James Thinks

writing is a kind of thinking

Following on from my previous real-world tyre experiments, I finally got around to a more thorough test.

As before I tested Schwalbe Marathon Greenguard 25mm tyres against Michelin Pro4 Endurance 28mm tyres. One of the Michelins had been used for a couple of hundred kms, but the other three were new.

The Schwalbe Greenguards are one of the faster popular commuting/touring tyres and very good value. They have a wire bead and significant tread depth, so are the heavier and tougher of the two. The Michelins are very popular among audaxers as being a bit faster than the old favourite of Continental 4Seasons while still having good protection and grip.

Once again I used 3km climb up "Road hill climb" through Ditteridge. I considered only the uphill part of the ride as the descents are very variable due to unexpected traffic and how much braking I decided to do. I didn't brake at all on the climbs.

The main difference this time was that I repeated the climb five times which each pair of tyres at the same pressure. I chose 55PSI front and 65PSI rear as this seemed to be the best pressure from the previous test.

Route: 3.2km climb up "Road hill climb" through Ditteridge. I didn't measure the descent as it depends more on wind resistance.

Power: 200W average. A power I can consistently and repeatedly produce for the time it takes to climb this hill.

Wheels: Both tyres changed.

Measurement: The total lap time for climbing the hill. With consistent power this should show any differences in the drag of the set up.

Possible confounding factors

See previous test

Results

Tyre Lap power Lap time
Schwalbe Marathon Greenguard 25mm 198 00:12:35
Schwalbe Marathon Greenguard 25mm 199 00:12:33
Schwalbe Marathon Greenguard 25mm 199 00:12:29
Schwalbe Marathon Greenguard 25mm 200 00:12:40
Schwalbe Marathon Greenguard 25mm 199 00:12:25
Michelin Pro4 Endurance 28mm 199 00:12:24
Michelin Pro4 Endurance 28mm 199 00:12:04
Michelin Pro4 Endurance 28mm 199 00:12:13
Michelin Pro4 Endurance 28mm 198 00:12:16
Michelin Pro4 Endurance 28mm 199 00:12:15
Results Time
Av. Marathon Greenguard 00:12:32
Av. Pro4 Endurance 00:12:14
Difference 00:00:18
Time difference over 100km (uphill) 00:10:00

An 18 second difference over 3km uphill is equivalent to a 10 minute difference over 100km uphill. I'm going to assume that most 200km rides are circular and therefore 50% uphill and that the speed difference downhill is negligible. So I think we can perhaps say an extra ten minutes on a 200km ride with the Schwalbe Marathon Greenguards. That's well within the nautral variation or noise when I ride a 200km. If I did the same route on different days it could easily vary by 30 minutes, so it would be hard to tell. Also, the estimate might be slightly off as I would normally produce less than 200W all the way around a 200km.

Conclusions

I'm happy that the results are clear cut which seems to further validate the testing method. There's clearly a fair bit of noise, with up to 15 seconds difference between runs with the same tyres, but all the Michelin results were all ahead of the Schwalbe ones.

The Michelin Pro4 Endurance is at the durable end of "fast" road bike tyres, and Bicycle Rolling Resistance reports a drag of 14.2W in laboratory conditions.

The Schwalbe Marathon Greenguards are at the faster end of touring tyres. They are tough. I've only had one puncture in the 13500km the last set lasted and that was in Chiltern flints when a shard the size of one of my teeth embedded itself. They are not quite as puncture resistant as the Marathon Plus (25.5W), but they roll much better, BRR says they use up 21.3W of power each.

21W vs 14W is about an extra 50% more power for the Schwalbes, so I had expected the time difference to be larger, especially considering that the Schwalbes are heavier which would slow me down on a climb. However, even 43W (2x21.3) is only a little over 20% of the 200W I was putting out, so most of the power is going elsewhere - potential energy when climbing and wind resistance.

So if we're only considering overall speed on a long ride it's not an easy decision which tyres to use. In my experience, on the roads I ride, the Michelin Pro4 Endurance puncture about once every 1000km. That usually takes me 20 minutes to fix if it's dry and daylight, but can be much longer sometimes and forces me to carry several spare tubes. So on a 200km ride in good conditions I'd expect to be faster with the Michelins, unless I get a puncture in which case I'll definitely be slower, but that would only happen 1 in 5 rides.

Using the Schwalbes, punctures happen "almost never", so even on a long ride I'd only carry one spare tube, reducing the weight penalty a bit. I like being confident in the tyres when descending or travelling over bad surfaces. Punctures are a nasty surprise at the best of times, but when it's 11pm and I'm up a Welsh mountain in the rain, it is at best demoralising and at worst leaves me dangerously exposed in the elements. So I'm happy to trade a bit of speed for a lot of reliability. When I take into account the fact that Schwalbe Marathon Greenguards are relatively inexpensive and last at least twice as long as faster tyres, they make a lot of sense to me.

Mugshot of James cycling on a road in the sunshine.

James Bradbury

I write about whatever is on my mind. I do so mostly to help me think more clearly. If other people find it interesting that's good too. :-)

Read more...

I repeated the climb five times with each pair of tyres at the same pressure

I've only had one puncture in 13500km

I'm happy to trade a bit of speed for a lot of reliability