Looking for information on the Magic Pie edge cassette version of the DD motor

[Pbert]

Hi,

I am new to the ebike scene and have been reading for a couple months now.  I've narrowed down the candidate for my first build to be the Magic Pie edge rear motor but there is one piece of information that I am missing before going ahead.  I've been looking for people who have ordered the edge with the cassette in the rear in order to install up to 10 gears.  Was wondering how their experience was.  Also if anyone has ordered through the goldenmotor.ca site to let me know how they managed to specify the freehub version of the kit instead of the freewheel version because I did not find any options to specify this.

Thanks.

[Bikemad]

Hi Pbert andto the forum.

I received a pre-production cassette version of the Magic Pie Edge back in September 2015 and I was very concerned about the small amount of surface area available on the freewheel end of the axle where it pressed against the torque washer:



After dismantling the freehub unit, I discovered there was no internal spacer between the inner tracks of the two bearings in the centre of the freehub unit, so simply adding an additional spacer between the freehub outer bearing and the axle washer to withstand the compression load of the fully tightened axle nut was not possible.
I therefore suggested that the axles could be modified to allow a nut to be threaded further onto the axle and further inside the freehub locking nut to maintain the correct axle width to suit the standard 135mm wide rear dropout:




However, I believe that the axle was not actually modified, but an extra inner nut was simply added to the existing axle to withstand the compression force of the outer axle nut.
Unfortunately, the additional thickness of the nut increases the overall mounting width of the axle by ~7mm:





I was also concerned that the tabbed washers would not be able to withstand much torsional force from the axle due to the reduced size of the axle (12mm instead of 14mm) but still with the same 10mm flats.
It is also worth noting that the dropouts on most modern bike frames are not actually deep enough to allow the tab of the torque washers to even locate within the dropout slot:



On my front mounted Smart Pie, I decided to bend the tabs back on themselves so that they would actually locate inside the dropout slot:



I suggested that it should be possible to modify the existing axles (or produce a new axle) along with a dedicated torque arm that would easily transmit all the motor torque under full load (and during regenerative braking) directly to the frame:





Unfortunately, GoldenMotor decided not to adopt my proposed torque arm system because they were concerned that it would not be compatible with all the different frame types. 

If you decide to fit the cassette version, (which I don't think GM Canada have in stock) and your frame can accommodate the additional 7mm axle width of the washer without having to be forced apart excessively (which my aluminium frame wouldn't) then I strongly advise that you also fit a pair of decent torque arms to prevent the smaller diameter axle from spinning.

Alan
 

[Pbert]

That's more than I could have hoped for as far as information and detailed experience of using the cassette version of the edge.  Thank you very much for that response and the time to go into the details.  Based on this and info that Gary from Golden Motors Canada had provided me, I will go with the freewheel version.  My initial idea was that I wanted a single large chain ring in front, in order to get rid of the derailer and shifter, but I still wanted to be able to pedal up hills and also pedal at high speeds, so I wanted to fit a chainring with a large range of teeth in back.  In the end I will go with a 7 freewheel in back, 11-34T if I can find it (difficult) and a 50 or so tooth in front.  Thanks again Alan, glad to have found this place. Have a good one.