Tyre rolling resistance and its translation into riding....?

[E65Ross]

Hi guys,

I've just a quick, probably a very simple, question. There's a website "bicyclerollingresistance" which measures the rolling resistance for all sorts of tyres at various PSI and gives a rating in watts. It says the load of 42.5kgs (assuming a rider of 85kgs, I guess) and the speed is 18mph.

If, for example, 1 tyre at a given PSI gives 12W rolling resistance, yet another gives 20W rolling resistance, does that mean that to go 18mph on the 20W tyre I'd need to put in 16W more (assuming I weighed 85kgs, of course!)? Or does it work differently?

Cheers

[lufbramatt]

Are the numbers for both wheels together or a single wheel?

But yes I would imagine higher rolling resistance needs more power for the same sped assuming everything else stays the same.

[E65Ross]

lufbramatt said:

Are the numbers for both wheels together or a single wheel?

But yes I would imagine higher rolling resistance needs more power for the same sped assuming everything else stays the same.

They are numbers for 1 wheel only. I was just interested in knowing if the "watts" for rolling resistance means that they are the additional power you'd need to put in to reach the same speed, or whether it doesn't quite work that way.

Cheers

[Magic919]

It’s a very simplistic and narrow test that will not necessarily translate into exact results on the road. The 42.5 is half the notional load which would include the bike and anything else carried.

[Kawasicki]

E65Ross said:

Hi guys,

I've just a quick, probably a very simple, question. There's a website "bicyclerollingresistance" which measures the rolling resistance for all sorts of tyres at various PSI and gives a rating in watts. It says the load of 42.5kgs (assuming a rider of 85kgs, I guess) and the speed is 18mph.

If, for example, 1 tyre at a given PSI gives 12W rolling resistance, yet another gives 20W rolling resistance, does that mean that to go 18mph on the 20W tyre I'd need to put in 16W more (assuming I weighed 85kgs, of course!)? Or does it work differently?

Cheers

I think you are correct. Though the load distribution on a bike is not usually 50/50.