jens wrote:
It's also why, at some very high speed, an aero, but slow-rolling tire like the Conti GP will actually outperform an un-aero, but fast rolling tire like the Corsa Speed.Triathlon Forum
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Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C) [jens]
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And, interestingly, (as someone who sometimes works with women riders) this tradeoff depends on rider weight.
Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C) [jens]
[ In reply to ]
jens wrote:
devashish_paul wrote:
So that's why if the grade is steep enough and you go slow enough rolling resistance and air resistance trends towards nothing and you can almost get an approx of your FTP power by taking mgh/time, where mass is all mass of bike+rider+gear, h is vertical displacement, g is 9.8m/s^^2.It's also why, at some very high speed, an aero, but slow-rolling tire like the Conti GP will actually outperform an un-aero, but fast rolling tire like the Corsa Speed.
Uh wut? Can you share the math on that.
By my spreadsheet, it would need to be a heavy cross headwind on an unfaired wheel.
Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C)
[ In reply to ]
So what do you give up by switching from a Conti GP4000SII to the Vittoria Corsa Speed G+ ? Is the Vittoria much more susceptible to punctures?
Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C) [jens]
[ In reply to ]
jens wrote:
Some roller test fun today.
Continental Grand Prix GP4000 S II 25C: .00343 (50 miles wear)
Continental Grand Prix GP4000 RS II 25C: .00343 (new)
Continental Grand Prix GP4000 S II 23C: .00343 (new)
Continental Supersonic 20C: .00270 (new)
Continental Supersonic 20C: .00253 (200 miles wear)
Continental Supersonic 23C: .00279 (new)
Vittoria Corsa Speed Pista 23C: .00262 (100 miles wear)
Vittoria Corsa Speed 25C: .00241 (new)
The surprises are that the vaunted GP RS is no faster than the normal model. And the 23C GP rolls just as fast as the 25C GP tires.
What's more surprising is that the 23C Supersonic is actually a bit slower than the 20C version. In fact, my worn SS 20C is one of the fastest tires I've ever tested. Why is it so much faster than the new SS 20C? The wear? Continental's inconsistency? I'm not sure.
For Vittoria, wider is definitely faster. The 25C Corsa speed tire is worth around 2 watts over the 23C. I think lanierb only got a 1 watt difference. In a previous test, I got 1.6 watts.
Question: how hard were the 25C Corsa to mount?
Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C) [Karl.n]
[ In reply to ]
Karl.n wrote:
jens wrote:
It's also why, at some very high speed, an aero, but slow-rolling tire like the Conti GP will actually outperform an un-aero, but fast rolling tire like the Corsa Speed.Uh wut? Can you share the math on that....
Rolling resistance increases linearly, while wind resistance increases exponentially. So at some speed, a more aero setup has to surpass a better rolling one. I'm too lazy to calculate that speed for you, particularly since it's dependent on the rider/bike weight and the overall drag. As lanierb wisely points out, that speed would be lower with a lightweight rider.
My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers
Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C) [SBRcanuck]
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SBRcanuck wrote:
So what do you give up by switching from a Conti GP4000SII to the Vittoria Corsa Speed G+ ? Is the Vittoria much more susceptible to punctures?The CS is definitely much thinner. I can't speak to puncture resistance, though I would guess that a lot of the stuff that might puncture one tire would puncture any tire.
GreenPlease wrote:
Question: how hard were the 25C Corsa to mount?It was definitely easier than the 23C. However, I found that once I was careful to keep both beads in the center groove (of Hed and Enve wheels at least), mounting became vastly easier with all these tires. I was able to mount the CS Pista with no tools at all; the CS 25C only required a little lever use at the end.
My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers
Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C) [jens]
[ In reply to ]
So for a 205 lb rider is the GP 4000s ll the best tire say with avg speed of 23 MPH?
Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C) [RBR]
[ In reply to ]
RBR wrote:
So for a 205 lb rider is the GP 4000s ll the best tire say with avg speed of 23 MPH?This is something you can check for yourself, plugging in the Crr numbers provided at the top:
https://www.analyticcycling.com/ForcesPower_Page.html
Ceteris paribus, the heavier you are, the more rolling resistance matters.
My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers
Re: The foolish inconsistency of Continental tires (Plus Vittoria CS 25C) [GreenPlease]
[ In reply to ]
jens wrote:
SBRcanuck wrote:
So what do you give up by switching from a Conti GP4000SII to the Vittoria Corsa Speed G+ ? Is the Vittoria much more susceptible to punctures?The CS is definitely much thinner. I can't speak to puncture resistance, though I would guess that a lot of the stuff that might puncture one tire would puncture any tire.
GreenPlease wrote:
Question: how hard were the 25C Corsa to mount?
It was definitely easier than the 23C. However, I found that once I was careful to keep both beads in the center groove (of Hed and Enve wheels at least), mounting became vastly easier with all these tires. I was able to mount the CS Pista with no tools at all; the CS 25C only required a little lever use at the end.
for the 23c on Reynolds Strike SLG, keeping the bead in the channel and same as above only need a lever at the end.
I got a puncture this past weekend from some glass. It was the same size glass I have pulled out of GP4k, for what its worth.