Pedal Assist Sensors

[crossbreak]

interesting thread... the strain gauge in combination with arduino pro micro and a bluetooth module is very intersting. The Arduino Micro has differential ADCs, so i guess the signals of the strain gauges could be measured quite accurate. Bluetooth module and arduino micro are so small they fit on the crank easily. Two 18650 batteries fit into the hollowtech2 shaft, they can power the Arduino directly without the need of an additional voltage converter.


Best thing
Someone does this already and shares his code http://keithhack.blogspot.de/2012_08_01_archive.html

 

[Myrtonos]

One thing I read, and found quite strange is that pedal assist sensors first appeared only on 1989, even though, to my knowledge, they only require very simple technology, and similary sensors had already been part of automotive power steering for quite some time.

 

[Bikengineer]

This is a problem without an economical solution.
I've done a few kits now that all come with PAS sensor and it inevitably requires a longer BB axle or a single chainwheel or both. A simple split ring version of the PAS would be good also or a cheap version of thun BB that works universally.
The other gripe with kits is that many MTB's suited for conversion come with with integrated brake lever & gear shifter. Tricky to mod these or new ebrake levers and there aren't that many shifters with clamp attached.

 

[d8veh]

The other gripe with kits is that many MTB's suited for conversion come with with integrated brake lever & gear shifter. Tricky to mod these or new ebrake levers and there aren't that many shifters with clamp attached.

Use cable brake sensors:
http://www.bmsbattery.com/accessory/459-hwbs-hidden-wire-brake-sensor.html


Or buy a $3 cycle computer from Ebay. Cut off the sensor and fox it to your crossbar. Attach the magnet to the cable. You now have a rear brake switch for $3.

I've never found a bike that I couldn't fit a PAS sensor to. In the worst case, cut out the middle of the magnet disc and epoxy it to the inner chain-ring.

 

[Bikengineer]

Thanks d8veh. The sensors shown in your link are a great solution and cheap.

 

[d8veh]

If you get some, note that they're directional, so yo have to install them at the caliper end of the cable. If the little LED stays on, they're the wrong way round.

 

[oded]

do you think the newer split sensor could be a solution, or still no room for them in newer MTB ?
http://www.greenbikekit.com/dual-hall-pedelec-sensor-12-magnets.html

 

[oded]

someone thought of a solution for modern bikes -
http://www.aliexpress.com/item/king-meter-split-disk-PAS-magnet-rings-PAS-sensor/1988810409.html

 

[d8veh]

I guess they all work; however, you can normally fit the standard PAS sensor on the left side if you buy a $1 retaining ring to hold it on the BB thread. In the worst case, you can grind/file off a few mm from the inside face of the cranc arm ro make more room. The magnet disc has to be fitted upside down with the arrow pointing the opposite way to pedal rotation.

http://www.ebay.co.uk/itm/REPLACEMENT-24-TPI-BOTTOM-BRACKET-LOCK-RING-IN-SILVER-/271206943287?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item3f25318a37

 

[friendly1uk]

Are the red and the black bodied sensors the same?

I have a red one came with the 09 bottle battery controller. It is paired with a 6 magnet ring(or maybe an 8). The 12 magnet rings came with black sensors. Typically, I fitted the 12 magnet ring, then the red pickup. I have done no testing as yet, and don't want to take the crank off again. Not having span the 12 disc in my drill, holding a file to it to shrink it down till it fitted within the small ring mounting lobes. Then took 1mm off it's ~6mm width so fits on the minimal amount of exposed shaft. A mm that meant the sensor bracket needed a tweak to get some clearance.

I think it will be ok... The lcd3 used in these kits asks how many magnets. The red and black are not likely to latch in any way. There use of different colours is puzzling though, and they do have different part numbers on the yellow sticker.



If people are desperate enough to put a magnet on the crank arm and pickup on the frame, they should consider using a wheel sensor. It goes round in circles when you pedal to, and you can put as many magnets on as you like. Perhaps mount the magnet ring where a rear disc goes. I just put a magnet there myself, for a speed sensor.

 

[mfj197]

If people are desperate enough to put a magnet on the crank arm and pickup on the frame, they should consider using a wheel sensor. It goes round in circles when you pedal to, and you can put as many magnets on as you like. Perhaps mount the magnet ring where a rear disc goes. I just put a magnet there myself, for a speed sensor.

Nice idea, but the problem with that solution is that it would still be sending signals when you are freewheeling. Therefore the motor wouldn't cut out when you stop pedalling.

Michael