Tyre width vs efficiency?

[Pedalo]

Hi, I was wondering how much tyre width affects efficiency (and therefore range) of an electric bike. For example if I had a bike fitted with 700 c32 tyres how much more range might I get for switching to 700 c28. Or how much worse would it be with c38?

Has anyone looked at optimising their range by switching to thinner tyres?

 

[flecc]

It makes very little difference at any given pressure, a point that tyre maker Schwalbe often make being that the longer contact patch of the narrower tyre brings it equal to the wider one on the larger section tyre. There's only a gain if the narrower tyre is run at much higher pressures with the discomfort that brings. The gain even then is extremely small and might be difficult to measure, so it's debatable whether it's worth giving up the comfort.

I did try it on one e-bike and couldn't tell the performance difference, and that was with a greater difference in sizes.
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[jerrysimon]

On the roads and paths I ride on I would be shaken to bits on wheels that thin

Regards

Jerry

 

[Barnowl]

Good question Pedalo and one I've asked myself. Fleccs answer sounds spot on as usual.

I considered dropping from 32s to 28s but decided it probably wasn't worth it. Chris Bike (another forum member of Cytronex fame) last year changed his tyres from Bontrager 32s to Conti (4 seasons?) 28s and as I recall found them livelier.

http://www.pedelecs.co.uk/forum/electric-bicycles/2176-trek-cytronex-first-impressions-12.html?highlight=conti#post28819post28815

http://www.pedelecs.co.uk/forum/electric-bicycles/2349-pro-connect-first-range-test-9.html?highlight=conti#post34111post34111

I'm sticking with the 32s for 3 reasons - I don't have to buy and fit a new pair of tyres, I value what little comfort I have and I'm a bit iffy about the extra vibration/jolts on the front hub motor especially with the aluminium forks.
If you do decide to change though I'd be interested to know how you get on.

 

[monster]

tyre width/size/tread all make very little difference. like +2%. if you want more range the only way is to buy a second battery or go slower (less wind resistance).

 

[bode]

I use Schwalbe Marathon Plus 20x1.75, whose recommended inflation pressure is up to 70 psi. I inflate to 65 psi, which obviously makes for a firmish, not to say somewhat jolting ride.
What would be a sensible lower pressure to give a bit more cushioning without making them too vunerable to punctures?

 

[flecc]

That's the same as my Q bike tyres. The recommended pressure range is 45 to 75 lbs per sq.in. and I happily run my lightly loaded front tyre from 55 declining to 45 lbs or even below before re-pumping to 55. The more heavily loaded rear I run at 60 declining to about 50. I've never had a puncture in 2 years 5 months on these tyres on this bike.
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