Jan: I lost your post with the photo and description of your commuter. Can you send again? I promise I'll save it this time. Thanks.
On Wed, Oct 7, 2009 at 10:22 PM, Jan Heine <hein...@earthlink.net> wrote: > > > > > So, if the only variable you're comparing is width, the > >difference between 30 and 33.3 is significant.< > >> > >> significant? really? what is significantly different about the jack > >> brown and 32 pasela? just curious. > > > >3.3 mm., if the only variable you're comparing is width. That's more > >than a 10% difference. Do you disagree? > > > > The ride and shock absorption of a tire depends on the > cross-sectional area, not the width. And the cross-section goes up as > the square of the radius... so small increases in width bring large > increases in comfort and shock absorption. > > A 30 mm tire has a cross-sectional area of 707 mm2 (radius of 15 mm > squared times pi). > > A 33.3 mm tire has a cross-sectional area of 871 mm2. > > A 40 mm tire has a cross-sectional area of 1257 mm2. > > A 20 mm tire has a cross-sectional area of 314 mm2. > > Thus, as a first approximation, the cross-sectional area of a 33.3 mm > tire is 23% greater than that of a 30 mm tire. That is very > significant. > > And if you go to a 40 mm tire, you almost double the cross-sectional > area compared to the 30 mm tire. > > Compare that to a 20 mm tire with a cross-sectional area less than > half of the 30 mm tire, or a quarter of the 40 mm tire. > > Now you know why I ride 40 mm tires on the bikes that fit them. Even > larger tires might be nice on some very rough roads, but you run out > of room if you want a narrow crank tread (Q factor). > > Jan Heine > Editor > Bicycle Quarterly > 2116 Western Ave. > Seattle WA 98121 > http://www.vintagebicyclepress.com > > > > -- Patrick Moore Albuquerque, NM For professional resumes, contact Patrick Moore, ACRW at resumespecialt...@gmail.com --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bunch@googlegroups.com To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en -~----------~----~----~----~------~----~------~--~---
