47c vs 35c tyres - differences in speed/comfort or just psychological?

[badgerjockey]

I've been reading up about the move towards wider road tyres to reduce rolling resistance, increase comfort and, potentially, speed. It seems that for racers, there is a sweet spot around the 28/30mm mark beyond which the benefits of the counterintuitively smaller contact patch of a wider tyre begins to be outweighed by the loss of aerodynamics...

There's loads of info about this for this size bracket of tyre, but less so for wider, touring tyres.

I have a hybrid framed tourer and have had 47c 1.75in Conti Contact tyres on it for years. Really comfy and have served me well touring in places like Morocco and Jordan where the tarmac can be poor in out of the way places.

I'm just about to do the Lon Las Cymru, Wales end-to-end and have on a whim bought some 35c Schwalbe Marathon Classics on the off chance that they might roll faster than the 47cs on the good tarmac expected on this route. They are also about 250g lighter each than the Contis.

Am I right, though? According to Bicycle Rolling Resistance the marathons have much less rolling resistance and less weight, but what about internal friction, contact patch sizes, etc etc? The marathons have noticeably stiffer casing and obviously higher pressures...

Sorry, probably just getting myself all confused for not much difference and should've saved the £55!

 

[raleighnut]

I tour on 25s or 28s but don't go 'offroad' much.

 

[ChrisEyles]

Hmm, good question. My impression is that 32mm tyres on my road bikes roll a bit quicker on the road than slick 50mm tyres on my road-ified MTB. But I'd be willing to bet that tyre quality plays just as (if not more) important a role in this as tyre size.

35mm will serve quite well off-road unless you're into proper rocky MTB riding or really gloopy muddy field crossings (where, to be fair, nothing's much fun!).

I'd be equally happy riding on either 35mm or 1.75" on road, but would take the 1.75" for preference off-road.

Not exactly as scientific as your original post, but I suspect you may be overthinking it a tad!

 

[badgerjockey]

Not exactly as scientific as your original post, but I suspect you may be overthinking it a tad!

Me too!!

 

[I like Skol]

Wales is only small, do you really need special tyres to cross it?

 

[Ajax Bay]

Mainly down to tyre quality, not width. The top road tyres are reaching up to 32s now (eg 5000s) but wider than that you need to look for quality tyres and pay for them.
Make comparisons with this: https://www.bicyclerollingresistance.com/tour-reviews
Here's a (deliberately ~10,000m climbing) hilly end-to-end (Cardiff > Caernarfon) and back I've (audax) planned: https://ridewithgps.com/routes/32851041?beta=false
But all tarmac, just about.

the benefits of the counterintuitively smaller contact patch of a wider tyre

For accuracy's sake, the contact patch of a wider tyre is NOT smaller: at the same pressure it's shorter (and wider obv) so a different shape. But at the likely reduced pressure in a wider tyre the contact patch will be larger (fisiks init).

 

[CXRAndy]

Regarding rolling resistance, tubeless is the way to go. Size of tyre, well that depends on majority terrain.

You're right about 28/30mm max optimal for road, however I run 38/40mm Schwalbe G Ones tubeless setup.

I have averaged over 20 mph for 20 miles, and 19 mph over 70 miles on club runs, so the tyre is no hindrance.

The comfort is fantastic too

 

[Drago]

Once you her beyond a certain point the additional rolling mass begins to outweigh any benefit from reduced rolling resistance. Where exactly that point will be depends on so many factors that the only way you'll know is to try some tyres and see for yourself.