Difficulty in tire changing

Thanks for those numbers...

This is a huge range of Crr... and it has a big effect on speed.

Crr= Prr/(W*V) = Prr/ (85kg*9.81m*35km/hr*.2778) = Prr*.0001233

Tire Prr Crr Speed*
Vittoria Open Corsa Evo CX 27.1 W .00334 23.22
Michelin Pro2 Race 29.2 W .00360 23.14
Michelin Carbon 34.7 W .00428 22.94
Panaracer Stradius Pro 35.4 W .00436 22.91
Hutchinson Fusion 39.6 W .00488 22.76
Continental Ultra GatorSkin 40.3 W .00497 22.73
Continental Grand Prix 3000 46.6 W .00575 22.50

*
185lb rider + bike
250W rider output
CdA = .32m^2 (racing crouch, normal road bike)
Transmission efficiency = 96%

So... they tested these in a lab, on a big drum? Continental must be
very unhappy about this...

The numbers I got on rollers for the Cx, & pro race 2 pretty much
match these. No surprise on the GP3000 either. The ultra-thin
"race only" Conti Supersonic was one of the slowest tires I tested.

BTW, the Veloflex master (clincher) was slow too.


-jens

Ron Ruff wrote:

So... they tested these in a lab, on a big drum? Continental must be
very unhappy about this...

Yes, the tyres were tested on what looks like a steel drum. The wheel
and inner tube were the same for all tyres and the pressure always 7.0
bar. The equipment was actually Continental's so the result probably
didn't come as a surprise to them.

Of course their tyres also had strong points like excellent puncture
resistance and a combination of low weight and good mileage. They just
aren't very fast. I don't know if it's an exaggeration to say that they
are not suitable for competition.

The rolling friction coefficients in your post were a bit off, but here
are all coefficients from the mag, lowest first. All tyres were
foldable 23-mm clinchers.

Deda Tre Giro d'Italia 0.0038
Vittoria Open Corsa Evo CX 0.0039
Michelin Pro 2 Race 0.0042
Vittoria Diamante Pro Rain 0.0044
Michelin Megamium 2 0.0047
Pariba Revolution 0.0048
Michelin Carbon 0.0050
Panaracer Stradius Pro 0.0051
Schwalbe Stelvio Plus 0.0052
Schwalbe Stelvio Evolution Front 0.0056
Continental GP Force (rear specific) 0.0057
Hutchinson Fusion 0.0057
Schwalbe Stelvio Evolution Rear 0.0057
Continental Ultra GatorSkin 0.0058
Ritchey Pro Race Slick WCS 0.0058
Schwalbe Stelvio 0.0059
Specialized S-Works Mondo 0.0061
Continental GP 3000 0.0067
Hutchinson Top Speed 0.0069
Continental GP Attack (front specific) 0.0073

The test also included a calculation that on a flat 40 km time trial, a
rider with a 300 W power output would finish 2 minutes and 18 seconds
faster with the Deda Tre tyres than with Hutchinson Top Speed.

-as

Antti Salonen wrote:
The rolling friction coefficients in your post were a bit off

Ah! The problem is that I put 35 rather than 30 in the equation. This
is how it should have read:

Crr= Prr/(W*V) = Prr/ (85kg*9.81m*30km/hr*.2778) = Prr*.0001233

But, with the Crr values there is no need to convert. Here is the speed
and differentials for all of the tires:


Tire Crr Speed* Delta

Deda Tre Giro d'Italia 0.0038 23.08
Vittoria Open Corsa Evo CX 0.0039 23.05 0.03
Michelin Pro 2 Race 0.0042 22.96 0.12
Vittoria Diamante Pro Rain 0.0044 22.90 0.18
Michelin Megamium 2 0.0047 22.81 0.27
Pariba Revolution 0.0048 22.78 0.30
Michelin Carbon 0.0050 22.72 0.36
Panaracer Stradius Pro 0.0051 22.69 0.39
Schwalbe Stelvio Plus 0.0052 22.66 0.42
Schwalbe Stelvio Evolution Front 0.0056 22.54 0.54
Continental GP Force (rear) 0.0057 22.51 0.57
Hutchinson Fusion 0.0057 22.51 0.57
Schwalbe Stelvio Evolution Rear 0.0057 22.51 0.57
Continental Ultra GatorSkin 0.0058 22.48 0.60
Ritchey Pro Race Slick WCS 0.0058 22.48 0.60
Schwalbe Stelvio 0.0059 22.45 0.63
Specialized S-Works Mondo 0.0061 22.39 0.69
Continental GP 3000 0.0067 22.21 0.87
Hutchinson Top Speed 0.0069 22.15 0.93
Continental GP Attack (front) 0.0073 22.04 1.04


*
in MPH
185lb rider + bike
250W rider output
CdA = .32m^2 (racing crouch, normal road bike)
Transmission efficiency = 96%

On 1 Nov 2005 18:29:47 GMT, Antti Salonen
wrote:

Vittoria Open Corsa Evo CX 27.1 W
Michelin Pro2 Race 29.2 W
Michelin Carbon 34.7 W
Panaracer Stradius Pro 35.4 W
Hutchinson Fusion 39.6 W
Continental Ultra GatorSkin 40.3 W
Continental Grand Prix 3000 46.6 W


Any Schwalbe tires in the test?

JT

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