speed versus effort ?

[Oldgitst]

Hi all,

Only just got a bike on test and not had much time to go anywhere as yet but a quick question if I may.... IF you have full assistance setting to max and highest available gear, does an electric bike act like a road bike,,,,for example,

highest gear
highest electric assist
max speed 15mph - 17mph with leeway.....

so does the bike react in the effort required is the same peddling at 10 mph as it is at 12 / 13 / 14 / 15 to max etc etc basically the assistance becoming less and less effective the nearer you get to max speed.....

Or
is it like a normal bike that the faster you want to go the more effort is required to turn the crank ?

just curious...

cheers
og

 

[Fordulike]

Hi all,

Only just got a bike on test and not had much time to go anywhere as yet but a quick question if I may.... IF you have full assistance setting to max and highest available gear, does an electric bike act like a road bike,,,,for example,

highest gear
highest electric assist
max speed 15mph - 17mph with leeway.....

so does the bike react in the effort required is the same peddling at 10 mph as it is at 12 / 13 / 14 / 15 to max etc etc basically the assistance becoming less and less effective the nearer you get to max speed.....

Or
is it like a normal bike that the faster you want to go the more effort is required to turn the crank ?

just curious...

cheers
og

Is this bike front/rear hub motor driven or crank/central drive type?

I'll let someone else answer this one, but each type will affect what answer you get

 

[Emo Rider]

Resistance increases exponentially as the speed increases. So yes as you are approaching your cut off speed, you and the bike theoretically have to work harder. But how noticeable it is depends on the type of bike, cadence or torque, tyre type and running pressure, chain and gear condition etc.

A cadence system should be providing the same level of assistance, mechanically, right up to cut off. A torque system's assistance to cut off is determined by what gear you are in and how much resistance is on the chain between the crank and the cassette.

This is how I see it. I am sure there are some other opinions and explanations. I am here to learn like anyone else. Hope this helps, safe journey all.

 

[Oldgitst]

Is this bike front/rear hub motor driven or crank/central drive type?

I'll let someone else answer this one, but each type will affect what answer you get

rear hub driven... I would have thought more leg work required higher the speed becomes as no motor I know of remains constant bottom to top speed ??

 

[VictoryV]

Resistance increases exponentially as the speed increases. So yes as you are approaching your cut off speed, you and the bike theoretically have to work harder. But how noticeable it is depends on the type of bike, cadence or torque, tyre type and running pressure, chain and gear condition etc.

A cadence system should be providing the same level of assistance, mechanically, right up to cut off. A torque system's assistance to cut off is determined by what gear you are in and how much resistance is on the chain between the crank and the cassette.

This is how I see it. I am sure there are some other opinions and explanations. I am here to learn like anyone else. Hope this helps, safe journey all.

To be an absolute pedant... all things being equal, the air resistance increases by the square of the speed, so at 15mph the air resistance will be 9 times that of the air resistance at 5 mph, and at 30 mph it will be 36 times that at 5 mph and so on. So unless you can make up all the wind drag shortfall by yourself then your battery/motor combination is working considerably harder the fast you go

 

[Oldgitst]

To be an absolute pedant... all things being equal, the air resistance increases by the square of the speed, so at 15mph the air resistance will be 9 times that of the air resistance at 5 mph, and at 30 mph it will be 36 times that at 5 mph and so on. So unless you can make up all the wind drag shortfall by yourself then your battery/motor combination is working considerably harder the fast you go

cool, think that answered the question.... basically the effort is the same until you reach the limit of the motors ability whether 5,7 or 20 mph.... then leg power has to be used to increase any further.... so the top speed drops the more wind resistance is met....

 

[flecc]

E-bikes don't increase motor power with increasing speed once above about 8mph, and in fact a few in the past have reduced it as speed rises, since this is a requirement in Japanese law where they were made.
.

 

[Fordulike]

rear hub driven... I would have thought more leg work required higher the speed becomes as no motor I know of remains constant bottom to top speed ??

That's true, but it can also depend on how much current the motor receives, motor winding, battery voltage etc...

If for example you had a rear hub motored bike, coupled with a 48v battery, 50 amp controller and speed limited to 15.5mph.
Then due to the massive amount of torque/power available, the bike would accelerate to 15.5mph with no effort from the rider. Other than to spin the pedals to activate the PAS of course.

Just to add Oldgitst, we are then quickly getting out of legal territory with a set-up like that.

 

[Fordulike]

Oldgitst, have a little play with this motor simulator tool.

http://www.ebikes.ca/tools/simulator.html

As you change different parameters, you can actively see how they may affect how the bike performs on the road.