Help! Getting home

Simon slade

Finding my (electric) wheels
Apr 17, 2017
5
0
68
Bath
Hi All, a bit of info about rear hub drive eMTB please, as my degree is in economics, not electrical engineering! I’ve got a 12 year old Specialized StumpJumper that I had fitted, 3 years ago for my 65th birthday, with a Bafang 48v 750 watt mid drive with thumb throttle (totally illegal I know) with a 48v 17ah battery. I now live in Germany (cos of Brexit) and use it to blast around the forests over here. However, I’m 68 now and have decided to act my age and calm down a bit, especially after having bust the rear shock a couple of weeks ago (probably because I’ve never had it serviced). I’m seriously looking at getting an eFatbike with a Bafang 250 watt rear hub motor just so I can cruise through the fields and forests in comfort and be legal. My 2 questions are 1. As a hub motor Is independent of the crank how does it carry on working if/when the chain breaks? Do I need a thumb throttle? 2. Can a thumb throttle be retrofitted to a Bafang rear hub motor and if so, how? (Makes me illegal again but whatever)
 

RobN

Pedelecer
May 15, 2020
89
25
It carries on working because the motor is in the rear wheel so as long as you power it , ie using thumb throttle it will turn the wheel and propel you forward. Not sure if you can get it moving without the throttle. Someone else will be along to explain for you though.
 

RobN

Pedelecer
May 15, 2020
89
25
Im only guessing on this one but if it has the pedal assist sensor fitted on the crank and you continue to pedal (just doing the motion so to speak) minus the chain if its snapped then maybe this powers the rear wheel motor as well?
Don't quote me on that though..!
 
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mike killay

Esteemed Pedelecer
Feb 17, 2011
2,820
1,433
Im only guessing on this one but if it has the pedal assist sensor fitted on the crank and you continue to pedal (just doing the motion so to speak) minus the chain if its snapped then maybe this powers the rear wheel motor as well?
Don't quote me on that though..!
Certainly will do that on my bike,
Been there and done it, just 'ghost pedal' the motor receives the signal and operates.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
4,877
1,755
Basildon
The type of motor makes no difference. It's the motor controller that decides whether you can have a throttle or not. Choose a controller that has a throttle connector.

Most of the common controllers use a cadence sensor for pedal assist, so you only need to rotate the pedals to get power to the motor. It works even when you have no chain.
 
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