tag:blogger.com,1999:blog-6080071290235905056.post1369609547879497867..comments2024-02-27T18:30:46.362-08:00Comments on Blather 'bout Bikes: Why Tire Crr matters...Tom Anhalthttp://www.blogger.com/profile/08175472546482777614noreply@blogger.comBlogger16125tag:blogger.com,1999:blog-6080071290235905056.post-48495170797976466672014-11-15T20:19:44.437-08:002014-11-15T20:19:44.437-08:00Just did a test of my own on the michelin pro4: ht...Just did a test of my own on the michelin pro4: http://teamrodrigo.com/2014/11/15/battle-of-tires-which-one-is-best-in-the-real-world/Rodrigohttps://www.blogger.com/profile/01453140930081798744noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-4913155008924668042013-08-21T10:13:13.634-07:002013-08-21T10:13:13.634-07:00friend can you pass me a excel for virtual elevati...friend can you pass me a excel for virtual elevation robert chung? Thanks!Manuel Ordiñanahttps://www.blogger.com/profile/13234658647808978961noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-89343242546499275922013-08-01T13:21:17.275-07:002013-08-01T13:21:17.275-07:00Very interesting stuff. I love reading your blog. ...Very interesting stuff. I love reading your blog. Always something interesting to catch my eye. <br /><br /><a href="http://www.eppiestire.com/" rel="nofollow">Click Here</a><br />MarktheManhttps://www.blogger.com/profile/18401654212011501724noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-59407828659117511782013-05-03T14:57:40.281-07:002013-05-03T14:57:40.281-07:00In that case, yes...I get ~6W difference to go the...In that case, yes...I get ~6W difference to go the same speed on average.Tom Anhalthttps://www.blogger.com/profile/08175472546482777614noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-8506097235031565342013-05-03T14:45:02.315-07:002013-05-03T14:45:02.315-07:00That's a good question. No wind, non-draft tr...That's a good question. No wind, non-draft triathlon, 40k/hr, so ground speed is 40k/hr too?Greg Ostrinhttps://www.blogger.com/profile/01988573628996245961noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-26643496329863452612013-04-21T10:47:40.295-07:002013-04-21T10:47:40.295-07:00Greg, at what expected apparent wind speed and exp...Greg, at what expected apparent wind speed and expected ground speed?Tom Anhalthttps://www.blogger.com/profile/08175472546482777614noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-104576514035505952013-04-20T09:17:15.389-07:002013-04-20T09:17:15.389-07:00Tom can you tell me if I'm reading that new ch...Tom can you tell me if I'm reading that new chart correctly (the one with the PR4). I did some calculations and at 40km/hr, it's about a 5w difference between the GP4000 and the PR4?Greg Ostrinhttps://www.blogger.com/profile/01988573628996245961noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-36936180983349857212013-04-15T16:59:48.523-07:002013-04-15T16:59:48.523-07:00The methodology and equations (Al Morrison -the or...The methodology and equations (Al Morrison -the originator of that listing - actually uses equations I originally set out for his calculations) between that source and mine are nearly identical. The major differences are the roller material (Al's are plastic while mine are aluminum) and the fact that the Crr value in my table includes the 1.5x "smooth to rough" conversion, while Al's values are for smooth, flat surfaces.<br /><br />If you take the .00307 Crr value that Al measured a few years ago for the GP4000S (when the black chili compound first was added) and multiply it by 1.5, it would end up coming in at .0056 on my chart. Apparently...and I've confirmed the Crr value I measured with a second tire...Continental has been making the tire faster over time. Most likely this has been done with subtle tweaks to the thickness in various areas. To the hand, the newer tires feel a bit more flexible (indicating a thinner coating on the sidewalls) plus the newer tires weigh out at ~200-210g, while the older tires were in the ~230-250g range.<br /><br />As a cross check between the 2 lists, take a look at the Bontrager RXL Pro 23C entry. Al shows a Crr of .00244, which when multiplied by 1.5X results in an "on road" Crr = .0037. I measured a well used model of the same tire at .0035. Doing the same with the Specialized S-Works Mondo Open 23C, you'll find Al's compensated value at .0035, while my measurement is .0034.<br /><br />Bontrager Aerowing TT 19C: .0041 vs. .0042<br /><br />etc., etc.Tom Anhalthttps://www.blogger.com/profile/08175472546482777614noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-35060142244549561252013-04-15T16:52:42.248-07:002013-04-15T16:52:42.248-07:00This comment has been removed by the author.Tom Anhalthttps://www.blogger.com/profile/08175472546482777614noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-19117074337570262872013-04-15T12:16:06.858-07:002013-04-15T12:16:06.858-07:00I love this post, it's a great way to look at ...I love this post, it's a great way to look at things as the combined system is what we're living with on race day obviously.<br /><br />However what I don't understand is how your GP4000S Crr is higher than what I understood to be the canonical source for Crr information (http://www.biketechreview.com/tires_old/images/AFM_tire_testing_rev9.pdf) nor do I understand how e.g. the other tires (R4Aero / Vittoria) were in different Crr rank order vs that GP4000S.<br /><br />Did Conti change the compound? Or is there a (perhaps scientifically interesting) methodology difference between the tests, that could be useful in making a decision?Mike Hardyhttps://www.blogger.com/profile/12368648851858425928noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-40109066483200226062013-04-09T17:27:46.021-07:002013-04-09T17:27:46.021-07:00Thanks guys.
Yeah Dan, I knew that Mavic chart wa...Thanks guys.<br /><br />Yeah Dan, I knew that Mavic chart was close to the one you had estimated, so that made me feel a bit better about using it.<br /><br />Taking it "the next step" is a bit more difficult...I was thinking that analysis like this needs to be combined with your "speed for a given power" modeling attempts ;-)Tom Anhalthttps://www.blogger.com/profile/08175472546482777614noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-91015566394366738112013-04-09T09:35:01.398-07:002013-04-09T09:35:01.398-07:00Very helpful and informative. ThanksVery helpful and informative. ThanksCody Bealshttps://www.blogger.com/profile/09963657383140335035noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-14504062012239073992013-04-09T07:41:18.947-07:002013-04-09T07:41:18.947-07:00Nice! First, that distribution plot looks a lot l...Nice! First, that distribution plot looks a lot like one [url=http://djconnel.blogspot.com/2011/03/yaw-angle-variable-wind-speed-and.html]I estimated based on simple assumptions[/url], so that's nice. But second: there should be a third component, which is how important a particular yaw angle is (you've already pointed out in a road race situation yaw may be less than it is for a solo rider, so I'm talking actual yaw here). For example, if you can barely control your bike in a 20 deg yaw, then either that angle becomes less important (power isn't rate-limiting) or perhaps more important (if stall angle affects stability). Of course, facing such uncertainty, the best approach is generally the simplest, which is what you've done.djconnelhttps://www.blogger.com/profile/01484858820878605035noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-35324638940707611272013-04-09T04:26:16.596-07:002013-04-09T04:26:16.596-07:00Nicely done.Nicely done.Anonymoushttps://www.blogger.com/profile/06289116677029290174noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-63364733290205477182013-04-09T03:26:34.072-07:002013-04-09T03:26:34.072-07:00Fantastic write up, Tom. Excellent resource. Fantastic write up, Tom. Excellent resource. Steve Chttps://www.blogger.com/profile/02509904329785695150noreply@blogger.comtag:blogger.com,1999:blog-6080071290235905056.post-91157476807044147102013-04-08T20:04:09.467-07:002013-04-08T20:04:09.467-07:00Brilliant stuff Tom. Thanks for taking the time t...Brilliant stuff Tom. Thanks for taking the time to put this together. <br /><br />Jon Thornham<br />FLO CyclingUnknownhttps://www.blogger.com/profile/01252882275902945121noreply@blogger.com