|F/up ? re wheel topic below: rolling resistance||vindicator|
Aug 27, 2003 12:26 PM
|In the Willet article asgelle pointed out, it is said that a "50% reduction in rolling resistance" offers a much more significant benefit than ANY wheel improvement (aero or weight).
BUT, unlike the aero/weight examples on the wheels, Willet did not specify anywhere I saw what his "before" and "after" setup was to achieve this reduction.
First, I'm assuming that the "rolling resistance" he's talking about here is strictly tire/pavement contact and not something like one hub vs. another with less friction.
So, assuming that I'm using as my "before" something like 23mm Veloflex Pave tires inflated to 100-110 psi, as a 6' 175 lb. rider, what do I have to do to achieve a 50% reduction in rolling resistance? Something tells me that just going to 125 psi won't do it. What about 20mm @125psi? Will a more expensive race clincher like attack/force do the trick? Can you only do it by going to tubulars and running "beyond clincher" pressure?
And what are the non-speed negatives of doing this? All other things being equal, narrower tires at higher pressure require more skill to run through fast corners, right?
|It's called a specious argument||Kerry Irons|
Aug 27, 2003 5:15 PM
|Yes, if you could get this kind of reduction, it would be more significant, but the only way this would happen would be if you started with incredibly high rolling resistance in the first place. This would require badly under inflated tires or way out of adjustment bearings, or both. No reasonably adjusted/inflated bike has this kind of reduction in rolling resistance available.|
|I'm no expert||filtersweep|
Aug 27, 2003 6:19 PM
|nor do I play one on TV- but empirically, it appears wheel hop can become more of an issue at higher tire pressure- where the wheel will not conform to imperfections in the pavement and the wheel loses contact with the ground very briefly. I wonder how much power is lost when this occurs.|
|I'm not either||Ironbutt|
Aug 28, 2003 5:31 AM
|But the tire "experts" refer to this characteristic as "chatter." And it's why those 18 mm tires that were so popular a few years ago have all but disappeared. They had to be run at such high pressures in order to prevent pinch flats that they would not conform to minute irregularities in the road surface, thus adding to the rolling resistance. Not to mention being wretchedly uncomfortable and treacherous in corners.|| |