Pedal at friction motor speed question.

If your outrunner is hard engaged against your tire and you are pedaling at say 12 mph with your throttle matching your speed, is there much battery power used beyond idle?

Boyntonstu said:

If your outrunner is hard engaged against your tire and you are pedaling at say 12 mph with your throttle matching your speed, is there much battery power used beyond idle?

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That can vary a lot depending on your particular speed. Within a range of 1/2 mph you can go from applying a significant load to the battery to regenerating into the battery.

What is certain is that the roller hard on the tire costs a lot of energy, whether it comes from the motor or the pedals.

Chalo said:

Boyntonstu said:

If your outrunner is hard engaged against your tire and you are pedaling at say 12 mph with your throttle matching your speed, is there much battery power used beyond idle?

Click to expand...

That can vary a lot depending on your particular speed. Within a range of 1/2 mph you can go from applying a significant load to the battery to regenerating into the battery.

What is certain is that the roller hard on the tire costs a lot of energy, whether it comes from the motor or the pedals.

Click to expand...

An unloaded motor just spinning does not seem to take much power.

If I pedal at that speed, why would the motor take more power that at no load?

Boyntonstu said:

Chalo said:

Boyntonstu said:

If your outrunner is hard engaged against your tire and you are pedaling at say 12 mph with your throttle matching your speed, is there much battery power used beyond idle?

Click to expand...

That can vary a lot depending on your particular speed. Within a range of 1/2 mph you can go from applying a significant load to the battery to regenerating into the battery.

What is certain is that the roller hard on the tire costs a lot of energy, whether it comes from the motor or the pedals.

Click to expand...

An unloaded motor just spinning does not seem to take much power.

If I pedal at that speed, why would the motor take more power that at no load?

Click to expand...

Because you said "hard engaged". If you have the roller very tight it's like putting a brake on the tire. That makes it hard to pedal and it makes the motor work harder. If you want a little assist there's no reason to have it tight on the tire. If you look at the friction drives that work well on here they have either swinging or sliding mounts so the roller is only tight while accelerating.

Not sure what you mean. but I do know that on a direct drive hubmotor, 50w will eliminate cogging, if you want to run on pedal power without having to also push the motor.

So likely, you will pull less than 50 w. Even with a small battery, you can run like this two hours or more using less than 100 wh. So it's a tiny drain, well worth it to use up that way.

To eliminate the effect of the battery and motor weight, takes more. 100-150w.

dogman dan said:

Not sure what you mean. but I do know that on a direct drive hubmotor, 50w will eliminate cogging, if you want to run on pedal power without having to also push the motor.

So likely, you will pull less than 50 w. Even with a small battery, you can run like this two hours or more using less than 100 wh. So it's a tiny drain, well worth it to use up that way.

To eliminate the effect of the battery and motor weight, takes more. 100-150w.

Click to expand...

You answered my question. Thanks!

Boyntonstu said:

dogman dan said:

Not sure what you mean. but I do know that on a direct drive hubmotor, 50w will eliminate cogging, if you want to run on pedal power without having to also push the motor.

So likely, you will pull less than 50 w. Even with a small battery, you can run like this two hours or more using less than 100 wh. So it's a tiny drain, well worth it to use up that way.

To eliminate the effect of the battery and motor weight, takes more. 100-150w.

Click to expand...

You answered my question. Thanks!

Click to expand...

That is a good answer and interesting for sure for hub motors but again, if you're using friction drive and have the roller very tight I imagine it's more drain than the cogging of a small hub motor.

EVTodd said:

Boyntonstu said:

dogman dan said:

Not sure what you mean. but I do know that on a direct drive hubmotor, 50w will eliminate cogging, if you want to run on pedal power without having to also push the motor.

So likely, you will pull less than 50 w. Even with a small battery, you can run like this two hours or more using less than 100 wh. So it's a tiny drain, well worth it to use up that way.

To eliminate the effect of the battery and motor weight, takes more. 100-150w.

Click to expand...

You answered my question. Thanks!

Click to expand...

That is a good answer and interesting for sure for hub motors but again, if you're using friction drive and have the roller very tight I imagine it's more drain than the cogging of a small hub motor.

Click to expand...

Think of a motor directly geared to a geared wheel; no slippage.

When you crank the wheel to any speed and you match that speed with the motor, it should not require much power.

It is as if the motor was free running without the wheel.

Boyntonstu said:

When you crank the wheel to any speed and you match that speed with the motor, it should not require much power.

It is as if the motor was free running without the wheel.

Click to expand...

Yes, but the match must be exact. If the speed drops even a small amount, the motor will start to pick up a significant load and draw more power. And if you pedal even a little bit faster, the motor's back EMF will rise above the battery voltage and your extra pedal power will be diverted to the battery. At least that's the way it has worked with the direct drive hub motors I've used in the past.

Because there are large rolling resistance losses with a friction drive, you'll pedal harder to go slower if you leave the friction roller hard on the tire when you're not using it to drive the bike. With a friction roller drive, the best thing is to raise the roller off the tire when you don't want to run under motor power.

If you mean will the roller pressing hard on the tire cause some friction, and drag, then yeah it will.

But again, it should not take a lot of power to overcome that relatively small friction, including the motor drag. The hubmotor comparison is valid, because in both cases, the motor will cause some drag just like a direct drive hubmotor.

Or am I wrong? is there a freewheel or clutch built into it?

If you want to know how much power it takes, get a watt meter, and measure it while riding with the motor off, and the motor on just enough to make the riding easy again.

Question please? How `bout a gear on a small BLDC motor with gear covered by hard rubbery hockey puck shaped thingee bearing down instead on the wheel rim?

Object of Ebiker Lust in this case:
http://www.goldenmotor.ca/products/800-Watt-Trike-Motor.html

(Motor mounted on swiveling mount on trike front wheel frame at wheel rim height.)

EDIT: BTW, trike lacks chain and gearing: