Front or rear MP? How regen works for you?

[GM Brazil]

Hi!
I was looking for an eBike kit solution for months now, and I'm very happy to find the Magic Pie and Golden Motor.

I have some doubts about the system. First, it is better to have the front or rear motor? I imagine that using it on the front I have a better weight distribution, as the battery goes in the back, and is also better for the regen. So, why use put everything in the rear?

Second, about the regenerative system. Does it works just when I use the powerbrakes (or as I am planning to use, with a dedicated button) or it starts to work when I stop throttling?

And an extra: the cruise control use the regenerative system to keep the speed on downhill automatically or I need to keep pressing and releasing the buttons/powerbrake to put it on and off???

Why is so expensive to send it to Brazil, there is better (cheaper) shipment options?

Sorry any problemns with my english, and thanks!

[GM Brazil]

About the first...

I found this on GM Canada:

Wheel hub motor - Determines how fast you can go on level ground, against wind or uphill.

Although mounting an electric hub wheel to the front of your bike does seem a little easier, most bicycles sold today have thin front forks, suspension forks or even alluminum forks. These forks most likely are not strong enough to handle the stress of full throttle acceleration or the stress of deacceleration caused by braking or regenerative braking. The constant rocking back and forth can break them off or the constant back and forth twisting of the forks at the nuts that tighten the wheel on can tear the ends of the forks off. Losing your front wheel at a high speed while in traffic can be devastating and even tragic. We recommend using rear wheel upgrade kits unless you are sure your front forks can handle it.

[Bikemad]

Hi and welcome GM Brazil,

The choice between front or rear motor is usually decided by ease of fitting and the rider's personal preference.
If your rear wheel is currently fitted with 8 or 9 speed cassette gears, it is not possible to simply transfer this over to the Magic Pie.
Therefore fitting a front Magic Pie would be cheaper and easier to install, whilst also allowing you to retain all of your current gears.
This is not a problem, provided the front forks are not aluminium. Also, the drop-outs must be sufficiently strong enough to withstand the torsional load being passed through the wheel's axle, otherwise a separate torque arm will need to be fitted. It would be a good idea to fit a torque arm anyway, just to play safe. (Belt and Braces!)
(A standard front wheel does not apply any discernible torsional force to the axle during braking!)
The torsional axle force is a direct result of motor torque under power and regenerative braking, and is additional to normal braking forces!
Please note, the normal braking forces will also be greater due to an increase of the vehicle's mass and speed!
You are correct in assuming a front mounted Magic Pie will give a better weight distribution.

With the rear Magic Pie, it would provide more traction on the driving wheel for hill climbing on slippery surfaces etc. and a shorter cable route for the current flowing between the battery and the controller/hub motor.
Regen (which is operated by the power breaking switches on the brake levers) should work just as well on the rear as it would on the front, but with less chance of losing the front end (and your steering) while braking into corners at speed on loose surfaces.
A rear hub motor should also be better for wheelies , but worse for stoppies! (nose wheelies) 

The cruise control only regulates the power to the motor, and does not apply any braking effect if the set speed is exceeded, so you would need to use your regen or brakes to maintain a slower set speed going down steep hills.

Check this post for additional suggestions for operating regen.

If you can purchase from one of the GM Authorised Dealers instead of direct from China, you should be able to save on shipping.

Alan
 

[GM Brazil]

Thank you very much Bikemad!!

I think that for safety I'll use the rear motor. The post you've linked to me answers perfectly what I need to know about the regenerative use, thanks! I liked this setup

My advice would be to ignore the throttle switch and simply rewire the two brake switches so they are connected in series instead of parallel.
When wired like this, the regen will only work when both brakes are applied together. This way you can use either the front or back brake independently without the regen cutting in, but when you do need to stop quickly, it will automatically be there to assist you.

ps.: The regenerative really charges uo the battery or it just uses the motor as an EM brake?

I tried the resselers, they all do not have the Magic Pie, and the canadian do not sell outside Canada. This will be my first ebike and the GM direct shipment price is scary.

And there is discrepancies on prices, if you go to the DIY kits page and "build" a kit on that table the prices are very different from those on the Magic Pie kit page, and more, when I change do Brazil the shipment still US$115 but the kit itself is more than a US$100 more expensive, I do not know why...

As this is for the next year (I'm planning to have enough money buy @ 02/2010). I'm trying to convince friends to buy togheter and have a better discount with sea shipment, but everyone whant to see by themselves before buy

Thanks, again!

[Bikemad]

GM Brazil,

The Magic Pie's regen should charge the battery.
Wayne's bike has two 48V HBS hub motors fitted and his Cycle Analyst showed a charge of about 2000 Watts under hard braking.
See this post for more details on Wayne's bike.

Check out this post regarding shipping.

Alan
 

[GM Brazil]

Thank you again Bikemad!

I follow the tip of 5tonica (by PM) to try some european resselers, but is much more expenseive than buying directly from MP. I would like to became a resseler here in Brazil, but for the next year, at least, I'm sure that I will not have the money to start a business here, lol.

The USA dealers just don't have the MP on the websites, and I don't know how much could be to buy from them, Canada does not delivery here. I found some kits on mercadolivre (kind of ebay for SouthAm) but no MP and just some suspicius bad looking/quality hub motors all with lead acid batteries (22,5kg just them!!!!) and just a little bit cheaper tham the complete MP kit from GM! I sure I can find a better deal with GM.

I just need the MP kit, 48v12A lipo batt and the rak. I'll have time to search and/or wait for better opportunities as I'll just buy next year. And  I'm sure that I want GM products.

[GM Brazil]

Thank you Gary,

I did find a way to solve this issue! I sent you a PM about it.

[GM Canada]

Thank you Gary,

I did find a way to solve this issue! I sent you a PM about it.

I did receive your private emails, but did not respond as I feel your questions are better answered in the public forums, I have nothing to hide 

Glad to hear you were able to get things sorted out.

Gary

[GM Brazil]

Yes, I agree with you. But I need some degree of secret, is  very slow and annoying to open a company here and I would not like to someone (with a company already working) to get this great opportunity before me!