You are right, of course. Tread patterns and construction do affect rolling resistance - just look at the Col de la Vie tires which use the same casing as the Pasela, but the micro-knob pattern makes them significantly slower... It's just that unless you go to knobbies, the tread pattern isn't as significant as other factors, but as you point out, that doesn't make it unimportant.
Jan Heine Compass Bicycles Ltd. www.compasscycle.com Follow our blog at http://janheine.wordpress.com/ On Sunday, May 11, 2014 5:12:20 PM UTC-7, ted wrote: > > Per your results, a Nifty Swifty is ~3% slower than a Maxy Fasty, and > wearing 1.3 mm of tread off a Rolly-Poly makes it ~2% faster. RBW describes > the difference between their stronger and lighter tire variants (i.e. > Nifty-Swify/Maxy-Fasty, Ruffy-Tuffy/Rolly-Poly, JB Blue/Green) as stronger > casing, kevlar belt and thicker tread*. In the case of the Ruffy-Tuffy the > extra tread thickness is said to be 1mm. Scaling your ~2% for 1.3mm result > to 1mm yields ~1.5% which is about 1/2 of the 3% difference you found > between the Maxy Fasty and the Nifty Swifty. Presumably the other half is > due to the kevlar belt and casing differences. > > Your results indicate that, for RBW's tires, the rolling resistance > impacts of changes in casing and tread are similar. > > That supports the hypothesis that rolling resistance is effected by (among > other things) tread characteristics. > > > I suspect the 17% difference you measured between the fastest and slowest > tires you tested says more about variation in tire design philosophies > (which is interesting in its own right), than it does about tire > phenomenology (which is what I was commenting on). > > > Re your more practical day to day rubber meats the road comment: I concur > that supple tires are great. I am very pleased with the GB tires I am > currently using. When they wear out I expect I will buy new Compass tires > to replace them. But that is a bit off topic. > > > ted > > > > * "It's just like a Nifty Swifty without the extra ultra-duty casing, > kevlar belt, extra tread & and it has a folding kevlar bead, not a wire > one.", "It's a Roll-y Pol-y with a kevlar belt and an extra millimeter of > tread thickness.", "The GREEN version is like a plumper Roll-y Pol-y, in > that it has a normal casing and tread, with no beefening-up features > (thicker casing, kevlar belt, extra rubber) that would add weight.", "The > Blue version is the same volume, but has an extra strong casing, kevlar > belt, and thicker tread, so it weighs more." > > > > On Saturday, May 10, 2014 6:16:36 AM UTC-7, Jan Heine wrote: >> >> On Friday, May 9, 2014 3:02:01 PM UTC-7, ted wrote: >>> >>> 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. >>> >> >> You make a good point - you need good measurements before you make >> claims. We did measure the same tire with different tread thicknesses. That >> test is easy - you compare an almost new tire (we rode all tires for about >> 50 miles to make sure they were well-seated and that the casing threads had >> the opportunity to "relax") and a well-worn one. >> >> A worn-out set of Rolly-Poly tires with 1.8 mm tread+casing thickness was >> 2.1% faster than new set of the same model with 3.1 mm tread+casing. So >> it's not insignificant, but it pales in comparison to the differences you >> get from a more supple casing. And the worn-out tires wouldn't last you >> through Paris-Brest-Paris or other long ride... >> >> When we talk about tire performance, we don't just throw out conjecture >> and hypotheses. We spent maybe 100 hours testing tires, analysing data, >> performing statistical analyses, etc. The effects we report are real, and >> they are significant. Tires make the biggest difference at lower speeds, >> where the difference between the fastest and slowest tires we tested was >> about 17% in speed for the same power output. Faster riders have more wind >> resistance to deal with, so they obtain less of an advantage from faster >> tires, but it's still the biggest factor in the performance of your bike. >> >> Perhaps even more important is the way the bike feels with supple, fast >> tires. To me and many others, supple tires greatly contribute to the joy of >> riding. If you really are interested in the topic, I suggest you look up >> the back issues of *Bicycle Quarterly* where we reported the results. You >> find an index by topic >> here<http://www.bikequarterly.com/BQ_subject_index.html>, >> and perhaps your local library has a subscription. If not, ask them to >> order the magazine - many libraries already do - or you can order the >> relevant back issues from us. >> >> Jan Heine >> Editor >> Bicycle Quarterly >> www.bikequarterly.com >> >> Follow our blog at http://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-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/d/optout.
