Bargain on eBay

[patpatbut]

Hi guyz

Found this

http://bit.ly/1a2UN2W

Looks like a twin drive bike and costs only 350

Do you know what is the motor at the rear?

Pat

 

[Deleted member 4366]

That's the battery in the back wheel believe it or not! The motor is in the front wheel.

 

[patpatbut]

Oh yea. I did wonder where is the battery

 

[OxygenJames]

Yeah imagine what having that mass flying around what that centrifugal force is going to do to the handling..... you probably dont want to know.

 

[cwah]

High mass as centrifugal should increase stability isn't it?

Maybe not as simple to turn, but I'd imagine it would have the same effects as moped with heavy tyres?

 

[Deleted member 4366]

Good point, Cwah.

I was thinking about a single cell in the hub. They rotate at constant speed in the wheel, but when the bike is also moving, the cell is constantly accelerating and decelerating, which must put a terrible strain on it and the rest,then you can add the centrifugal force as well.

 

[eHomer]

Are we sure the battery is in the wheel ?

The listing contains the sentence "The bicycles frame is thicker and more robust to suit foldability and to accommodate the battery and motor which is built into the frame. "

Agreed, it's very vague, since the motor can't be in the frame, but that fat crossbar could have the innards of a bottle battery in it, maybe...

If the battery was indeed in the rear hub, how could the thick main power leads be brought out ? Wouldn't they be too thick for the hole in the axle ?

I guess it could conceivably be engineered like an old cyclemotor petrol engine, where the large hub remains stationary and the wheel runs around the outside, but it seems quite a complication for the limited advantage (if any ?)

 

[Deleted member 4366]

Definitely in the back wheel. We discussed it about a year ago in a previous thread.

 

[shemozzle999]

I doubt that the cells rotate and replacement batteries are still available:

http://www.alibaba.com/product-gs/614175669/electric_bicycle_battery_36V10Ah_rear_wheel.html

Installed with a Bafang crank drive it could make quite a stealthy ebike.

 

[eHomer]

Well that shows my ignorance on the subject...

I'd have thought there were so many practical reasons against it being any good there.

Not sure about the stealth either, it looks like a bl**dy great big direct drive motor, especially in this instance, with the legal looking one on the front.....

 

[shemozzle999]

I'd have thought there were so many practical reasons against it being any good there.

Not sure about the stealth either, it looks like a bl**dy great big direct drive motor, especially in this instance, with the legal looking one on the front.....

Agreed eHomer not ideal, mainly the need of on board charging only also not suitable for high power user requirements ( unless you fit 2) but with paniers installed to cover the hub could be a simple well balanced installation.

 

[eHomer]

Yes Shemozz, my first ebikes years ago had permanently installed batteries, and I hadn't appreciated the advantage of being able to quickly remove them with modern lithium packs.

Admittedly, that usually makes them easier to nick in a non locking carrier, but on balance, for me, it's much more usable. Easier to bring in to the house in the depths of Winter too.

Another attraction of the crank drive for me would be to reduce the weight over the rear wheel and give the opportunity of an internal hub gear. It seems such a waste to put a fairly restricted battery in there.

I'm still avidly following all the threads on the BB02, it's such a neat looking bit of kit, even with the reservations about gear changing.

 

[Deleted member 4366]

Y

I doubt that the cells rotate and replacement batteries are still available:

http://www.alibaba.com/product-gs/614175669/electric_bicycle_battery_36V10Ah_rear_wheel.html

Installed with a Bafang crank drive it could make quite a stealthy ebike.

The cells rotate with the wheel.

At the bottom they move in the opposite direction to the bike, so rotation speed is subtracted from bike speed and real speed is slow. At the top of the wheel, their rotation speed is added to the speed of the bike, which means that for each rotation they go from slow to fast and back to slow again. Acceleration and deceleration cannot be achieved without force, so each cell will experience a forward and backwards force during each rotation similar to the force in a control as a piston goes up and down. Imagine each cell being the piston.

 

[shemozzle999]

They look permanently attached to the hub shaft otherwise you would require slip rings to make the electrical connections?:

http://www.alibaba.com/product-gs/533321406/36v_8ah_10ah_wheel_hub_battery.html

 

[Deleted member 4366]

They look permanently attached to the hub shaft otherwise you would require slip rings to make the electrical connections?:

http://www.alibaba.com/product-gs/533321406/36v_8ah_10ah_wheel_hub_battery.html

Good point!