Over pedalling a 36v 250 watt motor

[fangbows]

Hi my foldable 36 volt bike goes 16 mph without pedalling.

When I pedal as fast as I can with throttle on I'm going 35 mph downhill.

At that speed will it damage the brushless internal hub motor??

If not hoping to buy a 73t crankset to improve my speed, just making sure over pedalling cause no damage

 

[fangbows]

What it looks like^

 

[TForan]

35 on that ? Careful !

 

[Trail Cruiser]

No damage. It has its own internal freewheel exactly for that purpose.

 

[fangbows]

35 on that ? Careful !

I go that speed on a normal road bike too, (maximum speed I can do)

 

[fangbows]

No damage. It has its own internal freewheel exactly for that purpose.

I will trust u,
It's just It is a tiny 250 watt motor from China so I was worried it breaks when I go 35 mph , especially using a 70 teeth chainring
Maybe by overheating or friction

Another question, does the Motor basically add speed to your initial pedal speed?
Motor speed + pedal speed = final speed

Then why my 50t chainring don't feel resistance when I pedal

 

[Trail Cruiser]

The sensor detects pedal rotation only, not pedal force. You pedal hard or soft, as long as it is turning, your motor runs just the same.

It's like having an on-off switch to the motor, activated by pedal rotation.

Note, most non athletic people exert at about 40-70 sustained pedaling watts, depending on how fit you are.

 

[fangbows]

The sensor detects pedal rotation only, not pedal force. You pedal hard or soft, as long as it is turning, your motor runs just the same.

It's like having an on-off switch to the motor, activated by pedal rotation.

Note, most non athletic people exert at about 40-70 sustained pedaling watts, depending on how fit you are.

I only using the throttle mode instead of the pedal assist
So the sensor should not matter?

My question is, by adding a giant chainring (70t), do you increase the maximum speed only with throttle?

 

[rich c]

I really doubt if the throttle is doing anything when you are pedaling downhill. All controllers have a max current setting to the motor. Same thing goes with riding on flat ground. It will only send so much current no matter what the pedals are doing. With a bigger chainring, you are putting in the effort to go over what the motor sees from the controller. Hope you never have to quickly stop at that speed with rim brakes on little wheels! REALLY dangerous!

 

[fangbows]

I really doubt if the throttle is doing anything when you are pedaling downhill. All controllers have a max current setting to the motor. Same thing goes with riding on flat ground. It will only send so much current no matter what the pedals are doing. With a bigger chainring, you are putting in the effort to go over what the motor sees from the controller. Hope you never have to quickly stop at that speed with rim brakes on little wheels! REALLY dangerous!

So with a bigger chain ring, the motor is not doing any work at high speeds? How do you hack the motor so it does maximum work while your pedalling as hard as u can

 

[Bruce Arnold]

So with a bigger chain ring, the motor is not doing any work at high speeds? How do you hack the motor so it does maximum work while your pedalling as hard as u can

The throttle will send maximum power to the motor when you have it wide open regardless of how you pedal. If you pedal, you are adding that amount of force to the hub so you go faster. Experiment with this and you'll see for yourself. Try throttle only, then throttle plus light pedaling, medium pedaling, and hard pedaling. On a level surface to get a real feel for the thing.

Understand that all jurisdictions have limits to how fast the bike can go with the throttle. In the EU, I believe it is 25 kph. In the USA, it's 20 mph in most places. With a throttle plus pedal combination, when you get past that limit, then the throttle is no longer adding anything and it is all on the pedals.

A bike with a torque sensor will increase the amount of power sent to the motor when you pedal harder. That's what allows most speed pedelecs to use pedal assist to get up to 28 mph.

 

[Trail Cruiser]

I only using the throttle mode instead of the pedal assist
So the sensor should not matter?

My question is, by adding a giant chainring (70t), do you increase the maximum speed only with throttle?

you can lift the ebike and full throttle it to see the top speed. That will be the unloaded speed. The loaded speed will be anywhere from 60-80 %.

The easiest hack to increase speed is by using higher voltage but you run the risk of burning your electricals.

 

[Trail Cruiser]

I only using the throttle mode instead of the pedal assist
So the sensor should not matter?

My question is, by adding a giant chainring (70t), do you increase the maximum speed only with throttle?

The motor will run out of steam (red lining) at maybe about 20 mph depending on the internal ratio. Using 70 teeth chain ring will not change the top speed of the motor.

Above the top speed of the motor, all the effort is done by your legs (none from the motor).

 

[TForan]

I go that speed on a normal road bike too, (maximum speed I can do)

I would think it gets a bit twitchy with those little wheels and tires. Have fun!

 

[rich c]

So with a bigger chain ring, the motor is not doing any work at high speeds? How do you hack the motor so it does maximum work while your pedalling as hard as u can

You keep talking about the motor and the chainring. The motor spins up to the amount of current sent to it. Want high speed? Buy a 52 volt battery, a 750 or 1,000 watt motor, buy a 35-50 amp controller, then you can get the speed you want. If you spend $1000+, you can probably get 40-45mph on level ground. You still have the aerodynamics of a brick as you sit on the seat.

 

[harryS]

Fangbows, your motor has a clutch that allows the wheel to spin faster than it, so you can go a lot faster than what a little motpr on a 20" bike will go. If you are using throttle at 35 mph, you're just wasting power. The motor will be spinning at its max unloaded rate, but will not help at all, because it is still slower than 35 mph. The clutch allows this to happen.

I often pedal my bike at a speed faster than the pedal assist I am using, so the same thing happens. Wheel spins faster than the motor, but the cluthc allows this. Since the motor is now spinning without a load, the current draw is quite low, maybe 1-2 amps. I can see the watts drop to 20-40 watts.

 

[rich c]

Fangbows, your motor has a clutch that allows the wheel to spin faster than it, so you can go a lot faster than what a little motpr on a 20" bike will go. If you are using throttle at 35 mph, you're just wasting power. The motor will be spinning at its max unloaded rate, but will not help at all, because it is still slower than 35 mph. The clutch allows this to happen.

I often pedal my bike at a speed faster than the pedal assist I am using, so the same thing happens. Wheel spins faster than the motor, but the cluthc allows this. Since the motor is now spinning without a load, the current draw is quite low, maybe 1-2 amps. I can see the watts drop to 20-40 watts.

Do direct drive hub motors also have a clutch?

 

[Trail Cruiser]

Do direct drive hub motors also have a clutch?

No.

 

[slomoshun]

Do direct drive hub motors also have a clutch?

As Mark, said, no. That is why they cog.