Originally Posted by
aclinjury
And here's my question to you. Have you or your collegues tested ACCELERATION of a tire? and come away with some quantifcation of the cost of acceleration of using different tire sizes? I ask because, in a race, or even in a spirited club ride, NOBODY is cruising stead-state, people are attacking out of the saddle... and if the tires are squishy.. then the rider is losing major wattage... and losing ground... and we all know that to make up even a few lost positions will cost the rider dearly over the course of a race or ride. I, personally, have found that the larger the volume of the tire, the harder it is to accerlerate the bike to speed,.. it does me NO GOOD if I can be "efficient and comfortable" at cruising speed but lost everything when the attacks come because I cannot keep up... and once you've lost the draft.. it's game over,.. you may resume rolling steady state by all by yourself.
So, I ask, what is your take on this matter of prioritizing acceleration over steady-state rolling efficiency.
So, I've done tests at varying speeds including accelerations (and decelerations) to see how Crr varies. I haven't done 1000+ watt sprints (mostly because I'd need to get out of the saddle to do that which would change my aero drag which in turn makes the rolling resistance drag harder to nail down) but I've done seated accelerations where I went from 150 up to 450 watts over a few seconds. I haven't been able to detect a major change in rolling resistance during these seated accelerations; if there are changes they must be beneath my ability to detect. On the other hand, I can detect pretty small changes in rolling resistance from, say, 3 psi in pressure. So my sense is, if there is an acceleration effect, it's smaller than that.