Torque sensor with hub motor?

[Cavemann]

Hi everyone,

I'm bulding an e-bike out of a Pinnacle Lithium, with a Bafang hub motor, kt controller etc.
I've previously tried out an e-bike with pas cadence sensor and found it a bit anoying when standing/hill starts.
I've heard that pas torque sensors give a more natural feel and presumably would improve the standing/hill start feeling(?)

So, can anyone advise if it's possible/sensible to use a pas torque sensor with a DIY hub motor bike?

 

[saneagle]

Hi everyone,

I'm bulding an e-bike out of a Pinnacle Lithium, with a Bafang hub motor, kt controller etc.
I've previously tried out an e-bike with pas cadence sensor and found it a bit anoying when standing/hill starts.
I've heard that pas torque sensors give a more natural feel and presumably would improve the standing/hill start feeling(?)

So, can anyone advise if it's possible/sensible to use a pas torque sensor with a DIY hub motor bike?

It is, but rather than go by what you've heard, try the KT controller first, as you already have it. Most of those guys preaching about torque sensors have never tried a KT controller.

After-market controllers with torque sensors can be a bit crude, and the torque sensors are relatively heavy. You'd have to change to a square taper crankset too.

IIRC, Woosh sell a hub-motor kit with a torque sensor arrangement. I can't remember if they sell the torque sensor and controller separately.

 

[Nealh]

If you want natural feel, ride a normal bike with no motor .
It's all pure nonsense which PAS motorised bike is more like a natural bike, answer none becasue they all have motor power.

 

[Woosh]

IIRC, Woosh sell a hub-motor kit with a torque sensor arrangement. I can't remember if they sell the torque sensor and controller separately.

we can't supply components (motor wheels, batteries, controllers, LCDs, sensors, cable looms etc) to individuals.
That would make support a nightmare.
We supply professionals with parts for out of warranty repairs though.

 

[Bikes4two]

It is, but rather than go by what you've heard, try the KT controller first, as you already have it. Most of those guys preaching about torque sensors have never tried a KT controller.

I am a great fan of the TSDZ2 mid drive system which is a torque sensing controller/motor as to me the assistance delivers power to the bike in an as near similar way as if I'd had younger legs transplanted .

Having said that I did fit a KT controller to a Pendleton Somerby (rear hub motor) back in July 2020 (link) and as I remember it, the ride feel was for me, much improved over the replaced cadence sensing controller.

I was not riding ebikes at that time so a direct comparison with a TSDZ2 wasn't on the cards and the Pendleton was sold on, but should I ever get to install a hub motor, I'd be very happy to give the KT kit a go, so as @saneagle says, fit the KT controller and see what you think

 

[Cavemann]

It is, but rather than go by what you've heard, try the KT controller first, as you already have it. Most of those guys preaching about torque sensors have never tried a KT controller.

After-market controllers with torque sensors can be a bit crude, and the torque sensors are relatively heavy. You'd have to change to a square taper crankset too.

IIRC, Woosh sell a hub-motor kit with a torque sensor arrangement. I can't remember if they sell the torque sensor and controller separately.

Thanks @saneagle.
You mean try the KT controller with a cadence sensor right? ...any advice on a good cadence sensor to get, or are they all similar?

 

[Cavemann]

If you want natural feel, ride a normal bike with no motor .
It's all pure nonsense which PAS motorised bike is more like a natural bike, answer none becasue they all have motor power.

I do have a normal bike, which I use regularly and enjoy very much.
In addition to my normal bike I'm building an e-bike and my post was seeking advice on PAS sensors with a DIY hub motor conversion. This is the conversion kits forum right?

 

[Cavemann]

I am a great fan of the TSDZ2 mid drive system which is a torque sensing controller/motor as to me the assistance delivers power to the bike in an as near similar way as if I'd had younger legs transplanted .

Having said that I did fit a KT controller to a Pendleton Somerby (rear hub motor) back in July 2020 (link) and as I remember it, the ride feel was for me, much improved over the replaced cadence sensing controller.

I was not riding ebikes at that time so a direct comparison with a TSDZ2 wasn't on the cards and the Pendleton was sold on, but should I ever get to install a hub motor, I'd be very happy to give the KT kit a go, so as @saneagle says, fit the KT controller and see what you think

Thanks @Bikes4two .
Your Pendleton project looks great. I've picked up lots of good info reading through the posts.
Now I'm even more confused though. Reading what you and @saneagle have said, and references in your Pendleton posts ("PAS - Without PAS "), is the implication that the KT controller doesn't need a PAS sensor? ...or am I missinterpretting it?

 

[Bikes4two]

@Cavemann - you do indeed need a Pedal Assist Sensor (PAS)

 

[saneagle]

Thanks @Bikes4two .
Your Pendleton project looks great. I've picked up lots of good info reading through the posts.
Now I'm even more confused though. Reading what you and @saneagle have said, and references in your Pendleton posts ("PAS - Without PAS "), is the implication that the KT controller doesn't need a PAS sensor? ...or am I missinterpretting it?

I think you are misunderstanding something. What I said is that it doesn't need a torque sensor because it works pretty nicely with a normal cadence pedal sensor. I would never go without a pedal sensor. If you didn't buy one with your kit, any normal magnet disc type will work, but best avoid ones with 12 magnets. For some strange reason people seem to ha e trouble getting the 12 magnet ones to work.

 

[Cavemann]

@Cavemann - you do indeed a Pedal Assist Sensor (PAS)

Understood. Thanks for clarifying

 

[Cavemann]

I think you are misunderstanding something. What I said is that it doesn't need a torque sensor because it works pretty nicely with a normal cadence pedal sensor. I would never go without a pedal sensor. If you didn't buy one with your kit, any normal magnet disc type will work, but best avoid ones with 12 magnets. For some strange reason people seem to ha e trouble getting the 12 magnet ones to work.

Thanks for the advice, much appreciated. I'll do some research on a cadence sensors with more than 12 magnets.

 

[Cavemann]

Project so far. Once I get the PAS working I intend to remove the twist throttle.
It currently max's out at 22MPH, so my next task will be to figure out how to restrict it to 15.5MPH...

 

[saneagle]

Thanks for the advice, much appreciated. I'll do some research on a cadence sensors with more than 12 magnets.

You need less than 12 magnets, like 8 or 10.

 

[Nealh]

If your BB is hollowtech or sram equivalent then the best option is to by a BZ10C Pas combo.

 

[Cavemann]

If your BB is hollowtech or sram equivalent then the best option is to by a BZ10C Pas combo.

Thanks @Nealh. Those are harder to get in the UK, but I managed to get one on a longer leadtime and happy to wait as I'd rather go with a recomended one. Much appreciated.

 

[peterjd]

Thanks @Nealh. Those are harder to get in the UK, but I managed to get one on a longer leadtime and happy to wait as I'd rather go with a recomended one. Much appreciated.

Just to answer your original question - yes it is possible to have a torque sensor with a hub drive since my Decathlon Riverside 500E has it (possibly combined with some cadence sensing). The sensors are housed in the bottom bracket with the hub in the rear wheel. I like the overall effect particularly in starting from a stop but it is not perfect and can produce a 'surge' effect in some circumstances. Since the bike is under an extended warranty I don't intend investigating further. Good luck with your project. Peter