[PHXC700SP]

The other day I replaced my stock tires on my trek 2100 which were bontrager race lite 700x25c to Michelin Pro Race 700x23c and My first ride on the new tires on a 26 mile route that I ride regularly turned out to be my fastest time to date on that route here's the numbers on my old tires: Avg speed 15,max speed 35.3, time-1.44.11 then on my new tires first ride : Avg speed-16.8mph,max speed-36.5mph,time-1.33.49 shaving nearly 11 minutes off my avg time!!!! So I am in awe and refuse to believe that tires can make that big a difference so I go for a 26 mile ride today same route similar weather avg speed-16.5mph, max speed-36mph,time-1.35.33 nearly identical to my previous days ride it's gotta be the tires. I just thought that was interesting and figured I would share it.

PHX

 

[Squint]

The Pro Race 2 has one of the lowest coefficients of rolling resistance. If you go from a tire that has a poor Crr to a fast tire, the difference can be quantifiable.

 

[Kerry Irons]

Gotta call BS

The Pro Race 2 has one of the lowest coefficients of rolling resistance. If you go from a tire that has a poor Crr to a fast tire, the difference can be quantifiable.

Quantifiable and 1.5 mph are completely different things. I've never heard of credible data that suggests that tires (in the same performance category) can give even 0.1 mph.

 

[tobu]

i suppose on a technical course better tires could easily make a 1-1.5mph difference if they inspired more confidence and better cornering. But that would have to be an awfully technical course where you are constantly pushing the limits the whole time -- not really a typical training loop.

 

[teddysaur]

Did you update the speedometer from 25c to 23c?

 

[Dave Hickey]

That was my thought too. I don't think it will make a 1.5mph difference but it will give false readings...

 

[rruff]

B.s.^2

Quantifiable and 1.5 mph are completely different things. I've never heard of credible data that suggests that tires (in the same performance category) can give even 0.1 mph.

It isn't likely that 1.5 mph is due to different tires... but it could be a *lot* more than 0.1 mph!

Here is some data from an Oct-2005 test done by Tour. The last number
is the difference in speed relative to the best tire. There is a 1 mph spread between the fastest and slowest tire.

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%

 

[boon]

I've had similar experience with the OP. the standard stock tyres on my bike was specialized mondo. after three punctures, all within one month, i decided to switch to kenda kaliente. there was a noticeable drop in my average speed. on one of my standard routes, my average speed dropped from 25.2km/h to 24.5km/h. in fact, the first day i had them on, i could actually feel that i had to exert more energy to maintain a respectable pace, which proved to be quite tiring after a while.

after a while, then i decided to switch to michelin pro2 race, primarily for longer rides, and there was a noticeable difference. the michelins rolled a lot better and felt more effortless.

recently, i upgraded my wheelset - campy protons with michelin pro2 race. the kenda went back on the stock wheelset alex AT400. on one of my longer training route, the AT400/kenda combo had an average speed of 24.8km/h. the protons/michelin on the same route was 25.7km/h. yes, i accept that the protons are a significant step up from the AT400 but i would maintain the view that tyres do make a difference in my experience. disagree if you like. we each have different experiences and this is just my experience.

boon

 

[PHXC700SP]

Did you update the speedometer from 25c to 23c?

Thanks everyone for raining on my parade and bringing me back to earth, and thankyou for reminding me to update the tire size on my computer. I am sure that that is part of it and when I am able to ride that route probably tomorrow with the updated info in my computer I will repost , I will also set my stopwatch as well so I can verify the data and see if there was in fact an improvement. I do see that the mileage was slightly off from the tire change without updating the computer, on the old tires the distance was 26.18 miles and after the tire change the distance was 26.33 miles, I will post an update after my next ride. And to those of you that could only reply that it was BS, well I did not, nor would I post, anything intentionally misleading or false. And thankyou to those of you who put some thought into what could have effected my computers readings.

thanks teddysaur,
PHX

 

[Spunout]

Control: Are you in the same fitness now? Same wind? Weather?

BS. I know you didn't do it on purpose. Nobody would be able to tell a difference unless on a power meter in a lab environment. And then, I'd get a machine to turn the pedals instead of a human.

 

[botto]

Did you update the speedometer from 25c to 23c?

my thoughts as well, but it doesn't explain the 11 minute improvement.

 

[baylorboy]

Could someone please explain what rolling resistance is? In all my engineering classes, we only spoke of friction, both static and kinetic. Rolling resistance is a phrase that gets thrown around alot, but no one has given me a real definition of it. What is the "coefficient of rolling resistance" and how is it measured? Thanks

TB

 

[Mark McM]

Time to face facts

Thanks everyone for raining on my parade and bringing me back to earth, and thankyou for reminding me to update the tire size on my computer.

I'm afraid that it is time to face facts, and just admit that it is you who have gotten stronger and faster, and not your tires. Yes, I know that you must be far to humble to claim credit for the speed improvement yourself, instead of heaping praise on an inanimate object, but I think the fact speak clearly by themselves.

So, I guess this begs the question - why are people so willing to credit their equipment purchases with performance improvements, rather than accepting that it is they themselves that have improved? Afterall, doesn't the rider provide most of the weight, most of the drag, most of the control, and all of the power? Large changes in performance are therefore likely due to the rider, not the equipment - so why do so many riders ascribe so much of their performance improvements to their equipment?

 

[Dr. Paul Proteus]

Could someone please explain what rolling resistance is? In all my engineering classes, we only spoke of friction, both static and kinetic. Rolling resistance is a phrase that gets thrown around alot, but no one has given me a real definition of it. What is the "coefficient of rolling resistance" and how is it measured? Thanks

TB

The coefficient of rolling resitance is a dimensionless parameter describing the retarding force of rolling divided by the weight of a rider.

Generally speaking, for a moving wheeled vechicle on flat ground, you can separate the forces causing it to slow into two catagories; aerodynamic drag which is proportional to v^2, and rolling resistance which generally varies linearly with velocity. On a bicycle, rolling resistance is dominated by parasitic losses within the tire itself (caused by the constant deformation of the tire). For this reason, rolling resistance is essentially treated as coulomb friction even though there is a small viscous fricitonal component to it.

 

[Spunout]

- so why do so many riders ascribe so much of their performance improvements to their equipment?

Because it is easier to spend money on equipment than it is to commit to training. When the next performance plateau is reached, OP will look for new equipment as it is an easier fix than changing or improving training techniques.

Otherwise, in the relatively untrained who don't quantify fitness progression (regular testing) it seems to be the equipment making the difference.

 

[Mark McM]

Coefficient of rolling resistance

Could someone please explain what rolling resistance is? In all my engineering classes, we only spoke of friction, both static and kinetic. Rolling resistance is a phrase that gets thrown around alot, but no one has given me a real definition of it. What is the "coefficient of rolling resistance" and how is it measured?

If you go back to your engineering text books, you'll probably find some information "hysteresis damping" or "hysteresis losses".

For a simple description, when a tire rolls, the tread and casing deform at the ground contact point, flattening out a bit at the ground. The flexing of the tread and casing is mostly elastic, but a small amount of the energy to deform it is absorbed as heat energy. This energy is not returned when the tread and casing leave the ground contact point, and is instead dissapated as heat. For bicycle tires, these losses are very small, but still very real.

The coefficient of rolling resistance corresponds similarly to the coefficient of friction, in that it describes the force/energy dissipated by the rolling of the tire over a distance, and is proportional to the normal force on the tire - the normal force is generally the weight supported by the tire:

Frr = Crr x Fn = Crr x M x g

Frr = Rolling resistance force
Crr = Coefficient of rolling reistance
M = Mass supported by the tire
g = Acceleration of gravity.

The coefficient of rolling resistances of narrow high pressure bicycle tires is typically in the range of 0.003 - 0.007. The coefficient can seem very small, but it can add up to significant losses at racing speeds. For example if a bicycle/rider with a mass of 80 kg (176.4 lb) rolls at 11 m/s (24.6 mph) on tires with a Crr of 0.005, the power losses due to the rolling resistance is:

Prr = Frr x V = Crr x M x g x V = (0.005) x (80 kg) x (9.806 m/s) x (11 m/s^2) = 43 Watts

 

[jgsjr]

The other day I replaced my stock tires on my trek 2100 which were bontrager race lite 700x25c to Michelin Pro Race 700x23c and My first ride on the new tires on a 26 mile route that I ride regularly turned out to be my fastest time to date on that route here's the numbers on my old tires: Avg speed 15,max speed 35.3, time-1.44.11 then on my new tires first ride : Avg speed-16.8mph,max speed-36.5mph,time-1.33.49 shaving nearly 11 minutes off my avg time!!!! So I am in awe and refuse to believe that tires can make that big a difference so I go for a 26 mile ride today same route similar weather avg speed-16.5mph, max speed-36mph,time-1.35.33 nearly identical to my previous days ride it's gotta be the tires. I just thought that was interesting and figured I would share it.

PHX

Did you reset your cycle computer for the newer (smaller diameter tires)?

 

[Uprwstsdr]

What about tire pressure?

 

[alienator]

I'll call BS on that....

I'm afraid that it is time to face facts, and just admit that it is you who have gotten stronger and faster, and not your tires. Yes, I know that you must be far to humble to claim credit for the speed improvement yourself, instead of heaping praise on an inanimate object, but I think the fact speak clearly by themselves.

So, I guess this begs the question - why are people so willing to credit their equipment purchases with performance improvements, rather than accepting that it is they themselves that have improved? Afterall, doesn't the rider provide most of the weight, most of the drag, most of the control, and all of the power? Large changes in performance are therefore likely due to the rider, not the equipment - so why do so many riders ascribe so much of their performance improvements to their equipment?

Yeah, whatever. Then how come when I made the upgrade below to my bike, my average speeds went WAY up?

 

[ergott]

If you go back to your engineering text books, you'll probably find some information "hysteresis damping" or "hysteresis losses".

For a simple description, when a tire rolls, the tread and casing deform at the ground contact point, flattening out a bit at the ground. The flexing of the tread and casing is mostly elastic, but a small amount of the energy to deform it is absorbed as heat energy. This energy is not returned when the tread and casing leave the ground contact point, and is instead dissapated as heat. For bicycle tires, these losses are very small, but still very real.

The coefficient of rolling resistance corresponds similarly to the coefficient of friction, in that it describes the force/energy dissipated by the rolling of the tire over a distance, and is proportional to the normal force on the tire - the normal force is generally the weight supported by the tire:

Frr = Crr x Fn = Crr x M x g

Frr = Rolling resistance force
Crr = Coefficient of rolling reistance
M = Mass supported by the tire
g = Acceleration of gravity.

The coefficient of rolling resistances of narrow high pressure bicycle tires is typically in the range of 0.003 - 0.007. The coefficient can seem very small, but it can add up to significant losses at racing speeds. For example if a bicycle/rider with a mass of 80 kg (176.4 lb) rolls at 11 m/s (24.6 mph) on tires with a Crr of 0.005, the power losses due to the rolling resistance is:

Prr = Frr x V = Crr x M x g x V = (0.005) x (80 kg) x (9.806 m/s) x (11 m/s^2) = 43 Watts

Thank you for a great explanation.

-Eric