I agree with you that it feels that way. The math says that it's a tiny difference, though. For example, accelerate from 0 to 30kph. Do that with light wheels and calculate the energy it takes to get your body+bike moving that speed, and add the energy it takes to spin up those light wheels. Then do the same calculation for heavy wheels, say 1000g heavier. The math says it's about 2% easier to spin up light wheels from 0 to 30kph than it would if your wheel were a full 1kg heavier. That's cold hard math. You and I both know that wheels a full 1000g lighter "FEEL" way faster than 1 or 2%, but there you are. Try and measure it in a test scenario and it would be extremely difficult to do.
If you have a reference to measurements of improved braking distance as a function of wheel weight I'd be really interested to see it. Here's a site that does the accelleration calculations for dozens of wheels, if you are curious. http://www.rouesartisanales.com/article-15988284.html The author is making the point that lighter wheels are absolutely necessary to win at racing, particularly because of the ~2% improvement. The math would suggest that decelleration during braking would have exactly the same ~2% improvement. On Thursday, January 2, 2014 11:09:00 AM UTC-8, Ron Mc wrote: > > it's a little more than that - of course lighter wheels and tires > accelerate more efficiently - it takes less effort to make the bike get up > and go > > On Thursday, January 2, 2014 12:54:29 PM UTC-6, Bill Lindsay wrote: >> >> "the lighter tire/wheel has less inertia, so it accelerates easier and >> brakes much better - these things you can feel. " >> >> Yes, many riders agree with you that you can feel a difference. The >> testing has shown that you can't measure it, though. Lighter tires feel >> faster without actually being faster, according to the data. Since most of >> us ride for enjoyment, and many of us enjoy "feeling" fast, then it's >> probably good enough to feel faster on lighter tires, even though we'd >> actually be faster on wider tires. Jan admitted the same effect. Even he >> is fooled into 'feeling' faster on skinnier tires. He can't leave it at >> that, though. He has to go measure it, and found his feelings deceived >> him. >> >> On Thursday, January 2, 2014 7:48:35 AM UTC-8, Ron Mc wrote: >>> >>> Jim has done a very good job here by comparing different widths in >>> essentially the same high-quality tire - there is no significant weight >>> difference here. >>> Throwing out a data point, my buddy's Tournado on Dahon-specific 35mm >>> Schalwalbe's rolls every bit as efficiently as my Moser on 27-rear/ >>> 25-front Challenge tubies (both bikes on American Classic hubs). >>> A good soft tire with high tpi casing will have a spherical contact >>> patch, while a skinny hard high pressure tire will have an oval contact >>> patch of essentially the same area, so there is little difference in that >>> effect on rolling resistance. There is a good argument that a heavier tire >>> with low rolling resistance will go just as fast a lighter tire - while >>> that's true, the lighter tire/wheel has less inertia, so it accelerates >>> easier and brakes much better - these things you can feel. >>> >>> On Thursday, January 2, 2014 9:12:10 AM UTC-6, Jim Bronson wrote: >>>> >>>> Where does tire weight factor in to all this? I personally find >>>> lighter tires to be faster for the most part, whether they're 23mm or 38mm >>>> (the widths I am running on my Paul Taylor and Rivendell respectively). >>>> >>>> >>>> On Thu, Jan 2, 2014 at 8:21 AM, Jan Heine <hei...@earthlink.net> wrote: >>>> >>>>> Even though most RBW folks may not care all that much about going >>>>> fast, it's still nice to know that a wider tire doesn't roll any slower. >>>>> We >>>>> summarized the data in our blog here: >>>>> >>>>> http://janheine.wordpress.com/2014/01/01/tires-how-wide-is-too-wide/ >>>>> >>>>> If anything, it may help persuade those we meet on our rides, who look >>>>> at our bikes and are intrigued by the idea of a more comfortable bike >>>>> with >>>>> wider tires, but are afraid they won't be able to keep up with their >>>>> friends if they add 5 or 10 mm to their tire width. >>>>> >>>>> Happy New Year! >>>>> >>>>> Jan Heine >>>>> Editor >>>>> Bicycle Quarterly >>>>> www.bikequarterly.com >>>>> >>>>> Follow our blog at www.janheine.wordpress.com >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "RBW Owners Bunch" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to rbw-owners-bun...@googlegroups.com. >>>>> To post to this group, send email to rbw-owne...@googlegroups.com. >>>>> Visit this group at http://groups.google.com/group/rbw-owners-bunch. >>>>> For more options, visit https://groups.google.com/groups/opt_out. >>>>> >>>> >>>> >>>> >>>> -- >>>> Keep the metal side up and the rubber side down! >>>> >>> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/groups/opt_out.
