Author Topic: Rolling Resistance of "Balloon" Tyres/Tires  (Read 514 times)

energyman

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Rolling Resistance of "Balloon" Tyres/Tires
« on: March 21, 2019, 03:59:40 PM »
Does any body know if the rolling resistance of 2.15 Balloon tyres is more than say Marathon Plus 1.5 tyres ?
I have an E-Bike with balloons (Big Bens) which does not have the same range as my wife's E-Bike with 1.5 Marathon Plus .
Same battery, same motor.
Yes - she does weigh less than me !

julk

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Re: Rolling Resistance of "Balloon" Tyres/Tires
« Reply #1 on: March 21, 2019, 07:44:57 PM »
I find wider tyres run at lowish pressure have the lowest resistance.
Plus they absorb road shock better.

I am sure Andre will be along soon to give the low down on this…
Julian.

energyman

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Re: Rolling Resistance of "Balloon" Tyres/Tires
« Reply #2 on: March 22, 2019, 10:03:50 AM »
Thanks - that's what I'm hoping !

Mike Ayling

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Re: Rolling Resistance of "Balloon" Tyres/Tires
« Reply #3 on: March 23, 2019, 03:38:42 AM »
Does any body know if the rolling resistance of 2.15 Balloon tyres is more than say Marathon Plus 1.5 tyres ?
I have an E-Bike with balloons (Big Bens) which does not have the same range as my wife's E-Bike with 1.5 Marathon Plus .
Same battery, same motor.
Yes - she does weigh less than me !

Yes - she does weigh less than me !
And she might pedal more/harder than you do!

Mike

Andre Jute

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Re: Rolling Resistance of "Balloon" Tyres/Tires
« Reply #4 on: March 23, 2019, 05:08:05 AM »
Does any body know if the rolling resistance of 2.15 Balloon tyres is more than say Marathon Plus 1.5 tyres ?
I have an E-Bike with balloons (Big Bens) which does not have the same range as my wife's E-Bike with 1.5 Marathon Plus .
Same battery, same motor.
Yes - she does weigh less than me !
I find wider tyres run at lowish pressure have the lowest resistance.
Plus they absorb road shock better.

I am sure Andre will be along soon to give the low down on this…
Julian.

I'm afraid the low down on this one is GO ON A DIET! No, really, when you're putting out a fifth of a horsepower or, usually, much less, mass is the greatest determinant of everything to do with a bicycle. In the end, much as touring cyclists may struggle against the pernicious racing legacy infecting everything, we are perforce all weight weenies.

Besides the human factors that everyone has already referred to -- that your wife is lighter, that she may be pedalling more, that she may be using the gearbox more efficiently, or the modes of the motor ditto -- there are also also often said to be technical factors to do with the relative condition of the two batteries, though I must tell you that my experience is that modern electric bike batteries, if you pay for the best and take care of them (keeping them in the main fully charged after even the shortest ride), do not decline into old age either steeply or soon. Jan Heine has built a line of boutique tyres on another factor which aids comfort and secure roadholding on the bike, and may also contribute to low rolling resistance: compliance to the road, particularised by Heine as soft sidewalls. The Big Apples have some of the softest sidewalls I have ever felt on a bike tyre.

The difference in the power required if the tyres on your two bikes are inflated to the same pressure is likely to be at least 10W or around 7% of your nominal output -- in favour of the bike on balloons. You should, if we could isolate the other factors, be able to leave her behind. Here's a graph, courtesy of Schwalbe at https://www.schwalbe.com/en/balloonbikes.html --



-- which shows what the tests the Deutschen Sporthochschule, Köln conducted on balloons and other tyres at their specially built multi-surface track discovered. In short, the 37mm tyre needs to be inflated to a jarring 4 bar to enjoy the same low rolling resistance as the rider of the 60mm tyre enjoys at a cushy 2 bar. As I'm sure you know, comfort over a day's ride translates into greater reserves at the end of the day.



PH

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Re: Rolling Resistance of "Balloon" Tyres/Tires
« Reply #5 on: March 23, 2019, 01:41:49 PM »
The difference between the power required to move two cyclists of different sizes and shape on the flat will almost entirely be due to aerodynamics.  Other factors do of course play a part, but pale by comparison if riders are of considerably different shapes.  From memory - at 15 mph on the flat 85% of your power goes into displacing the air!  Time trial riders are happy to add weight for aerodynamics, while hill climbers will do the opposite.  For leisure cyclists the difference is often masked by the power output available, as a simplistic rule the larger the bulk of the rider the higher that is.  If you introduce power assist then it becomes obvious that to maintain the same speed that assistance for a less aerodynamic rider will also need to increase. You can fiddle with the other elements, weight, rolling resistance, mechanical efficiency... they will all make some difference and on an incline a considerable one, but in the course of a normal days ride very little. 
For two e-bike riders, the most efficient thing to do would be to draft, the difference is likely to be enough for the following rider to not need the assistance.  Take turns and you could get close to doubling the range, if that's what you want.
The weight Vs aerodynamics argument is as old as cycling, it's a shame most of the research is sports based, it effects all of us every time we get on a bike. Here's a fun calculator,  for myself, 90kg and maintaining 20 kph in a moderate wind and including little climbing - adding 10kg requires an extra 4 watts, moving from the drops to the bar tops requires an extra 16.

http://bikecalculator.com/what.html

martinf

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Re: Rolling Resistance of "Balloon" Tyres/Tires
« Reply #6 on: March 23, 2019, 07:53:05 PM »
Agree that aerodynamics is the most important variable on the flat at moderately fast speeds.

I can easily feel the difference in comfort and rolling resistance between tyre extremes (for example Marathon Plus, which are uncomfortable and slow in 700C x 28 and Schwalbe One, which are both more comfortable and faster in the same size and pressure).

Go slower, and tyres become more noticeable. Over hilly routes, the uphill bits are perforce slow, so an efficient tyre helps, though this is perhaps as much from better morale as from the real differences in efficiency.

I even go to the trouble of fitting latex tubes on some of my bikes. I reckon the small gain in comfort and efficiency over butyl is worth the extra hassle from inflating the tyre more often and replacing the tubes more often (they perish quicker than butyl).

energyman

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Re: Rolling Resistance of "Balloon" Tyres/Tires
« Reply #7 on: March 27, 2019, 09:01:41 PM »
Thanks everyone.
The BigBens are staying.
I'm now on a diet & shaving my legs and possibly removing my beard and maybe one of those odd shaped helmets to improve my streamlining.