Who wants Smaller Pies?

[Bikemad]

The Magic Pie is currently available with the following size rims: 26", 28" and 700c.

Smaller sizes, such as those commonly used on BMX, folding bikes and recumbents etc. could be produced if there was enough demand for them.

If you would like GM to consider producing the Magic Pie in a smaller size, please select the size wheel you would like to see made available.
(Please answer the above Poll)

16" rims (and possibly 18" rims as well) would need to be fitted with a solid, non-pneumatic tyre or solid inner tube as there would be no way of fitting a valve.

An 18" rim for conventional tubed tyres might just be possible, but you would probably need to use one of these adapters for inflating the tyre:

[Leslie]

Some feedback.


I would vote 24" and 20 " so I just made the voting even with my vote.

A Pie on a 700c is nice.  All that torque translated to speed.  Yummy.

Really for a little dirt BMX e-bike gearless isnt all that practicle, however the Pie just looks to be good enough on a 20".

Recumbent, tandem or load carrier, shopping bike, for practical road and heavy loads use the a 24" heavy duty rim Pie would be fantastic.

There are uses for these dimentions, but how they apply to ones needs is important.  I would love a 24" Pie.

[Hyena]

I too think they should make 20" and 24"
The 24" would offer that little extra torque with the smaller rolling diametre that would be beneficial to those with hills to climb.

I think there'd also be a market for the 20" for folding and BMX type bikes but the spokes would need to be replaced by cast alloy blades like these ones.



I'd also like to see an option of different rims. My Magic Pie shipped with a 1.5" rim but my old 500w motor shipped with a 1.75" (or possibly larger, it certainly looks noticably bigger). Its something that would add little or no cost to GM but costs us alot locally to purchase a new rim and have it respoked.
Maxxis hookworms are a popular ebike tyre that are big and wide and absorb alot of the bumps, but at up to 2.5" in size I doubt they'd fit on a 1.5" rim.

[GoldenMotor]

Discuss this... and don't say I don't care for my beloved forumers.

[Leslie]

Discuss this... and don't say I don't care for my beloved forumers.

Who said this?

Where?

Anyone?

 

[Hyena]

Sweet. Is that an 18" rim ? Can it run normal tubes ?

[Bikemad]

Sweet. Is that an 18" rim ? Can it run normal tubes ?

Looks like 48 x 2.50 on the sidewall, but I can't find any information on that particular tyre size, so I'm guessing it's 16" from scale measurements of the picture, but the rim doesn't look like it's suitable for V brakes, so I presume a disc, drum or band brake will be required.

The photo definitely shows a conventional valve sticking out, so it looks like a normal tube can be fitted.

16" rims (and possibly 18" rims as well) would need to be fitted with a solid, non-pneumatic tyre or solid inner tube as there would be no way of fitting a valve.

Perhaps it was this very comment about the valve that persuaded GM into producing this rim, just just so they could prove me wrong.

Alan
 

A man who never made a mistake never made anything.

[Leslie]

 

A man who never made a mistake never made anything.

Then that makes me a walking error.

 

[Bikemad]

I've just noticed this wheel on the GM website, but I'm not convinced that the speed figures shown are correct:

eBike Speed: 25kph/24V, 33kph/36V and 45kph/48V (Based on 26" rim, 80kg rider)

Assuming this is the same motor and runs at the same rpm as the 26" version, the speed will be approximately 17kph@24V, 21kph@36V and 28kph@48V for this 16" rim.

The speed figures shown on the picture would only be correct if it can spin 62.5% faster than the 26" pie!

Yao, can you please clarify these speed figures?

Alan
 

[GoldenMotor]

Dear All,

You might find it strange, however the 16" is made to hit that speed. The windings are different, lower torque but higher speed. Go check out the Tq figs for the 16" and you shall understand!

Chopper stingray fans anyone?

[Bikemad]

Go check out the Tq figs for the 16" and you shall understand!

I've just had a quick search and couldn't find an obvious link on the site, but I did eventually find where the files for the 36V dynomometer test results were:

16" Magic Pie performance curve at 36V

16" Magic Pie performance data at 36V

The speed figures shown on the picture would only be correct if it can spin 62.5% faster than the 26" pie!

The 26" Pie wheel speed is 33.60kph@270rpm (max unloaded wheel speed)
The 16" Pie wheel speed is 37.44kph@480rpm (max unloaded wheel speed)
This means that the road speeds for the 16" Magic Pie could be even faster than the 26" version, as it can spin 77.7% faster!.

Alan
 

[ggielen]

Sounds like I want this motor instead of the one I ordered (MagicPie 'Classic') . What is exactly the RPM limiting factor? I've been reading up on brushless motors a bit, but I'm not entirely sure yet. I figured it had to do with the controller, essentially with the max speed at which it can switch the succesive coils and feed them enough current with a steep enough rate, but since the windings are apparently different I'm again clueless..

[Bikemad]

It seems confusing when they have two columns with (W) in it. What does the (r/min) column denote? I can't believe it's rpm, the numbers would make no sense. Anyone wish to translate the information?

These figures are obtained by testing the motor on a dynamometer,  A device which gradually applies a progressively increasing test load onto the wheel, whilst measuring the wheel speed, torque, the power consumed and the power produced by the wheel.

This is why the rpm is high to start with and slowly decreases as the power and torque provided by the wheel increases.

 
The "W" on the left is the power produced by the motor in Watts.
The "W" on the right is the power consumed by the motor in Watts.
The Efficiency is calculated by dividing the power produced by the power used and then multiplying by 100 to give a percentage.

e.g. If a motor consumes 600W and only produces an output of 500W, the efficiency would be 500/600*100 = 83.34%

The r/min column shown is the actual rpm of the wheel measured during the varying test load.

Alan
 

[Sangesf]

Dear All,

You might find it strange, however the 16" is made to hit that speed. The windings are different, lower torque but higher speed. Go check out the Tq figs for the 16" and you shall understand!

Chopper stingray fans anyone?

I have the electrc version of the sting Ray chopper...
I desperately NEED the 24" Magic Pie...
I would LOVE a 20" one ( but it would need to be a WIDE {4"} rim/tire cast would be awesome-- maybe I can special order one? )

[dajsino]

can I order 16" MagicPie Casted Wheel but instead of cast wheel a normal 26" bycycle wheel (with 16" MagicPie Casted Wheel motor) so I could go FASTER THAN 45 km/h ?