> > > 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 --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en -~----------~----~----~----~------~----~------~--~---
