[Closed] How much quicker are narrow tyres?

Shitloads!

Just try it over 20 miles & never ask again.

1.5s should do you for road.

There is a piece of research that shows wider lower pressure tyres to have less rolling resistance.

It doesn't cover all conditions and certainly is counter-intuitive but is the only decent research I have seen on this

23mm is where it's at (provided your not running 24mm rims of course)

spacemonkey - Member
I've never been into 1.8's etc, especially for off-road stuff, so when I recently decided on some road rubber I went for Schwalbe Big Apple 2.0's.

I have just built a bike with 2.35 Big Apples.

The other day I was freewheeling down a hill and caught up with other cyclists also freewheeling down despite there being originally a big gap.

So now I'm a believer in fat tyres. Don't think they would be a good idea for a TT though 🙂

Ok, so are we talking 20-30% quicker with say 1.5's?

There is a piece of research that shows wider lower pressure tyres to have less rolling resistance.

No advantage to pumping tyres up too hard for road use, given typical UK road surfaces, but narrower than 2.0" should certainly be quicker.

Try super motos next time epicyclo, even faster 😀
2.3s do mean you don't have to worry about road surface

Aracer - Missed that ( road use) Doh!

Yeah, that's a weird piece of research TJ - like you say, it sounds counter-intuitive at best. I've always run something like 40psi off-road (in good, grippy, dry conditions) and lowered it for wet/slippery stuff. And never really been bothered. It's just that now I'm doing some road training I want to find ways to cover greater distances more easily. Currently running 2.0's at 70psi.

it makes sense. Pneumatic tyres work by stopping the moving object having to work against gravity to rise over bums in a surface. When your bumps are on a large scale, e.g. a rocky trail surface, you need a lot of "give" in the tyre to squash enough to avoid working against gravity, hence low pressure/high volume.

It seems "counter intuitive" because on-road , where rolling resistance is more significant, it feels like that. In this case the bumps are a lot smaller and you need a lot less movement in the tyre to iron out the bumps. However in this case, there are other significant effects such as shear wich are not that well understood, and make the rolling resistance lower when it's wet. There was some research on road bikes which said you want the tyre to sag 15% when you sit on the bike, and that's the best balance between low contact area reducing friction and enough give to get over bumps. I suspect this does depend on the surface though.

That could all be rubbish but is said with confidence (that must count for something?), and there is research to back most of it up....

You cover the reason why lower pressure rolls better off-road quite nicely, captaindanger. The reason for high pressure on road though is that the rolling resistance on a smooth surface is mostly due to energy loss in the tyre due to continuous deformation, since rubber has quite a high hysteresis (ie when you flex it it absorbs energy rather than being perfectly elastic). What a lot of road riders miss is that if you're riding on a typical UK road surface it isn't perfectly smooth - even newly laid stuff is often quite coarse. Hence it doesn't pay to use too high a pressure on road either to avoid the energy losses due to bouncing the whole bike - I used to run 140psi for time trialling with 20mm tyres, but dropped that to ~120.

You lot haven't been on my commute, some of the roads are like Alp d'Huez

I think that research doesn't cover all situations - soft ground / mud / higher speeds.

still - very thought provoking

captaindanger - it makes sense. Pneumatic tyres work by stopping the moving object having to work against gravity to rise over bums in a surface.

I have just built a bike with 2.35 Big Apples.

The other day I was freewheeling down a hill and caught up with other cyclists also freewheeling down despite there being originally a big gap.

ooOOoo - Member
Try super motos next time epicyclo, even faster

Have one on order for the back, the front is a 29er wheel. 🙂

I vaguely remember from back in the days of the early Moultons that one of the significant factors is the TPI of the tyre. The more TPI, the more supple the tyre, and hence the faster it is.

Schwalbe are one of the leading exponents of balloon tyres [b][u][url= http://www.schwalbe.com/gbl/en/startseite/?gesamt=53&flash=1&ID_Land=38&ID_Sprache=2&ID_Seite=126 ]and have this to say about it.[/url][/u][/b]

I think it can be summed up by saying that on real-life road surfaces a fat supple tyre is claimed to be faster than a thin tyre when pressures are the same - right up to the point where aerodynamics becomes important

I use 1.5 slicks on my commuter, been doing 1 fullride in on the mtb off-road and then returning on my normal road train route. the difference in the tyres is ridiculous so I am guessing there will be a notable difference between 2" and 1.5.

could that mean you and bike are carrying a bit more weight and gravity is giving you a helping hand

Galileo covered that one back in the sixteenth century!

Dropped a hollow cannonball and a solid one; both hit the ground at the same time.

(EDIT: according to Wikipedia it was a thought experiment and he didn't actually do it).

Fat tyres are heavier usually so more energy needed to get them going. It's not necessarily the time that changes, it seems to be the effort required.

page 15

"Why do Pros ride narrow tires if wide
tires roll better?
Wide tires only roll better at the same inflation pressure,
but narrow tires can be inflated to higher pressures than
wide tires. However, they then obviously give a less
comfortable ride.
In addition to this, narrow tires have an advantage over
wide ones at higher speeds, as they provide less air
resistance.
Above all, a bicycle with narrow tires is much easier to
accelerate because the rotating mass of the wheels is
lower and the bicycle is much more agile.
At constant speeds of around 20 km/h, the ride is better
with wider tires. In practice, the energy saving is even
greater than in theory as the elasticity of the tires
absorbs road shocks, which would otherwise be transferred
to the rider and so saves energy."

I found its not just width, 'suppleness' also makes a difference. Some Spesh All Condition Pro's were 1-2mph faster than some heavily punctured proofed continentnals of a similar width and pressure.

The specialized tyres did fall to peices though!

Luked2 - however Galileos experiment only applies in a vacuum - in the real world with air resistance heavier tends to be faster downhill - as the force produced by the mass pushing them down the hill increases more than the air resistance as people get fatter.

Ok, so are we talking 20-30% quicker with say 1.5's?

Thats a huge dfference so no. I think thats montain bike with offroad tyres to time trial bike stuff

Ok, so are we talking 20-30% quicker with say 1.5's?

Thats a huge dfference so no. I think thats montain bike with offroad tyres to time trial bike stuff

I'm pretty sure my 2.0 Big Apples are about 15% quicker than my Fire XC 2.1's because of recorded lap times on a couple of road circuits I've done lately. Identical fitness, etc.

Hence wondering if 1.5's will make an additional few percentages ...

I went from 2.1s to 1.8s (on the MTB - do some road riding on my MTB shockingly) and find the 1.8s sooo much quicker.

But now they've stopped making them (Sauserwinds) so got an NN 1.8 Evo ready to fit when my part worn rear tyre finally becomes a slick (almost there).

Clearly road tyres (23cc on mine) inflated to 110PSI are quicker but the difference isn't as huge as I had expected. I do run my MTB tyres at 50-60PSI though.

Have a look at Conti Grand Prix 1 1/8 folding, just check yer rims take tyres as narrow as 1" (mavic 717 do).

They make so much difference, riding a mtb on the road is so much faster it's almost fun.

Err, isn't the tread quite different on those? I thought the Apple was nearly a slick, whereas the Fire XC is a tyical MTB tyre. That would have a much bigger difference than the width in that instance, I imagine.