Tire Rolling Resistance
- Thread starter Krazyderek
- Start date
beerco said:
He must have been putting out 21w more then you, and it's that 1 watt difference that let him win eh?
Woofer said:I think we should let people believe what they want to believe. Just think of it as a competitive advantage.
The psychological effects can and WILL make a difference, neglecting that; in a TT even 2 watts would be appreciated. For the reasons already pointed out, I don't put much stock on rolling resistance #'s performed on smooth rollers, but there is probably something in the rankings even if the absolute wattage differences are not real world. That said, I would not even consider using anything other than Conti GP 4000's on clincher wheels... they are the best tires I have ever had (and I have had most on the list, except Michelins) in terms of ride, grip, puncture resistance, and tread life.
wilmar13 said:
After reading here about the 20 watt diff i went to LBS to buy a pair of Mich Race 2s. the shop owner said he really likes the Cont 4000, they seemed to him as fast as the Mich2 but last a bit longer. he is a cat1 and said he races them as well as train on them. with his advice i bought them, i hope they make a $100 difference
zaskar said:After reading here about the 20 watt diff i went to LBS to buy a pair of Mich Race 2s. the shop owner said he really likes the Cont 4000, they seemed to him as fast as the Mich2 but last a bit longer. he is a cat1 and said he races them as well as train on them. with his advice i bought them, i hope they make a $100 difference
I don't know where to begin with this one.
beerco said:
I'll give it a shot.
Since rolling resistance is directly related to the suppleness of the tire, it's usually a trade-off between low rolling resistance and durability. But while it may not be possible to have a tire with low RR and high puncture resistance, it is certainly possible to engineer a tire with neither.
This is where Conti comes in with their tires that are among the worst of the bunch in RR but also have a reputation for fragile sidewalls and being easily punctured. The new 4000 tire appears to be more of the same with complaints already surfacing about easily damaged sidewalls and poor puncture resistance. It appears to be no better than the 3000 in this regard and Vectran simply marketing hype.
http://forums.roadbikereview.com/showthread.php?t=57813
I don't think that's necesarrily true. My guess is that rolling resistance has only recently been brought to the forefront. It's only in the last 2 years that objective (non-industry) attempts have been done to quantify Crr. And while I would agree with your statement in the extremes (i.e. it is probably hard to make a very fast, very durable/puncture resistant tire), a decent combination is possible. One need only compare the Vittoria Open line of clinchers with the Michelin Pro Race2. Almost identical Crr, but the Michelins are far more durable.
It may be hype in terms of durability/puncture resistance (though I would not take a few posts on RBR as proof of anything =), but the 4000 does seem to be a significant improvement in Crr. I've seen several people's field tests now that show Conti made dramatic improvement in Crr over the 3k with this new tire.
Scott
Well, it would be easy to make big improvements upon the 3000 since it's so far down the list.
I hope you're right about the Michelins vs. Vittorias. My new Vittorias barely survived a 4.5 mi HCTT and descent and I've now replaced them with Michelins because they might not survive a road race.
I hope you're right about the Michelins vs. Vittorias. My new Vittorias barely survived a 4.5 mi HCTT and descent and I've now replaced them with Michelins because they might not survive a road race.
scotmart said:
just get a pair of vrestiens or veloflex clinchers they have twice the thread count of Michelins and they are half the price of comparable contis and roll better than the than either...
You can't go wrong with Michelin Pro Race 2, Vredestein Fortezza or Vittoria Open Corsa EVO CX or KS (or equivalent tubular versions) for racing tires. Anecdotally, the Vittoria clincher line seems to be fragile, so I'd stick with the first 2 for road races. These tires have about as low rr as you can get. Deda Tre and Veloflex also make low rr tires but there isn't as much data on them (particularly durability).
All data I've seen says Hutchinson and Conti tires have high rr, so stay away from these.
In our cycling club (we have 2-3 top 20 nationals road racers) Michelin Pro race 2 is used a lot. No conti's. I've been using Vredestein tricomp clinchers and they have low rr and haven't punctured once yet (although I had a couple pinch flats, probably the tube got caught inbetween the rim and the tire).
PS- I've looked at a lot of tire rr data, including Jobst's list and data published in HPV online publications and Tour magazine's tire tests.
-Bikeguy
All data I've seen says Hutchinson and Conti tires have high rr, so stay away from these.
In our cycling club (we have 2-3 top 20 nationals road racers) Michelin Pro race 2 is used a lot. No conti's. I've been using Vredestein tricomp clinchers and they have low rr and haven't punctured once yet (although I had a couple pinch flats, probably the tube got caught inbetween the rim and the tire).
PS- I've looked at a lot of tire rr data, including Jobst's list and data published in HPV online publications and Tour magazine's tire tests.
-Bikeguy
Yes commander Riker? Hehehe, i couldn't resist.beerco said:
There is some data to support his praise of veloflex, their carbon tubular does rate the best in labratory testing for tubular rolling resistance, but doesn't seem they tested any of their clincher's.
I'm still wondering why they can't just cover the big drum with ashvalt to make these numbers more applicable/comparable with the real world.
Anyone got some links to some data on rolling resistance, aerodynamic resistance, optimum air pressure.
I've seen a couple of people's own tests, and they do well, close to the Vitt/PR2's (a little lower, but within the error of measurement).Krazyderek said:
Why do you think that would be more applicable? Crr is determined by the amount of energy lost due to deformation of the tire. On an uneven surface there would be more deformation. The Crr numbers would of course be larger, but there is no reason to suspect the relative differences would change at all.
Scott
scotmart said:
we just don't know is really the point...
but one could imagine that a tire could perform wonderfullly when deformed in a consistant, predictable way versus a random, unpredicable way with variable deflection (anywhere from less than 1mm to probably greater than 15mm) as tires are asked to perform in the real world. for instance i could actually design a tire for this test... make it such that it's walls are super thin and supple (easy to deform) right at the point where it deforms in this test (only one consistant radius with this test) and get really great numbers, but in reality it would likely be just a terrible tire to ride on.. and get much worse numbers when deformed slightly less or more... we just don't know because i've never seen tests like this.
It's not as if a small section of the sidewall is deforming on a drum (or when actually riding). The entire sidewall is deforming. They have done drum tests where they have varried the effective weight on the wheel (thus increasing the deformation), and all that does is give an increase in Crr, but a consistent one. The areas of the sidewall that are 'most' flexible will deform more when a higher load is applied.doctorSpoc said:
But, like every other complaint about the validity of all these tests that have been done, I encourage people to be skeptical and ignore the results. It makes my racing easier =).
Scott
Edit: You can also look at the Tour Magazine results, they tested at different pressures, with the same weight loading. The lower pressures would obviously result in more deformation, and the results are identical (in terms of ranking).
scotmart said:
not really saying that the results would come out this way or that way... just that we don't know... but wouldn't it be nice to see results that actually mimic the real world and just dispense with the assumption associated with using a riding surface that no one will ever encounter. on top of that, we would also get to see more typical real world numbers for Crr that would result. how hard could it be to just texture the drum to put on some texture and simulated cracks... and just dispense with the all these assumptions.
and with the different pressure thing.. don't you want to test the tire at it's optimum pressure (for Crr, handling and comfort)? could different pressures change the dynamics of a tire? i don't know... i suspect they might.. again.. why not just dispense with the assumptions and just test the tires under real world conditions... maybe we learn something we would have never suspected... maybe we get the same results as before but as it stands we'll never know.
The problem with a test that is designed to reflect "real-world" surfaces is that there isn't any such thing. Road surfaces are different. Again, as Scott said, so long as the rankings don't change and the magnitude of the differences is proportional, it's not necessary to test under real-world circumstances for purposes of choosing a tire. For other purposes (e.g., predicting TT times), it would be useful to test on real-world surfaces, but which one?doctorSpoc said:
