Spinz

Will a narrower tire roll faster than a slightly wider one? Wisdom says yes but I'm thinking in terms of 700cx20 or 23 vs 700cx25 -----. Lp

rhenning

Not enough that you would know the difference unless you ride at Lance's level. Roger

lmzimmer

Not enough that you would know the difference
+1
Also there is often more difference from one brand of tires than in different sizes. Some larger diameter tires - 28 or 30 have actually scored less rolling resitance in testing than narrower sizes.

ricohman

I have some 23's that are as big as some of my 25's.
I would think at max pressure you would never notice the difference.

Road Fan

Controversial - conventional knowledge and some engineering testing says there's less rolling resistance with a narrow hard tire when tested on a drum. Some more recent coast-down tests involving bikes on pavement do not agree. There's been some research trying to identify the causes of energy loss in a rolling bike tire, but I haven't heard of any analysis that would show definitively why one conclusion is right and the other wrong. I know from my experience with engineering testing that the test must be designed to represent the usage condition you care about. At the same time the methodology must be sound for the results to be a valid representation of user or customer practice. Any test design can be ruined by poor methodology.

Wider tires add frontal area which adds to aerodynamic drag. If there's some truth to wider being more efficient, there's certainly a width where the improvement trend levels out. The rim shape would also come into play here, considering effect of airflow around the tire/rim combination.

The Bosch automotive handbook estimates the relative effect of wheel rolling resistance, bearing friction, and air drag in level travel. Tire-based resistance is very small compared to air resistance at any non-beginner cruising speed, and bearing friction is even less. It would not matter for rides that do not tax your limits. When you reach your limits in terms of speed or distance, having that little extra margin could be significant. A half-percent improvement over a double century is a mile. Is that significant? Well it could be at the end of the event!

My 2 cents, sorry it couldn't be simpler.

Road Fan

MIN 

I think the bigger issue here is weight as it relates to climbing and accelerating. I don't notice to the tire resistance from size to size while cruising but it take more effort to accelerate and climb on a bigger tire.

MKahrl

The roll down tests done of pavement indicated that tire width had very little to do with rolling resistence. The construction of the tire had a much greater affect. Until recently only very narrow tires had high quality construction but now there are some very nice tires being made in widths of 28, 32, 35 and 40mm that are also fast.

Very narrow tires pumped up to very high pressures do feel faster, even when they're not, so if you just like the feeling of going fast then by all means go narrow.

Mooo

Phew, you're only discussing width. I thought it was going to be about diameter, and sadly, all the really fast bikes use small wheels.

As for width... I've never ridden much on steel drums so I'm a poor one to ask, but have a strong suspicion that anything under 28mm is counter productive unless you're doing it for money.

Pompiere

The quality of the tire will make a difference too. A cheap narrow tire may not roll as well as a better quality, wider tire, due to the difference in construction and/or materials.

graywolf

In theory, everything else being the same, yes. However, everything else is usually not the same. Also note that even if you are talking about the same brand and rubber batch that beyond a certain weight point the rolliing resistance goes up. In other words a 200# rider would probably find a 25mm tire faster than a 20mm one. That seems counter intuitive until you think about it a bit. The contact patch is a flat spot against the road. So a short wide patch is faster than a long narrow one, however with a lighter rider you get a short wide patch v. a short narrow one so the narrower tire is faster.

Nothing is as simple as it seems at first glance.

Longfemur

Well, try it for yourself. Buy a few pairs of tires and try them. Don't rely on other people's rationalizations. You get less and less improvement as you get down to very narrow widths, but a tire in the 23-25 mm range on a fine road bike will feel a lot snappier than a 32-35 mm touring tire. It may not be any faster in an absolute sense, but I think that you will find it take less effort to maintain a speed on a good road racing tire. But you are welcome to prove me wrong by trying different widths for yourself.

gnome

I'd say it would depend on the road surface that you ride on. Typically a narrower tyre needs a higher pressure than a wider tyre. Tyre construction is more important than the width, as other posters have stated.

I've found that the two biggest issues regarding tyre pressure and the road surface. On a rough or poor surface as in our usual country chip-sealed roads that sets up lots of vibrations. I've found that I am actually faster with wider tyres at a lower pressure than narrow tyres at very high pressure, as I am not getting shaken to pieces. On a nice smooth surface a narrow high pressure tyre is faster.

I'll admit that my fastest bike is the Mercian with 27 x 1" tyres, but the second fastest is my Rocket with 20 x 1.5 tyres. The Mercian is not designed to go slow, so I don't when I ride it.