just a wee question to find out as to whether i can change the rolling resistance of my tyres by turning them round,
i was out on friday with my mate and as we had to use canal path to get home from our off-road ride the path is tarred and when we free-wheeled down a hill i noticed i slowed up and stopped quicker than him,
im running 2.3 spesh armadillo’s and he’s running panaracer fire xc pro’s 2.1,

Doubt it would be material, there are always many other factors too, weight, aerodynamics, bearing/freewheel friction maybe.

Higher pressures, higher quality, xc or semis slick tyres may help (on the road) – AFAIK armadillos have puncture protection that makes them roll poorly.

maybe, my kenda nevegals have arrows indictating correct direction, more likely due to rubber compound and air pressure and your own weight.

too many variables between people and bikes in terms of friction in other compenents, rider weight etc.

fit different tyres on same bike and do repeated tests for rolling down the same hill.

it is astonishing how much quicker a similar weight rider can freewheel down a modest tarmac’ed hill, sat right up for wind resistance. I don’t have my tires over 30-35psi and use 2.1 nobby nic on the front and 2.1 sb8 on the back. Not a particularly racey combination i’d have thought. 😕

Does this fab difference in rolling resistance make me faster uphill too?

I don’t think that weight effects rolling resistance though (or does it?) it just takes more energy to spin them up to speed and they lose speed less readily, I wouldn’t have thought it would have made much, if any, difference freewheeling down a hill. Isn’t rolling resistance about how efficient a tyre is? There’s lots of clever stuff at I don’t understand at en.wikipedia.org/wiki/Rolling_resistance.

In my experience tread and the rubber compound make more of a difference than weight. I’ve ridden heavier tyres that felt easier to ride on road that lighter tyres with knobs. I’d imagine that a tackier compound would make a big difference too.

What tyres are you running? Armadillo is, AFAIK, a puncture protection technology applied to a variety of tyres. In any event I can’t see that turning them around would make much difference.

julianwilson – Member
Does this fab difference in rolling resistance make me faster uphill too?

Everywhere.

PJay is correct in that weight in itself does not affect RR, but heavier tyres tend to be thicker, cheaper etc and so will roll more slowly.

Q: what affects RR more: do wider tyres roll beter (all other things remaining equal?)

best thing for RR is avery small contact patch (ie. narrow tyres at high pressure).

I thought a heavier rider will build up more momentum on hill so might roll further once they get to a flat bit?

A.F.I.A.K it has a lot less to do with width of a tyre, and more to do with how easily the tyre carcass deforms/changes shape/recovers at the point of contact, as it rolls along. Someone will be along in a minute with the link to the study that schwalbe did a while ago, all about it.

Wwaswas yes, but Remember lower pressures off road can roll faster.

A wider tyre will roll slightly faster.

The swalbe study while interesting and the only real data I have seen on this is very limited to draw any conclusions from – only low speed and climbing.

You have to control variables obviously but that study cannot be extrapolated to other situations

thanks for the input guys,i dont have any other tyres to compare to but i was thinking of ordering some if the armadillo’s were to slow,not that i ride alot of tarmac,i tend to go off-road most off the time,either trail centre’s or xc up my local hills as theres loads of riding to be done,grassy,boggy and some gravel roads.
intersting thought about the whells though as a while ago my cones were slack and i tightened them.could i have tightened them to much??might need to take wheels of and take them for service unless its do-able at home,its shimano 545 hubs i think,never had a go b4 but willing to try,
cheers craig

If the ramped side of the treadblocks hit the ground first then the tyre will always roll faster than if the square edges do – for tyres marked ->F and <-R it’s the F direction.

A tyre of the right width to get the optimum contact patch shape for a given pressure and load will roll fastest. The heavier the rider and/or lower the pressure, the wider the tyre needs to be for the lowest rolling resistance.

The Schwalbe study pointed at the knobs. With tall, spaced central tread the wheel is continually descending and climbing the knobs which uses your kinetic energy. Lower, close packed knobs do this less.

That’s why this tyre rolls so well for such a big knobbly tyre. From the ground’s perspective the centre knobs are almost continuous.

various rolling resistances measured here – http://endless-sphere.com/forums/viewtopic.php?f=3&t=16599

Schwalbe test PDF

bobgarrod – interesting data.