[Closed] Rolling Resistane - low pressure with fat tyres study

Do you have a link to the original study? Or was it actually published on mtbr?

How about a summary for those of us too lazy to register at mtbr? 😛

[url= http://www.bernhansen.com/Tester/Dekktrykk,%20bredde%20og%20knastens%20innvirkning%20-%20schwalbe.pdf ]This one?[/url]

You'll find a link on Schwalbe's site if you can't be bothered to register.

Interesting piece of research but does not cover all situations. Nothing about higher speeds or softness of the ground - both variables that could alter the result

richmars - Member

This one?

yep

TJ - do you think those variables would change the results much?

bonesetter - who knows? There are other variables as well not tested.

Softness not covered? Eh?

speed? Do you wish he'd gone slower? 😀

Al - there is a difference in rolling resistance with hard and soft ground and this is different to what they tested. Does the effect thewy measured work with soft ground?

speed - higher speeds than they tested. Does the effect they found exist at higher speeds?

I don't know the answers to this but that is two sets of parameters they did not test. Soft and hard ground is not the same as grass or gravel

well that was interesting,, it goes against almost everything i thought,,
i did used to run 1.5 conti cross country tyres a lot,,

but what it doesnt say is that big tyres with low tyre pressures can feel very strange while changing direction and cornering ,,

I think speed may multiply the rolling resistance ,, if aero drag increases with speed squared , double speed 4 times more drag

would have been interesting to do the tests at three different speeds

That's not what I'd expected. I can't run 1.5 bar in a 2.3 tyre though. It's like trying to ride a trifle. Maybe I'll experiment with some bigger sizes.

The article also says the lighter tyres were weighted to counteract the variable

"It's like trying to ride a trifle"

Yeah theres a pressure below which where the tyre is not properly supported. It squirms around corners and threatens to roll off.

I don't know the answers to this but that is two sets of parameters they did not test. Soft and hard ground is not the same as grass or gravel

It's the same enough for me...in any case WGAS about rolling resistance on "soft ground" - you're riding slow as anyway.

How would speed affect RR then? Not much/if at all is my thinking.

i'm sure speed effects RR ,, if you just think how tyre noise increases with speed

chuckles at the idea of riding an underinflated semi-slick round these parts 😀

cool research though, will def deflate the tyres a bit next time out

huckles at the idea of riding an underinflated semi-slick round these parts

How come all these jeyboy racers aren't on big fat tyres?

Perhaps they should be?

S'not cool in the scene, innit. Just like skinsuits are not the done thing for DH. UCI will be banning them next.

Or it's flawed. I know that big fat tyres certainly feel harder work no matter how many times I run that theory through my head. Could be the weight though.

in any case WGAS about rolling resistance on "soft ground"

That study is nothing new BTW - just that like most counter-intuitive findings most people either won't believe it or ignore it. I've certainly been using wider tyres at lower pressures for the racing I do for several years - still find it very hard to convince those who race on teams with me to get away from the traditional narrow tyres pumped up hard.

Of course when I say wider tyres I'm only talking full size 2" ones rather than anything bigger - but then we all used to go round on 1.8s or less. I might go bigger, but don't have the clearance on the back (I suppose I could go bigger just on the front, but given most RR is from the rear tyre it seems more trouble than it's worth). I don't normally run super low pressures either, but given a lot of the distance I cover in races is on tarmac I have to find a compromise between low and high pressure - which is also a reason not to go too wide.

Or it's flawed. I know that big fat tyres certainly feel harder work no matter how many times I run that theory through my head. Could be the weight though.

[url= http://www.singletrackworld.com/forum/topic/wider-tyres-are-faster ]http://www.singletrackworld.com/forum/topic/wider-tyres-are-faster[/url]

my point was that races are on firm trails IME - which do get muddy, if that's whatyou mean.

2.4 RRs for racing here, not that I do much.

This is old news isn't it? I remember something on this years ago. Long enough for me to have dropped to about 30 psi for most situations. TJ high speed omitted from the tet to exclude an aero advantage, says so in the introduction