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Changed back tyre 700x35c (WTB ALLTERRAINasaurus) to 700x23c (Schwalbe Lugano) and front rim from 18 to 13 inner width (photo below), is it better to change rim or tyre size to get lower rolling resistance ?

One of changes made significant improvement (>20% shorter travel time), but not sure which one.

Photo from test

Pressure around max 500kPa front, 700kPa back (max. >8bars)

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    I gave an answer, but also voted to close as too broad. Stack Exchange sites look for distinct questions with factual answers, they do not lend themselves well to discussion type questions – Andy P Aug 5 '19 at 7:48
  • In case someone do not want to ignore physics, every time there is some deformation of tyre, rolling loss depends most on its material and thickness where it is deformed, so you may have hard&fat everlasting and puncture proof gum or light thin construction which does not stand too long and is easier to puncture. Another option is fatter slider and move most of deformation to thin side, but then also rim width play some role. Try to touch and measure different tyres, compare thickness with rolling test results if you do not trust still. – Tom Aug 6 '19 at 20:20
  • Today bought foldable, boxed Conti Race King as a gift and there was table of compatible rims. For 35 tyre 18 or 20 wheelbase or 17C or 19C for hooked rims. For 23 tyre 16 vs 13C or 15C. So good producer has manual and specification for rims too. (Tyre was MTB 26x2.2 or 55-559, absolute winner in a test) – Tom Aug 31 '19 at 18:19
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The tire change would have been the biggest change, the ALLTERRAINasaurus is a knobby tire, while the Lugano is a slick road tire.

Years back I used an ALLTERRAINasaurus and it had to be one of the slowest touring tires I have used in my life. Some earlier versions I later found out also had an incredibly stiff casing making it even less efficient.

I have also ridden on Lugano as well. It is a slower tire too, kind of like a gatorskin, but no where near as slow as the ALLTERRAINasaurus.

Note that your pressure could be an additional confounded factor, that said from my experience with both tires I would put money on the the tire change being the culprit. The rear wheel also carries the most weight so will be disproportionately affected by rolling resistance.

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All the recent research shows that wide tyres outperform narrow ones in terms of rolling resistance. However the biggest determinant of tyre performance is the quality of the casing. A high quality supple casing allows the tyre to deform round small imperfections in the road surface more easily and lose less energy.

Unfortunately most (there are some exceptions) touring tyres are not made with high quality casings, so have a harsh ride and poor rolling resistance.

Schwalbe have a page dedicated to explaining rolling resistance: https://www.schwalbe.com/en/rollwiderstand.html

If you are interested in performance of certain tyres you can find some independent testing on the following site: https://www.bicyclerollingresistance.com/

In terms of rims, the trend is also to go wider - the wider rim has the effect of making the contact patch of the tyre wider (hence reducing rolling resistance) and also reducing the 'lightbulb' effect of high volume tyres improving the aerodynamic performance.

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    If you are unwilling to accept any of the existing data, your only option is to get yourself a power meter and go to your local closed road circuit and ride laps at a known power with different combinations – Andy P Aug 5 '19 at 8:25
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    If you actually read bicyclerollingresistance.com, you'll find out that wider tires have advantage only if you have them at same pressure than narrow ones. If you use suitable pressure for each size, the rolling resistance is almost equal. – ojs Aug 5 '19 at 8:34
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    @Tom On one hand you continually ask for scientific data, and yet on the other hand, the only testing you are willing to do is unscientific 'seems faster' with 'random wind'. Riding multiple laps of a circuit at a known power gives is the best test the average person can perform as they don't have access to a wind tunnel – Andy P Aug 5 '19 at 8:35
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    >20% speed increase on daily 20km track is good for comparision and do not have electric bike to compare power used. There is special asphalt way made for bicycles only (granted by EU), so no worry about surface. – Tom Aug 5 '19 at 8:38
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    @AndyP Care needs to be taken when interpreting the rolling resistance (RR) data. When tire construction is the same and pressure is adjusted to give similar comfort, tire width doesn't noticeably impact RR. Thinner tires often fall short in the real world, as you can't let out enough pressure without risking rim strikes. This means on real roads you are more likely to encounter the RR break point with thinner/lower volume tires. – Rider_X Aug 7 '19 at 21:33

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