Front wheel drive vs rear wheel drive

[DRV]

For easy of installation and weight distribution I like the front wheel drive option(Magic Pie) .
However the rear wheel option seems safer. Is it possible for the brushless motor to jam , which
would not be very pleasant if using a front drive Magic Pie hub motor .

[Bikemad]

The only moving parts between the hubmotor and the axle are the ball bearings on either side, and it would be extremely unlikely for these to jam up completely.

All wheels have bearings, but hubmotors tend to have much larger and stronger bearings than ordinary hubs, and I've never known one jam yet.

The Magic Pie uses sealed bearings to keep the grease in, and dirt and water out!

Alan
 

[Dennyb123]

I've also heard stories of forks breaking from the torque of the motor on front wheel setups. Does anyone know if this is true or not.

[DRV]

I have read that some fork designs could potential fail (aluminium) at the joint. In my case I have a 4130 steel fork/frame mountain bike.

[Hardcore]

I've also heard stories of forks breaking from the torque of the motor on front wheel setups. Does anyone know if this is true or not.

Indeed that is possible, go for rear if you really don't want torque arms but front definetely torque arms

[GM Brazil]

Do you think that the 250W mini motor used in front would need the torque arms too?

I guess that because of the freewheel the motor could have less problems with the fatigue, witch generally is the cause of the forks to fail.

[Hardcore]

250w is not enough to rip off your forks, believe me.

[GM Brazil]

Nice to know!

As I do not have a torque arm to sell I just ordered front wheel motors for the 250W model

[Leslie]

Yes weight distribution is important.

On the subject of torque arms.  For 250 watt I think a sold pair of forks and a small arm wouldn't hurt.

I would get a rear Magic Pie because I really load up my bike with heaps of shopping.

If I had a choice for a fast runnabout that is efficient and light a 700c racing bike with two mini motors may be worth a look.

A single mini motor on a 700c rim should be a little sluggish.

Wheel lock ups don't happen unless something really bad and huge happens, like hitting a bus or something falls into the wheel like a shopping bag carried on the handle bars.

It does happen but usually not due to mechanical failure.  I would want to be going 40kph and have something fly into my front hub and lock it.  But would that make any difference even if the hub was on the rear and something jammed up your front wheel?

The variables all present themselves to our imagination and run a simulation.

The a front hub in some cases is more dangerous but many ebikers who take note and do their homework swear by them.

[e-lmer]

The torque arm is not only to prevent
ripping the fork out.

When I first assembled my 500W Front wheel, I found
that the nuts kept coming loose.

The tiny bit of torque between the axle and the fork
caused the nuts to get loose over time.

I have solved this by putting a locking nut on behind
the original nut.

Nobody got hurt, but the wheel dropped out twice before
I put the locking nut on.

[Leslie]

The torque arm is not only to prevent
ripping the fork out.

When I first assembled my 500W Front wheel, I found
that the nuts kept coming loose.

The tiny bit of torque between the axle and the fork
caused the nuts to get loose over time.

I have solved this by putting a locking nut on behind
the original nut.

Nobody got hurt, but the wheel dropped out twice before
I put the locking nut on.

There are different torque arms too.

This one that transfers all the torque into rotational force and uses more fork length to absorb the torque.  The idea is to transfer this force away from the dropout in this fashion to a stronger part of the fork. The rotational arm will hold the wheel safe if the wheel nuts becoming lose.


And the other that can transfers the torque into directional force.



The ebikes.ca arm above has from my opinion has an unacceptable safety risk if your wheel nuts come lose.  
 
Unless you tighten the pivot bolt on the ebike.ca arm picture (image #2), so tight it doesnt move the arm will either push or pull the wheel out of the dropouts.  Faced the correct direction acceleration will pull the wheel into the drop-out or regen will pull it out of the dropout. All the force is concentrated right at the tip of the fork near the dropout pushing more force on the dropouts than the above arm

The pivot bolt on image #2 needs only to loosen a little to cause a risk and a large failure. Image one could have all bolts loosen and it would continue to operate way more safely.

[MasterCATZ]

where does one BUY torque arms from ?

I am planing on running 2x 90v magpie  2's on an old Mongoose NX 8.3
also what disc brakes should I get 140 or 160 ?

[muzza.au]

where does one BUY torque arms from ?

I am planing on running 2x 90v magpie  2's on an old Mongoose NX 8.3
also what disc brakes should I get 140 or 160 ?

Here is one I have from http://store.comcycle-usa.com/ProductInfo.aspx?id=4684837, although I got it from their ebay store.


As for disc brakes, if you are going to run 2 MP's, with the weight of both MP's and battery(s) I would go for the biggest breaks you can get as with all the extra weight you will need all the stopping power you can get also.

Muzza.au