A tale of two tyres (or four or six)

Ignorance was bliss: I thought I was happy with Brown Bike's Schwalbe Marathon 28mm tyres.

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I have heard that, when everything else is equal:

(a) Wide tyres have less rolling resistance than narrow ones.
(b) Tyres at high pressure have less rolling resistance than at low pressure.
(c) Tyres at high pressure are less comfortable than at low pressure.
(d) Pressures make some difference to puncture probability but, snakebites aside, people disagree about which way it goes.

Brown Bike has always worn the widest he can, 28mm, so (a) was irrelevant to me. My old track pump wheezes at 85 psi, so that's what I've been giving the rear tyre with a little less in the front. I'm not a speed-freak and I've never Joggled, although I'm aware that fellow-blogger Mick is happy touring on anorexic tyres. But he's a fitter, hardier cyclist than me, so that wasn't relevant either.

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So far so good. I was happy and Brown Bike was happy. True, his sister Ruby is sleek, sexy and fast, but she's lighter and not encumbered with heavy D-lock, rack and mudguards. She's a racer, not a tourer. She runs on 23mm tyres, and I was pleased to find they were not grossly uncomfortable. She tends to slip on hoggin surfaces, but I avoid those.

Then I bought a secondhand pair of wheels to go on either bike. They are "just in case", an insurance policy. I had to test them out, so swapped them on to BB. They worked fine for a lap of the village green, so we went shopping. No problem, and to my surprise BB felt exactly as before. Schwalbe Marathons (28mm) and Specialised All Condition Armadillos (23mm), at the same pressures, on roads, seem to have equal comfort levels.

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Lidl sold me a track pump for the princely sum of £4.99 that turned out to be better than my old one, and easily capable of squeezing 125 psi into the 23mm Armadillos. So we trotted off again. But it must be spring, because BB took off like a bicycle re-born. He sprinted off with ants in his pants; I couldn't hold him back. I exagerate slightly, but there was no doubt that shoving an extra 50% of pressure in his tyres greatly reduced the rolling resistance.

Of course, the gravel on my drive pinged away like bullets as we rode out. And, of course, the nail-hard tyres were agony to ride on, weren't they? Actually no. They might have transmitted slightly more vibration but nothing worth complaining about. Besides, Lidl has also supplied comfortable padding for my posterior.

My informal trials have confirmed points (a), (b) and (c) above. I'll try to do something a bit more scientific, like Mick's Gunnislake Station roll-out tests, but my current thoughts are:

(a) If 28mm Marathons have less rolling resistance than 23mm Armadillos (at the same pressure), I don't notice the effect.
(b) Armadillos at high pressure have far less rolling resistance than at low pressure.
(c) Armadillos at high pressure aren't much less comfortable than at low pressure.
(d) No evidence yet about punctures.

Point (c) is subjective, and anyhow my comfort level falls when I'm knackered, so a tyre that gets me there with less effort could be more comfortable overall. Point (d) couldn't be established in less than a zillion miles.

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These particular Armadillos are too worn to consider taking to Yorkshire, so I'd have to get new ones. Or narrower and higher-pressure Marathons. Or something else that likes high pressure. True, BB looks somewhat ill-shod in anorexic tyres, and they might not suit muddy Yorkshire moors. I have discovered that the Lidl track pump fits neatly under his top tube, if I can figure out where to put the D-lock. Or maybe we'll leave that at home.

Is Brown Bike turning into a boy racer? Perhaps, but he needs a stronger motor. I did 36 miles today at a paltry 10 mph.

6 comments on “A tale of two tyres (or four or six)”

  1. Patrick wrote:

    The mileage is creeping up nicely Alan. :-)

    I've never used less than 32mm. My tourer was supplied with 37mm tyres and my road hybrid 40mm, although I've recently put 32mm on both. My other bikes have been MTBs.

    I don't believe wide tyres have less rolling resistance than narrow ones. Both my road bikes feel livelier with their thinner tyres, no question. It might be partly due to them being lighter than the 37s but I'll bet there is also less rolling resistance from reduced contact with the road – that is with 80psi on the front and 90 on the back. One of the sets of 32mm is folders and they are quite a bit lighter. They feel significantly quicker than the ones I got used to throughout 2009 and 2010 – the original touring tyres.

    All these tyres are comfortable to ride on, but they are all biggish tyres. I wouldn't fancy a full day's cycling on 23mm tyres but I'm saying that never having used any. I do know I don't like being bumped about.

    My thoughts:

    (a) Wide tyres have more rolling resistance than narrow ones.
    (b) Tyres at high pressure have less rolling resistance – proved by Mick.
    (c) Narrow tyres are mechanically faster but more tiring over several hours.
    (d) Less tyre contact with the road (higher pressure) = fewer punctures.

  2. Hilary wrote:

    I have Schwalbe Marathons in 26×1.5 on Why? bike but I can't say I find them terribly comfortable and am thinking of changing to something with more flexible sidewalls like Panaracer Pasela but they are more prone to sidewall punctures.

    Roberta sports 28mm Conti Gatorskins in winter and 25mm Michelin Krylion in summer. Both are very puncture resistant but the Krylions with their go faster stripes are lighter and feel faster altho I suspect this could be purely subjective! Both are equally comfortable to ride.

  3. Kern wrote:

    We started riding with 35mm on our hybrids. By now I'm down to 28mm and it makes a big difference (less resistance). I had not thought about Patrick's (d) before, but it makes sense that less surface contact reduces the odds of a puncture.

    Three-and-a-half hours in the saddle is a good day's riding – well done.

  4. Alan wrote:

    I forgot to mention that the purpose of yesterday's trip was to return the crutches. Shame, really, as overtakers gave me more room when they were strapped to the rack.

  5. Patrick wrote:

    Here is Schwalbe's explanation of why wider tyres have less rolling resistance.

    I don't think they mean 40mm is faster than 23mm, even with the same pressure. They are perhaps ignoring weight and friction. A wider tyre just stays rounder.

  6. Garry wrote:

    I mostly cycle on 26 inch wheels and my favourite tyres by far are Specialized Fatboys. These are nominally 25 x 1.5" and are slicks. You can pump them up to 100psi and I usually do. They are fast. I've used these tyres for maybe 15 years.
    On my racer, which I don't ride much, I use whatever they came with. 23C I think at 120psi.
    My 700c tourer died of a myocardial infarction more than a year ago. I used to tour on 32C tyres, at least on the back. I have toured on 37C as well.

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