Question about the Magic Pie conversion kits and their axle

[Triomoto]

Hi,


I was hoping to use an electric conversion kit to convert a recumbent tricycle. However, the dealer informed me that the axle for the wheels already in place was 12 mm, instead of the "10 mm standard." What are the standards for the wheels Golden Motor offers and is there any option for a 12 mm compatible wheel?


Thanks!!

[Bikemad]

Hi andto the forum.

Most of the GM hubmotors use a 14mm axle with 10mm flats, but the Cassette version of the Magic Pie Edge uses the smaller 12mm axle with 10mm flats.

It should be possible to mount either of these axles in a 12mm wide slotted dropout, but you would need to use a pair of substantial torque arms to transmit all of the torque between the axle and the frame.

If it's a tadpole trike (and you are planning to use a rear motor) you will need to make sure that the frame has conventional slotted dropouts and not just a single hole for a "thru-Axle".

Alan
 

[Triomoto]

Thank you for the response!


We were planning on converting the front wheels in order to attach other materials to the back, is there any option in regards to that?



Thanks again.

[Bikemad]

If the front wheels are only mounted using one side of the axle, I would not recommend installing a standard hubmotor using this method of attachment due to safety concerns.

Also, using a pair of hubmotors with small diameter tyres would produce a lot of noticeable drag when you were pedalling without motor assistance, and they would produce well over twice the amount of regenerative braking current (compared to a single, larger diameter rear wheel) which the battery may not be able to handle (especially with the higher downhill speed of a recumbent).

If you can provide the make and model of trike, it would be a lot easier to offer useful advice and/or make further suggestions. 

What exactly do you mean by "attach other materials to the back", and how/why would a rear hubmotor prevent you from doing this?

Alan
 

[Triomoto]

Thanks for the response,


The recumbent tricycle we're modifying is a HP Velotechnik Scorpion FS 26

here is the link: http://www.hpvelotechnik.com/produkte/scorpion_fs26/index_e.html (sorry for not providing it sooner)
here is more technical data regarding the trike: http://www.hpvelotechnik.com/produkte/scorpion_fs26/technik_e.html

As for the back, while it is more speculation, we are also planning to attach an additional gas motor to further increase the speed.
My supervisor is, in his own words, committed to the hub motors remaining on the front wheels. With regards to the battery, would a larger capacity battery be able to handle the braking current? If not, what component in the braking system would be too much for the battery to handle?




Thank you for your help!!

[Bikemad]

If a pair of 20" Magic Pies were fitted to the front (which I would not recommend due to the single end axle fixing requirement) the trike would only have a maximum speed on the flat (without pedalling) of ~35km/h (~21mph).

However, fitting a single 26" rear Magic Pie would actually produce a higher maximum speed on the flat (without pedalling) of ~45km/h (~28mph).

I think the single rear hubmotor is the simplest and most obvious choice, which is probably why the manufacturer has opted for a rear motor on their own electric version. Other practical alternatives include a mid drive motor or a crank mounted motor.
The crank mounted motor would probably make the trike more prone to tipping under heavy braking due to the centre of gravity being further forward.

If you wanted more speed, you would simply need to use a higher voltage battery along with a higher voltage external speed controller, as the internal controllers are only suitable for 24,36, or 48 volt batteries.
With a 72V battery pack (and a suitable 72V external controller) it should be capable of ~65km/h (~40mph) with a 26" rear hubmotor. 

This video shows the Outrider 422 Alpha trike exceeding 85mph on a runway!

If your supervisor really insists on the hub motors remaining on the front wheels, you will have to find a hubmotor manufacturer who can supply a pair of single sided axle mounted 20" wheels which have been specifically modified for a much higher rpm, in order to obtain the higher speeds you appear to be looking for, as the Magic Pie is not designed or meant for single sided axle fixings.

Check out this YouTube video showing what a high powered RWD electric trike can do.

A larger capacity battery may well be able to handle the braking current of two motors, but to me this is irrelevant, as a slower dual front wheel drive system (combined with a gas engine to compensate for them) seems a bit pointless.

Why would you want to use three motors when one is sufficient?

If you do some more research of your own, I'm sure you will come to the same conclusion.

Alan