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#51
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Nobody knows about RR
Neil Brooks writes:
I thought that makers of bicycle tires would have experimentally or scientifically based knowledge as a foundation of their production. I jumped in late and, unfortunately, haven't caught this thread in its entirety, so forgive me if this has already been posted. Interesting article: Adobe document p.8 Magazine p.14 http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf Along with its testing and conclusions, it makes reference to the following sources (which I haven't attempted to locate) of RR test data: Cycling Plus, issue 62 (Feb. ?97) ?Winter tyres?; Cycling Plus, issue 68 (Mid-summer ?97) ?Road tyres?; Cycling Plus, issue 81 (Aug ?98) ?Time-trial tyres?; Total Bike, issue 6 (Oct ?97) ?MTB tyres?; and BHPC Newsletter, issue 58, ?MTB tyres?. The section on rolling resistance (pp 14) has a disconcerting flavor to it in two ways. First the author attempts to establish credibility through his years as an engineer and long association with recumbents. Then the test method is explained showing that no direct measurements of drag were used but rather the derivation of drag by differentiation of rolling speed. http://www.terrymorse.com/bike/imgs/rolres.gif Printing a table of myriad numbers may be a good archive but such data is better displayed in curves and preferably curves made of more than one data point. What we have in the IHPVA report is none of that. In fact the information shown in the RR graphs above of decades ago is not visible in these data. The article, "On the Efficiency of Bicycle Chain Drives" is particularly interesting as well. I don't see anything interesting in that piece because the measurements are not normalized to be comparable. Behind all this testing is the simple concept that chain efficiency depends on articulation angle for one cycle under load, nothing less. What conclusions are we to draw from these measurements and to what good can they be used? I see this a s a major snow-job that obscures the essence to what the test titles allude. Jobst Brandt |
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#53
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Nobody knows about RR
Jasper Janssen wrote: On 28 Jul 2005 10:00:30 -0700, wrote: Jasper Janssen wrote: On Tue, 14 Jun 2005 20:37:01 -0500, jbuch wrote: Because of the greater dollar and sales volume and greater consumption, there may be a better technology basis in Automotive Tires. At least, in the late 1960's tire companies were out hiring brand new PhD graduates from my engineering school. On the other hand, the confirming data and experiments may be company proprietary, and unpublished. Formula 1 tires, in particular, are extremely well-researched. But the results are also so secret that the actual F1 teams aren't even allowed to touch the tires that the tyre manufacturers provide them with. Must be hard to put them on the car without touching them. I could have sworn that I've seen pit crews change tires in F1 races. You didn't see pit crews change them, you saw tire manufacturer people change them, only nominally part of the team's piut crew. Tires come in their own trucks and have their own people. So you're saying that Ferrari's pit crew that does the super fast tire changes are actually Bridgestone techies cleverly disguised in Ferrari uniforms? I have to admit that with the full coverage helmets they wear these days, they could be anyone. If you get the impression I don't believe that the teams aren't allowed to touch the tires, you're right. I do believe that it's quite likely that tire company techs do the actual mounting of the tires onto the wheels. |
#54
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Nobody knows about RR
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