Fitting PAS to square BB on road bike

[lovelock]

Hi, trying to figure out how to fit PAS to my road bike project.

Here are both the sensors I have:

I've taken off my crank arm and test fitted the lower sensor from the picture:

I've then refitted the crank arm:

Something about this feels incorrect? Its pushed the crank arm out and there is less thread now being used on the bolt but it does stay in tight. Should the sensor be cable tied so it doesn't rotate?

Anything I've done wrong here?

 

[Deleted member 4366]

That looks a bit close. I'd grind a bit off the inside of the pedal arm. The cable should be tied for neatness. That's enough to resist the minimal torque.

 

[Woosh]

you need a bottom bracket with a longer axle, So take the bottom bracketout, the length of the axle is printed on the label, something like 68mm x 108mm. Get one that is 10mm longer.

 

[lovelock]

you need a bottom bracket with a longer axle, So take the bottom bracketout, the length of the axle is printed on the label, something like 68mm x 108mm. Get one that is 10mm longer.

The costs for this project are going up a bit

Is there anyway for me to use the other sensor? I’ve tried it but when doing the crank up right it also pushes the plastic against the bottom bracket mount so probably not...

 

[Woosh]

The costs for this project are going up a bit

Is there anyway for me to use the other sensor? I’ve tried it but when doing the crank up right it also pushes the plastic against the bottom bracket mount so probably not...

yes, you can but it's equally fussy. You have to remove the bottom bracket, install the right side sensor (the one with the brass ring) between the frame and the right BB cup. Then dremmel out the plastic fins on the magnet ring and attach the ring to the smallest chainring.
The alternative is a new BB costing about £10. Halfords have them for a couple of £ more.

 

[lovelock]

Thanks for the thoughts Whoosh, i've taken a few minutes this evening to play around with washers and bolt lengths and after revisiting the idea from d8veh I think I can work around this.

This is the arm without the sensor:

The only reason there is not much room is because of the tapered section. I'm going to take it to a friend with a grinding wheel tomorrow and get that flattened off. I can't see me being able to fit the smaller sensor so will have to use the 2 part one.

 

[Nealh]

The answer is simple and two options have been posted.
the neatest is to buy a bottom bracket with correct length/longer axle for the one piece sensor.
Grinding a few mm off the inside face of the crank arm is the other.