25mm tyres and climbing

holker

Much debate on this forum about rolling advantages of 25mm tyres compared to 23mm. What happens on long steeper climbs when road speed much reduced? Wider tyres mean more tread on the road does this make climbing with wider tyres more difficult?

P_Tucker

Well, they've heavier, but unless you're racing up alpine cols what real difference would it make?

luv2ride

Get Continental Grand Prix 24mm Black Chilli tyres - excellent compromise!

balthazar

holker wrote:

Much debate on this forum about rolling advantages of 25mm tyres compared to 23mm. What happens on long steeper climbs when road speed much reduced? Wider tyres mean more tread on the road does this make climbing with wider tyres more difficult?

Lower RR is lower RR. Incline (and speed) doesn't matter. There are other considerations in tyre width (as discussed here often), but RR is hill-agnostic.

jibberjim

balthazar wrote:

Lower RR is lower RR. Incline (and speed) doesn't matter. There are other considerations in tyre width (as discussed here often), but RR is hill-agnostic.

And the lower speeds mean the likely aerodynamic penalty of the wider wheels is less of an issue, so it would be the other way from what the OP thinks.

nferrar

Weight would win out on hills so the smaller the tyre the better (even though I'm a believer in the reduced RR of 25's...)

thegreatdivide

Stanley222 wrote:

nferrar wrote:

Weight would win out on hills so the smaller the tyre the better (even though I'm a believer in the reduced RR of 25's...)

The weight difference is so small you would never notice the difference! :roll:
Unless you have 0% body fat then the biggest weight saving and difference to your ride would be losing weight from yourself!

+ 1

vorsprung

Some people think that the rotational weight of the wheel, including the tyre is important on climbs.

The rotational weight believers say that the weight of the wheel at the rim is crucial
This is because at a high rate of effort, often the pedal stroke is not as smooth as normal.
This means that within one wheel revolution the speed of the rim may accelerate or slow down. These small decelerations, go the theory, have to be fixed to keep the wheel moving at a constant rate. Extra power is needed to accelerate a larger mass. So lighter wheels work better with a ragged pedal stroke

The non believers say that the weight of the wheels only counts as part of the overall weight of the bike and rider. The wheel weight, they say is no more or less significant than the weight of (for instance) the seatpost on a climb.
This group claim that the accelerations and decelerations within a single rotation are not significant

I'm not sure about which actual theory is right. However, it seems to me that climbing with lighter wheels is easier, significantly more easy than the reduction to the overall weight would explain

Monty Dog

The difference is weight between a 23 and 25mm tyre of the same construction is going to be in the region of tens of grams and the impact on the aerodynamics of the wheel at those speeds almost neglible - by comparison, the weight loss from having a wee at the bottom of the climb would have more impact. On the converse, having a wider 25mm tyre for typically twisty, bumpy descent would mean you'd corner with more confidence and less likely to impact puncture, thus negating any perceived benefits accrued on the climb. Gimme the 25mm tyre anyday.

dilemna

thegreatdivide wrote:

Stanley222 wrote:

nferrar wrote:

Weight would win out on hills so the smaller the tyre the better (even though I'm a believer in the reduced RR of 25's...)

The weight difference is so small you would never notice the difference! :roll:
Unless you have 0% body fat then the biggest weight saving and difference to your ride would be losing weight from yourself!

+ 1

Yeah, cut out the pies is by far the best advice.

nferrar

Yeah but it's a theoretical discussion, I don't think anyone's actually suggesting it's worth changing from 25's to 23's just for a climb...

andrewjoseph

nferrar wrote:

Yeah but it's a theoretical discussion, I don't think anyone's actually suggesting it's worth changing from 25's to 23's just for a climb...

isn't that what contador did in the last two tours?

thiscocks

Luv2ride wrote:

Get Continental Grand Prix 24mm Black Chilli tyres - excellent compromise!

+1. Great all round tyre- comfortable and tough