Torque sensors and where to buy ?

[SteveDillon]

Hi,
having rented an ebike recently, I'm converted. The bike we rented was a crank driven (using Bosch), but I'm thinking of converting my existing non electric tourer. The centre drive conversion options look cumbersome, so I've been looking at a front drive option but with a bottom bracket torque sensor rather than a pedal sensor (to mimic the Bosch).
Unfortunately I cannot find any UK (or European) supplier of the requisite sensors / controllers (even though i think THUN is German). The best website by far is the Canadian Grin Tech site.
Am I missing something ? Is there a reason why conversion components such as the Torque Sensor and controller are (apparently) not available this side of the pond.
I came across a similar post from 2016, but the poster managed to get hold of the sensor without finding a retailer.

I'll copy this post into the conversion kit forum.
Thanks in advance for any help.

 

[Woosh]

is something like this you are looking for?
woosh tskit

 

[vfr400]

Torque sensors on hub-motors offer very little advantage. In fact some are terrible. If you want a hub-motor a normal cadence sensor and a Kunteng controller will give you a nice riding experience.

There are a lot of drawbacks and potential risks when installing a front hub-motor. A rear one is always better unless you have hub gears.

 

[JuicyBike]

Torque sensors on hub-motors offer very little advantage. In fact some are terrible. If you want a hub-motor a normal cadence sensor and a Kunteng controller will give you a nice riding experience.

There are a lot of drawbacks and potential risks when installing a front hub-motor. A rear one is always better unless you have hub gears.

Agreed that some are indeed awful. We tried at least 10 before finding the one that produced excellent results when matched with the correct software.
I recommend the OP take a look at the Sempu range. Endless sphere forum has lots of information.

 

[Force_Measurement]

• Step 1: Understand your application and what you want to measure or control. Firstly, understand your application and define the type of torque you want to measure — reaction torque or rotary torque?
• Step 2: Define the sensor mounting characteristics and its assembly. How will you be mounting the sensor? (Flange to flange, square drive, shaft to shaft, hex drive, etc.) Will you be using this clockwise, counterclockwise, or both?
• Step 3: Define your minimum and maximum capacity and key requirements. Be sure to select the capacity over the maximum operating torque and determine all extraneous load (side loads or off-center loads) and moments prior to selecting the capacity. Also, what is your max RPM required? Do you need to measure speed and angle position?
• Step 4: Define the type of output your application requires. Some sensors outputs a mV/V signal, which can be paired with an amplifier for up to ±10VDC, while other non-contact rotational sensors will provide ±5VDC output . So, if your PLC or DAQ requires analog output, digital output or serial communication, you will need a torque sensor amplifier or signal conditioner. Make sure to select the right amplifier as well as calibrate the entire measurement system (sensor + signal conditioner). This turnkey solution translates into more compatibility and accuracy of the entire torque measurement system.

Torque Sensors | Torque Transducers | FUTEK

Torque Sensor is defined as a transducer for measuring torque and converts it into an electrical output signal (aka Torque Transducers or Torque Cell). There are two main types of torque sensors: Reaction Torque Sensors and Rotary Torque Sensors.

www.futek.com

 

[Nosweat]

I'm on my second TS kit from Woosh now. Not that there was anything wrong with the first thugh, quite the reverse. The first one went on my bike and is so brilliant that my wife wanted one for her bike too. I have a front hub, she has a rear hub motor. So much nicer than a cadence sensor we both feel.

 

[06thundertrucker]

I'm on my second TS kit from Woosh now. Not that there was anything wrong with the first thugh, quite the reverse. The first one went on my bike and is so brilliant that my wife wanted one for her bike too. I have a front hub, she has a rear hub motor. So much nicer than a cadence sensor we both feel.

I am looking at getting the same kit from Woosh. Could you please tell me (if you know)
1) Is there a possibilty to run the crankset with more than one chainring and a front mech?
2) What have you found to be the pros/cons for having a front or rear drive.

Many thanks
Tim

 

[Woosh]

1) Is there a possibility to run the crankset with more than one chainring and a front mech?

that may be possible because the TS hub kit uses a standard 5 bolt ring but I have never tried it. I will check the BCD and the diameter of the controller box behind the ring tomorrow and let you know.

Best regards

Tony

 

[Nosweat]

Hi Tim you would need to speak to Woosh to confirm but I doubt you could run the crankset with more than one chainring. However, if you need a wider range of gears there's nothing to stop you having rear hub gears such as the Shimano Nexus unless you are wedded to derailleurs or hate hub gears.

Also bear in mind that due to the assistance you suddenly find yourself having in low gears, and the maximum cruising speed being possibly limited to 15m[pg depending on whether you want to put in all the power from there on upwards, you may well find that with an ebike you don't need as wide a range, or as many gears as you would on a non-assisted bike.

A rear hub motor possibly feels a bit more "natural" than a front hub since it's where the power normally goes on a pushbike but it makes the back end of an ebike very heavy and may be more likely to puncture and harder to repair. It alows you to fit a front hub dynamo (sounds silly, but you probably can't use the motor battery to power your lights so need either AA battery powered lights or a front hub dynamo). Conversely a front hub gives the slight impression of "pulling" you along though it's not unpleasant, just a bit strange at first. On gravel going uphill you will struggle to get grip so not advised to try cycling up a steep gravelly slope with a front hub. It also makes the front wheel much heavier on potholes though I haven't noticed any unpleasant centrifugal effects that some have mentioned. Ease of removing the front wheel, and ease of conversion are two of the biggest pluses. And your front forks must be steel (or fit ugly torque arms with aluminium forks).

If you want to easily convert an existing bike into a robust road going commuter then front hub is the way to go; if you don't mind a derailleur and fancy a bit if off roading a rear hub may be better.

Don't know if Woosh are selling the torque sensor yet with rear hubs (check with them) but for my bike I got a front hub motor XF07 and my wife's bike is a Santana3 that Woosh built to order with a torque sensor and rear hub motor.

 

[06thundertrucker]

Hi Tim you would need to speak to Woosh to confirm but I doubt you could run the crankset with more than one chainring. However, if you need a wider range of gears there's nothing to stop you having rear hub gears such as the Shimano Nexus unless you are wedded to derailleurs or hate hub gears.

Also bear in mind that due to the assistance you suddenly find yourself having in low gears, and the maximum cruising speed being possibly limited to 15m[pg depending on whether you want to put in all the power from there on upwards, you may well find that with an ebike you don't need as wide a range, or as many gears as you would on a non-assisted bike.

A rear hub motor possibly feels a bit more "natural" than a front hub since it's where the power normally goes on a pushbike but it makes the back end of an ebike very heavy and may be more likely to puncture and harder to repair. It alows you to fit a front hub dynamo (sounds silly, but you probably can't use the motor battery to power your lights so need either AA battery powered lights or a front hub dynamo). Conversely a front hub gives the slight impression of "pulling" you along though it's not unpleasant, just a bit strange at first. On gravel going uphill you will struggle to get grip so not advised to try cycling up a steep gravelly slope with a front hub. It also makes the front wheel much heavier on potholes though I haven't noticed any unpleasant centrifugal effects that some have mentioned. Ease of removing the front wheel, and ease of conversion are two of the biggest pluses. And your front forks must be steel (or fit ugly torque arms with aluminium forks).

If you want to easily convert an existing bike into a robust road going commuter then front hub is the way to go; if you don't mind a derailleur and fancy a bit if off roading a rear hub may be better.

Don't know if Woosh are selling the torque sensor yet with rear hubs (check with them) but for my bike I got a front hub motor XF07 and my wife's bike is a Santana3 that Woosh built to order with a torque sensor and rear hub motor.

Thanks for taking the time to reply. The answers pretty much confirmed how I 'imagined' the location of the hub may feel alongside ease of fitting etc.

Gravel riding and bridleways are what I try to ride on to get away from the cars so I guess the rear hub is for me. Woosh are offering this on their website currently but would need to double check.

I don't expect to need as many chainrings as I currently have (3, 26-36-48) but I only have a 7 speed cassette and think that a 1x7 drivetrain would be a bit limited, even with assist! Bit of a pain as I've just upgraded my 7spd shifters and cassette so to go 1x10 or similar would send that money down the pan.

My other option is the XF08C standard kit but as a newbie I really can't decide if I would miss the Torque Sensor having never had it!

Cheers for the info

 

[Nosweat]

If you wonder if you would prefer a cadence sensor to a torque sensor then you probably need a torque sensor. Much more natural feeling - "like having bionic limbs" is how they are often described - whereas a cadence sensor effectively sets you a minimum speed depending on the power setting so limited control especially off road. If you can afford it I'd say go for a torque sensor.

 

[vfr400]

If you wonder if you would prefer a cadence sensor to a torque sensor then you probably need a torque sensor. Much more natural feeling - "like having bionic limbs" is how they are often described - whereas a cadence sensor effectively sets you a minimum speed depending on the power setting so limited control especially off road. If you can afford it I'd say go for a torque sensor.

That's not quite right. A lot of cadence systems use current control, which IMHO is the best system for a bike that you ride on the road and trails.

 

[Nealh]

If one wants a natural feel riding feel then forget ebikes and buy a push bike (unpowered), how any of you protagonist's can keep saying more like a natural feel is beyond me when you have 500/600w of power at your feet. I rode my brothers TS bosch bike and all the crap I keep reading about natural feel riding is so far from the truth. I found it to be as easy as my hub bikes with current control and actually on inclines would say more a kin to a moped in power though I did have to push harder on the pedals.

 

[Woosh]

torque control may be not useful on steep hills but would you agree that using your feet to control the power on flat roads and small gradients (where you use less than 250W power) feels more natural than selecting the assist level alone?

 

[sjpt]

Feeling 'natural' isn't that important. Any decent system should feel natural after an hour or two'. I feel very natural ghost pedalling.
As Nealh says:

If one wants a natural feel riding feel then forget ebikes and buy a push bike (unpowered), how any of you protagonist's can keep saying more like a natural feel is beyond me when you have 500600w of power at your feet.

though I must admit neither of our ebikes gives half a megawatt of power.

 

[vfr400]

torque control may be not useful on steep hills but would you agree that using your feet to control the power on flat roads and small gradients (where you use less than 250W power) feels more natural than selecting the assist level alone?

The reason you buy an electric bike is because you want assistance. I think what's more important than a natural feel is to be able to pedal as hard or easy as you want whenever you want.

Every system has advantages and disadvantages.

I still don't understand why you don't introduce current control on your bikes.

 

[Woosh]

I still don't understand why you don't introduce current control on your bikes.

I have had KT controllers and they are less satisfactory compared to the slightly more expensive Lishui controllers.
Also, I would make life hell for Andy if customers can change the values of the internal registers then tell him that their motor is sick.
Just look at how many times people ask you and NealH how to correct their P registers.
There is enough flexibility with Lishui controllers. When used with the KD58C LCD (like on the Q70 kit for the Brompton) you can choose 3, 5 or 9 assist levels and set the power ratio for each assist level.