Originally Posted by
531Aussie
10 to 15 watts?! Hmmm, that sounds VERY high.
The Bike Tech Review guys found a difference of anywhere from 1w to about 3w (I'm not scouring through the numbers again to get the exact difference
), depending on the tyres or tubes used.
Scroll down to the "butyl vs latex" bit; but the differences in the main results list rarely exceed 2.5 Watts difference
http://www.biketechreview.com/tires_old/images/AFM_tire_testing_rev9.pdf
http://www.cyclingforums.com/t/494099/rebuild-a-powertap-wheel-and-calibration#post_4066048
Dave notes it's just a comparison btw, not rigorous Crr testing.
One thing to note, that the rougher the road gets the more advantageous anything "supple" will be in terms of power savings i.e. tires and/or tubes. Technically I imagine a ball bearing rolling along glass would have the lowest Crr, but we know tires that don't deform easily over road chatter tend to roll like bricks.
Here's another link which looks to put the advantage somewhere in between the biketechreview data and Dave's observation: http://bikeblather.blogspot.com/
The Continental4000s is run with both latex and butyl for a difference of 8 watts - for a pair of tires. The biketech data is per wheel, so
double whatever the number is to calculate what the rider is saving.
In addition, we know the biketech data is using Michelin latex, but we don't know what latex/butyl Dave was running or what tubes the blog poster above is using. There's a lot of room for error comparing the findings, and I might be carelessly throwing wild numbers around, but it's probably safe to say latex is faster than butyl.
It could probably be argued 6 or 8 watts is pretty meaningless but that's just the inner tube, and added to a faster tire (a training tire vs. a race tire, fiddling with tire pressures, etc.) it could add up to something substantial. Philippe Gilbert once said "training is a lot, maybe 50%, then the rest is all the small things, one percent here, one percent there...". I'd put the training number slightly higher myself ;P