Schwalbe Marathon/Marathon Plus de facto PSI

[Crankarm]

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[CopperBrompton]

Willem's post is contradicted by every article ever posted by a tyre manufacturer ...

Lower pressures = greater puncture risk. Within the manufacturer recommended range, lower pressures will be more comfortable, higher pressures will have reduced rolling resistance. The optimum pressure will vary by rider, both in terms of weight and personal susceptibility to vibration. For me, the optimum is a wide tyre inflated to the maximum recommended pressure.

 

[snailracer]

Willem's post is contradicted by every article ever posted by a tyre manufacturer ...

Lower pressures = greater puncture risk. Within the manufacturer recommended range, lower pressures will be more comfortable, higher pressures will have reduced rolling resistance. The optimum pressure will vary by rider, both in terms of weight and personal susceptibility to vibration. For me, the optimum is a wide tyre inflated to the maximum recommended pressure.

I take it that you do not believe in suspension losses?

 

[CopperBrompton]

I take it that you do not believe in suspension losses?

You do? Why so?

 

[sabian92]

I run 25x700c Marathon+ at 115psi, just to throw that out there. I'm a heavy guy though, 15 and a half stone.

 

[snailracer]

You do? Why so?

Have you ever noticed that you slow down when riding over heavily-textured tarmac roads? That's mostly due to suspension losses.

Suspension losses describe the energy wasted in the rider's body (& luggage) as it jiggles in response to vibration transmitted to it due to the roughness of the road. Energy is lost as heat, by the same viscous, frictional and elastic mechanisms that take place in car shock absorbers.

I don't think it's tenable to deny that suspension loss exists, the only question is whether they are significant enough to be noticeable in comparison to other bike/tyre losses. These folks persuaded me that they are:
http://janheine.wordpress.com/2010/10/18/science-and-bicycles-1-tires-and-pressure/

Suspension losses are not the same thing as losses due to classic "rolling resistance", which are due to frictional and deformation losses that happen within the tyre itself. Sometimes both suspension losses and classic rolling resistance are lumped together as "rolling resistance", but that is just layman's imprecise use of the terminology.

Tyre manufacturers measure classic "rolling resistance" by running tyres on a smooth steel drum, which unquestionably reduces as tyre pressure is increased. However, real roads are not as smooth as the steel drum, and suspension losses increase as tyre pressure increases (i.e. the rider jiggles more), even as losses due to classic rolling resistance reduce.

Tyre manufacturers fully understand suspension losses. I can only suggest the following reasons why they don't talk about it:

1. It's too complicated to explain and they risk annoying customers who don't understand their explanation
2. Trade secrets
3. It shows that there is a point beyond which the tyre itself doesn't matter much - which doesn't help sell expensive, high-end tyres
4. They can't (or won't) agree a standard with other tyre manufacturers over how rough a "real" road or how lossy a rider's jiggling body should be.

Tyres used in velodromes (i.e. smooth surface) are often inflated to over 200psi. However, nobody uses such high pressures on the road, even for short time-trial racing, because they'd be slower, even if they don't fully understand why.

The concept of suspension loss is well-established in highway engineering circles, as it has direct impact on the fuel consumption of vehicles using roads.

 

[CopperBrompton]

You misunderstand. You said:

I take it that you do not believe in suspension losses?​

and I asked why you would make that odd assumption?

 

[snailracer]

You misunderstand. You said:

I take it that you do not believe in suspension losses?​

and I asked why you would make that odd assumption?

Reading your post again, I think I did misunderstand, apologies.

Lower pressures = greater puncture risk. Within the manufacturer recommended range, lower pressures will be more comfortable, higher pressures will have reduced rolling resistance. The optimum pressure will vary by rider, both in terms of weight and personal susceptibility to vibration. For me, the optimum is a wide tyre inflated to the maximum recommended pressure.

Your post suggests that running at a pressure less than the maximum simply results in more resistance - that is what I disagree with, as it does not account for reduced suspension loss, which affects the overall resistance.

 

[CopperBrompton]

Mostly I was taking issue with the puncture risk, but on typical road surfaces somewhere close to the maximum pressure will be fastest. I agree things will be different on a very rough surface.

 

[MacB]

I've read lots of the studies, articles and opinion pieces and would immediately argue that Willem does not contradict everyone out there, far from it actually especially in terms of touring.

But I've given up arguing the toss about this sort of stuff, all I can say is that my own experience has led me to adopt the sort of approach Willem advocates. Loads of factors go into this personal decision but wider and softer is the way I like to roll, personally and on a bike

What I can say for a fact is that the fear of pinch punctures etc is vastly overstated, to the point at which I wonder what it is based on. For most of my miles I've been over 15 stone and a lot have been done between 17 and 19 stone, both with and without luggage. I've never gone above 100psi even with a 23mm tyre and had no problems with punctures.

Quite how someone weighing in about the same as my left leg can claim they need over 100psi to avoid pinch punctures. Either it's nonsense or they have no road sense and ability to avoid crazy potholes.

 

[CopperBrompton]

Pinch punctures should be rare with any sensible pressure, but conventional punctures are more likely at lower pressures.

 

[Crankarm]

I've read lots of the studies, articles and opinion pieces and would immediately argue that Willem does not contradict everyone out there, far from it actually especially in terms of touring.

But I've given up arguing the toss about this sort of stuff, all I can say is that my own experience has led me to adopt the sort of approach Willem advocates. Loads of factors go into this personal decision but wider and softer is the way I like to roll, personally and on a bike

What I can say for a fact is that the fear of pinch punctures etc is vastly overstated, to the point at which I wonder what it is based on. For most of my miles I've been over 15 stone and a lot have been done between 17 and 19 stone, both with and without luggage. I've never gone above 100psi even with a 23mm tyre and had no problems with punctures.

Quite how someone weighing in about the same as my left leg can claim they need over 100psi to avoid pinch punctures. Either it's nonsense or they have no road sense and ability to avoid crazy potholes.

It's not tyres or even tyre pressures that is the problem for these cyclists, but eye sight. Should have gone to SpecSavers comes to mind.

 

[ChrisBailey]

I'm about to shift allgiance (I think) from Continental to Schwalbe, and I'm curious about ACTUAL psi for the Marathon or the Marathon Plus, 26 x 1.75. The rating is 45-70psi. Is anyone running these tires above that?

My old Continental Travel Contacts (26 x 1.75) are rated at max 80psi, but I consistently run them at 90 without a problem.

Is anyone inflating the Marathon (or Plus) to 80 or 85?

My commute is either 12 or 15 miles depending upon route, the 15 miles route was almost always faster as it contains much more continual cycling, less give ways, roundabouts, traffic lights etc. Then I switched from my Marathon plus's (Crazyguy has its own equivalent of helmet/mudguard flame wars on these tires) to Marathon Racers, not lightweight but ~50% of the weight of the Plus's and the time on the different commutes is almost identical. The effort to get those brutes (the plus's) turning is a significant factor. I run all my tires at the top end of the manufacturer's guidance FWIW.

I think I understand the argument related to rolling resistance and tire width, but tire weight is very noticeable. I will not commute on plus's again as the puncture rate for me has always been minimal, maybe 1 a year, seemingly irrespective of brand, and as to touring (this forum) I never have and never will.

Not sure how off topic this response is, but if the question of the OP is ultimately what is most efficient tire to ride given the associated width/pressure/weight/puncture concerns then my vote for touring is to veer from the tire pressure to tire weight, think Durano, Duraskin or Armadillo, for cummuting if the puncture issue is more significant, marathons or marathon racers, but I would only go plus's if the ride is extreme, along glass strewn paths or similar.

Chris

 

[CopperBrompton]

Marathon Plus versus a lighter tyre for me comes down to two questions:
1. How much hassle is a puncture for you?
2. How much of your cycling is start-stop versus cruising?

The first is obvious. Personally, I'm a mechanical illiterate and changing a tube on the rear tyre would take me about a fortnight and result in the deaths of several innocent bystanders. If you can change a wheel in less than ten seconds by the power of thought, your priorities will be different.

The second is less obvious. A heavier tyre takes more effort to accelerate, but once at cruising speed, it actually helps maintain your momentum better than a lighter tyre (think about how a flywheel works). So for lots of stop-start riding, a heavy tyre penalises you, while on a cruising ride, a heavier tyre assists you.