Jan, Most things are relative, and the law of diminishing returns tends to apply. Surely there are hysteresis losses in the flexing of tread material as it moves into and out of the contact patch, and also losses due to the casing. Their relative significance for a specific tire may be difficult to measure. Rubber tends to have a high damping coefficient (hence its frequent use in isolators) but on a performance oriented tire there usually isn't a whole lot of rubber there. I don't know how to decide what sort of increase in tread rubber would make sense to compare to adding a layer of kevlar to the casing, but without measuring the speed of tires with the same casing and varying treads I think declaring tread less significant than casing from a design standpoint is premature. If anybody ever put a latex filled tread (like some stout schwalbe tires use) on a light supple casing, Ill bet they would get a very slow tire. From a buyers standpoint, there may more variation in the casing construction of various "performance" tires than there is in their treads. If thats the case then, when buying tires, casing may be more important just because thats what is different.
Do you know of folks measuring the suppleness and hysteresis characteristics of tire casing material? How is suppleness quantified? thnks Ted On Friday, May 9, 2014 2:04:49 PM UTC-7, Jan Heine wrote: > > We didn't test the Jack Browns, but we did test the Nifty-Swifty and > Maxy-Fasty, which are the same tires, only in 650B. The Nifty-Swifty was > about 3% slower. However, compared to other tires, both were among the > slower tires we tested, indicating that the casing has a much greater > influence on the speed than the tread thickness and extra puncture-proof > layer... at least for tires with a relatively stiff casing. > > On a supple tire, the puncture-proof layer might slow you down more, > simply because it defeats the supple casing. If the casing is already > stiff, then adding a stiff layer might not do as much. > > Jan Heine > Editor > Bicycle Quarterly > www.bikequarterly.com > > Follow our blog at http://janheine.wordpress.com/ > > On Friday, May 9, 2014 12:49:40 PM UTC-7, ted wrote: >> >> If you include the rubber in your definition of casing. I am fairly sure >> research has shown that slick tires have less rolling resistance than tires >> with a modest tread (I can't speak to the size of the difference though). >> Similarly tread compound has been shown to have an impact. >> >> Tires with light casings tend to have light treads, and vice versa. Jan >> may have tested Jack Brown tires in both Blue and Green variants thereby >> measuring the effect of the casing reinforcement (as I am not a BQ >> subscriber I don't know). Has anybody tested say the BG Rock n' Road and a >> tire built with the same casing but a tread more like what the new Compass >> tires have? >> >> It is very hard for me to believe that a thicker heavier layer of tread >> doesn't increase the rolling resistance of a tire. I am skeptical about the >> notion of a solid center ridge making a thick tread fast. I haven't much >> idea if that relates to noise levels at all. >> >> On Friday, May 9, 2014 11:41:30 AM UTC-7, Cyclofiend Jim wrote: >>> >>> Most of the analysis of rolling resistance for bicycle tires points at >>> casing construction as a much more significant factor WRT rolling >>> resistance. You can create sound without all that much energy loss, and >>> part of it may be related to the audiological perception of the difference >>> - there's a fair bit of tone/timbre difference which certainly fades and we >>> also probably get used to over time. But, I'm not sure you find much >>> actual friction effect - the deformation of the casing and the ease with >>> which that occurs has greater impact (if I'm understanding Jan's tests and >>> writings, for example). >>> >>> - Jim >>> >> -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
