Tire question

[GTR2EBIKE]

So I have 2 sets of tires that I have had on my e-bike and I wanted to find out which one would be more efficient to run here are the specs
Tire Size Circumference@60psi Revolutions per mile
MTN 26x2.1 81.5 in. or 2068 mm 777.5
Road 26x2.0 79.5 in. or 2018 mm 797.0
Which would get me where I want to go faster and with less energy consumed?
I know the road tire will have less rolling resistance but how much of that extra energy that i'll be saving will have to go to spin the wheel and tire 20 more times in a mile.
Just to let you guys know I have a BMC 1000w motor if that makes a difference. I'm pretty new to e-bike and electric motors in general, obviously turning the tire 20 more times in a mile will increase the rpm of the motor but does more power draw come with more rpm or no because the bike will have less resistance? Thanks for the help and please let me know if you need anything cleared up or any more measurements.

 

[dogman dan]

I think you know the answer, efficiency is all going to depend on lower rolling resistance, lower air resistance etc. Even with motors, I can feel it that a good road tire or hibrid tire is better than big off road knobs. But if you battery is sized correctly, that is big enough, it really does become a question of how many angels can dance on a pin. If your battery and motor setup has decent reserve, say 3-4 miles further than your typical trip, what's the difference if you use a tire that cuts range by 1/2 mile?

As I say all this, I do admit that I never did any real world tests of this effect of tires on range myself. Pedaling of course, you feel a huge difference, but motorized, I doubt it matters as much as having the kind of tire you like, for the riding you do. So don't hesitate to choose the dirt tire if you ride dirt, or the street tire for street, or in between tires for have it both ways.

 

[GTR2EBIKE]

I think you know the answer, efficiency is all going to depend on lower rolling resistance, lower air resistance etc. Even with motors, I can feel it that a good road tire or hibrid tire is better than big off road knobs. But if you battery is sized correctly, that is big enough, it really does become a question of how many angels can dance on a pin. If your battery and motor setup has decent reserve, say 3-4 miles further than your typical trip, what's the difference if you use a tire that cuts range by 1/2 mile?

As I say all this, I do admit that I never did any real world tests of this effect of tires on range myself. Pedaling of course, you feel a huge difference, but motorized, I doubt it matters as much as having the kind of tire you like, for the riding you do. So don't hesitate to choose the dirt tire if you ride dirt, or the street tire for street, or in between tires for have it both ways.

I was asking if the mtn tire is worth using, it will definitely provide a higher cruising speed at the same motor rpm because it has a larger circumference but I want to know if the drag that it has on top of the road tire makes it worth using the road tire which has a smaller circumference but could be worth using because it has less drag. Is that a better way to phrase it

 

[Drunkskunk]

Tire Size Circumference@60psi Revolutions per mile
MTN 26x2.1 81.5 in. or 2068 mm 777.5
Road 26x2.0 79.5 in. or 2018 mm 797.0

You have a 50mm diffrence on 2000mm diameter tires. thats 00.25% diffrence.

Depending on at what point in the efficancy curve you are, that might mean the larger tire goes farther by 00.25%, or it might mean it takes 00.25% more energy to move the bike the same distance.

But you'll affect your range more by deciding on wether to take a dump or not before your ride. that extra 00.5% weight penelty will be more detrimental.

 

[GTR2EBIKE]

Tire Size Circumference@60psi Revolutions per mile
MTN 26x2.1 81.5 in. or 2068 mm 777.5
Road 26x2.0 79.5 in. or 2018 mm 797.0

You have a 50mm diffrence on 2000mm diameter tires. thats 00.25% diffrence.

Depending on at what point in the efficancy curve you are, that might mean the larger tire goes farther by 00.25%, or it might mean it takes 00.25% more energy to move the bike the same distance.

But you'll affect your range more by deciding on wether to take a dump or not before your ride. that extra 00.5% weight penelty will be more detrimental.

How is that a 00.25% difference. 2000/50=40 100/40=2.5 it ends up being roughly 2.47%. If you need me to break it down more look at the inches they are 2 inches apart at roughly 80 inches when you would get to 100 inches they'd be roughly 2.5 inches apart. On a 10 mile ride that's a quarter of a mile gained or lost.
Your correct on the second part which is why I'm asking if anyone has an direct knowledge of this.
And no weight and revolutions of a tire have no direct correspondence to each other

I guess i'll just test it myself limiting the amps and go wide open down the same stretch of road and see what the numbers end up being. If anyone has some real info to contribute please don't hesitate to post it.

 

[Papa]

I would strongly discourage off-road tires on asphalt. The rolling resistance (RR) is higher, inferior traction, noisier, and wear-out much sooner.

http://www.schwalbetires.com/tech_info

 

[DAND214]

I'm with PaPa on the rolling resistance. Running mtn tires on my Blackcomb or using road tires my choice is the smooth tire. If you are on the power all the time you might not see a big differance but as you learn to pedal and use less power the smooth tires will be the winner. Knobbies have a lot of drag and just rolling down a hill side by side the road tire is faster and rolls longer.
Hands down it's the road tire.
Dan

 

[dogman dan]

I wrote that poorly again. But the point was that the feeling like your tires are in molasses when street riding a dirt tire is going to affect your range the most. But so what if it does, as long as the tire you choose fits the kind of riding you'll do, street, dirt, or mixed.

The real solution of course, is a fleet of ebikes, one for street, one for dirt, etc.

 

[GTR2EBIKE]

I wrote that poorly again. But the point was that the feeling like your tires are in molasses when street riding a dirt tire is going to affect your range the most. But so what if it does, as long as the tire you choose fits the kind of riding you'll do, street, dirt, or mixed.

The real solution of course, is a fleet of ebikes, one for street, one for dirt, etc.

Maybe in a few years i'll have that but for now I have the street tire on so i'm going to leave it. Thanks all