly, more sleep in a long brevet.

Personally, I will never again ride a brevet with gravel due to risks on gravel and if the choice was a slightly longer route, I would put fast tires on and just suck it up.

A velomobile rider had some pretty decent tests of the G One Speed, it rolled pretty well but there were better. I have found Schwalbe tires and ultralight tubes to be slower than expected....a bit less average than Compass tires but I do not trust the casings and such a failure on a bent could be death because the speeds are very high on one. The Compass tires are comfortable for sure and they roll pretty well. Me? I only ride Conti.

Last edited by GhostRider62; 04-09-21 at 10:02 AM.
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