Sorry if this is a duplicate...
From: Dave Porter [mailto:frogeye@porterscustom.com]
Subject: RE: [CR] Wider = faster
Yes and no.
Old Archibald Sharp (Bicycles&Tricycles) knew and told us before the turn of the century that the trick to speed was keeping the tire(s) on the road surface.
The bottom line is, to me, that there are so many variables involved in this, the most important being frictional, that the results could easily be skewed anyway the tester wanted them.
Cross section, compound, casing material, pressure, rider weight, road surface, temperature, speed , wind speed, rain, ice, gravel, sand, good grief the list factors involved make it impossible to model.
Let's say that I'm going to stick with what works for me. Enough contact to corner at my ability levels, enough fatness to allow some deformation over rough obstacles and enough thinness to look really cool .. ;~)
This is another one of those questions that can and will be taken to extremes, but in the bitter end, it really only matters to about .03 percent of us.
Dave P
BTW, I ride 23's... in response to the other thread..
frogeye@porterscustom.com
Porter Customs 2909 Arno NE Albuquerque, NM USA 87107 505-352-1378 1954 BN2 1959 AN5 Porter Custom Bicycles
cars:
http://www.britishcarforum.com/
blog: http://porterbikes.com/
_____
Dave P wrote:
"So, I'm still on the unconvinced side of the fence. Which one of you wants to tell the current hot shoe that his Kilo record will be on a fat tire?"
Dave, I hope you're using the "reductio ad absurdum" rhetorical technique with tongue firmly placed between cheek and gum! Why would anyone think that a fat tire would be faster on a world class track? As I understand the point of the study (and, in fact, the main point of this whole silly debate), is that when forced through constant cycles of deflection and recovery (think "bumpy road"), a tire that wastes less energy doing so allows more efficient forward motion. Most tracks aren't bumpy enough for this to be an issue.
I personally don't spend much time in the velodrome anymore, and would not consider using my 165g Soyo seta pista tires, pumped up to about 10bar, on our local roads. Even if I wanted to destroy tires that way for fun, I'll bet it would be a harsh ride and not really fast.
25mm is about as thin as I go on the road now, often up to 26 or 27 if I can get the right tire. I'm not winning any local races on these fat tires. Then again I'm not actually entering races, either. But if I did, I would stick with 25mm (or larger) tires. I wrench for a master's triathlete who I have talked into using 25s for courses that include less-than-pristine pavement. He agrees that they give him a time advantage over the lemmings on 19mm tires, and his aging body likes the ride a lot better, too.
In the end, the smart thing is to choose tires that fit the requirements and conditions of the job at hand. Those are the ones (whether smooth, knobby, thin, thick, hard, soft and so on) that will be the fastest.
Dave Ross
Portola Valley, California USA