Commuting Tyres

itboffin

Just went and had a look at some 28 & 32 tyres the spesh armadillos looked masshoof the bontrager & contis didn't :?

Doh!

vorsprung

UndercoverElephant wrote:

Actually, I thought that wider tyres had less rolling resistance at a given pressure than thin ones. The problem being, of course that thin tyres generally can take higher pressures than the thicker ones, making most of the above statement moot.

Edit: Knew I'd read this somewhere... http://www.schwalbetires.com/tech_info/ ... resistance

The speed of a tyre is a combination of rolling resistance, weight and aerodynamics

At commute speeds, aerodynamics can be discounted.

Rolling resistance is, as the chart says, generally a function of tyre pressure. But my experience is that narrower tyres at 100psi / 7 bar have a lower rolling resistance than wider ones...in general. If all factors were equal ie a GP4 23mm vs a GP4 28mm then it could well be that Schwalbe are right and the rolling resistance due to pressure is less on wide tyres. But usually narrow tyres have a better compound and are more flexible

The weight shouldn't be discounted either. With a tyre rotating at an absolutely constant velocity the weight makes no difference. Energy is only expended when accelerating a mass. Sure, there is drag to over come but this is mainly due to the tyre on the road (see above). There are 3 situations where wheel accelerations are of interest

1) Coming out of a corner. Not that common. Maybe 10 seconds in the hour?
2) Every pedal stroke. Unless your pedal stroke is 100% the same velocity for the whole rotation the wheel will suffer micro accellorations/ decellorations. Estimates vary on if this is a real big problem or a minor issue but it does happen, especially if you do not have a smooth pedalling style
3) Climbing hills. If there is a increase or decrease in the slope then it is difficult to maintain an absolutely steady speed. Additionally the extra power required may alter the smoothness of the pedal stroke

jedster

Vorsprung sounds german so he is bound to be right.

But I'm siding with UE on this one.

Quite so on both points. Vorsprung is trying to befuddle us with his faux-teutonic nomenclature - deforrm shape is better on wider tyres hence rolling resistance is lower at the same pressure (i.e., same comfort level).

I run 28mm ultra gators at 100psi. I seriously doubt whether they are slower than 23mm tyres in the real world (on my commute).

J

itboffin

I'm going to try my 32c conti CX tyres tomorrow should be interesting.

il_principe

From the Schwalbe site:

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.

Works for me. My commute is an endless case of accelerate/break repeat ad nauseam. So I'll take that added advantage in the all important sprint away from the lights!

roger_merriman

Il Principe wrote:

From the Schwalbe site:

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.

Works for me. My commute is an endless case of accelerate/break repeat ad nauseam. So I'll take that added advantage in the all important sprint away from the lights!

oh god yes, marathon plus tires, at 38mm give even heavy hybrids with hardly light tires even more leaden feeling, mostly away from the lights etc.

nitesight

Just moved from 23's to 25's. A little softer, if anything more surefooted cornering, an improvement for the commute. Have to say that I'm glad I changed. Same sort of speed and performance but just a tad more comfortable. Worth a try.

simon_e

Il Principe wrote:

My commute is an endless case of accelerate/break repeat ad nauseam. So I'll take that added advantage in the all important sprint away from the lights!

Any old excuse, eh

The weight difference between 23 and 28mm for a given tyre is ~40g. Not really significant (but you probably don't care), and TBH 50-100g is unlikely to feel different.

As Sheldon points out (more here, and I've heard said elsewhere too), if in an attempt to reduce deflection your tyres are pumped up too hard they bounce and you are worse off - not only in terms of rider comfort but also traction and speed. A smooth ride is a faster ride. And the UK's roads are not known for their billiard table-like surface (which was where this thread started).

itboffin

DDD bike looked very much like it was rolling with a 28/25 conti set up, looked fine to me.

DDD can you confirm please?

DonDaddyD

28 on the back and 23 on the front. I quite like that set up.

The back is planted the front is twitchy.

What is it with the roads in Wiltshire that you're trying to overcome?

itboffin

DonDaddyD wrote:

28 on the back and 23 on the front. I quite like that set up.

The back is planted the front is twitchy.

What is it with the roads in Wiltshire that you're trying to overcome?

They've never been smooth but the last 12 months has put the nail in the coffin so to speak, imagine riding MTB style single track on your road bike for 40+ miles a day, not only is it wearing through tyres its also harsh so much so lights jump off screws come undone, mud guards fall off and my body is feeling it where I really don't want too.

beverick

Check your rims (if you'll excuse the phrase), you may find that the rim will only take up to a 25c. I tried 28c's on a Rigida DPX rim and it just lifted off the rim as you got towards 5 bar.

Also, tyres of the same size actually differe quite a lot. I have a set of 28c armadillos on the hack and 25c gartors on the roadbike. Looking at them they appear to have the same profile.

Bob

N0bodyOfTheGoat

With my car at the mechanics, I've been forced back onto two wheels for commuting since before the mini Ice Age we had in Southampton during December and January (then I had a chesty infection for almost a month, might still have a little bit of it left)...

Cycled in on the Tricross on Tuesday with 700x25 Stelvio Plus and 32mm Houfflaize tyres. Cycled in today on the Pylon8 on 26"x2.35" Schwalbe Super Motos!

Its great to back on the bikes again, didn't realise how much I missed it until the last few days!

Roastie

I've been testing a bunch of tyres and sizes recently. Bigger tyres (32) don't spin up as easily as narrower tyres (25) - as you'd expect, but in terms of speed once up and running I'd have to say that there is little discernible difference in terms of speed between narrow and wide rubber (of course, talking tyres of comparable quality).

Comfort differences are marked though. For something that I just commuted and perhaps trained on, I don't see the point of running narrow rubber. Plus, the little bit extra you have to put in away from the lights will just make you stronger.

DonDaddyD

itboffin wrote:

DonDaddyD wrote:

28 on the back and 23 on the front. I quite like that set up.

The back is planted the front is twitchy.

What is it with the roads in Wiltshire that you're trying to overcome?

They've never been smooth but the last 12 months has put the nail in the coffin so to speak, imagine riding MTB style single track on your road bike for 40+ miles a day, not only is it wearing through tyres its also harsh so much so lights jump off screws come undone, mud guards fall off and my body is feeling it where I really don't want too.

Carbon fibre seatpost.

In terms of comfort, the single best upgrade I made on my Giant.

It does absorb most of the road vibrations - FACT.