PAS does not fit bottom bracket

Laissez · Nov 14, 2020

So I got a bit of a problem here.

Pas I got is D12L from this set: https://www.aliexpress.com/item/4000258829938.html

It seems that there is too little space behind my crank or that space is too large so I can't connect that pas disc. Any ideas how I could fit this thing?

Thanks for your help!

Some pictures of the problem:
https://imgur.com/a/Kvep0T0

docw009 · Nov 14, 2020

I had that same problem with the integrated sensor. I sanded the plastic down. Still too thick. When I tightend down the pedal arm, it got crushed and wouldn't turn.

Went with a different style, the separate disk as shown in your photos. Mounted it on the chain ring, after also cutting of a lot of the center so it would clear the BB. I've never used the ring brackets to hold the sensor.

AHicks · Nov 14, 2020

That smaller section of the crank arm would be missing if I needed a little more room.

Mclewis1 · Nov 14, 2020

As already mentioned the two most popular options are a) if you don't want to do any filing and such just buy the PAS sensor for the otherside which mounts to the inside of the crank arm spider ... or b) if you are ok with a little metal work file down the inside of the crank arm.

Another option if you are ok with some plastic work is to measure that slightly smaller diameter area on the inside of the crank arm and take a look at your PAS disk. You can often remove the plastic fingers with something like a Dremel tool to open up the diameter of the opening to match that stepped area on the crank arm ... just make sure you can still snap the two halves together. The new opening doesn't have to be perfect, the magnets are large enough so that a little eccentricity usually won't be a problem.

Then fit the disk with it's new larger opening over that stepped area and remember to keep the correct orientation of the disk. If you are lucky you may be able to do all this without removing the crank arm but this will all be easier to do if you remove the crank arm. You'll need to use some adhesive to keep the disk attached to the inside of the crank arm. You'll probably also need to move the PAS sensor outwards just a little bit more.

Mark

Laissez · Nov 15, 2020

Mclewis1 said:
As already mentioned the two most popular options are a) if you don't want to do any filing and such just buy the PAS sensor for the otherside which mounts to the inside of the crank arm spider ... or b) if you are ok with a little metal work file down the inside of the crank arm.

Another option if you are ok with some plastic work is to measure that slightly smaller diameter area on the inside of the crank arm and take a look at your PAS disk. You can often remove the plastic fingers with something like a Dremel tool to open up the diameter of the opening to match that stepped area on the crank arm ... just make sure you can still snap the two halves together. The new opening doesn't have to be perfect, the magnets are large enough so that a little eccentricity usually won't be a problem.

Then fit the disk with it's new larger opening over that stepped area and remember to keep the correct orientation of the disk. If you are lucky you may be able to do all this without removing the crank arm but this will all be easier to do if you remove the crank arm. You'll need to use some adhesive to keep the disk attached to the inside of the crank arm. You'll probably also need to move the PAS sensor outwards just a little bit more.

Mark

AHicks said:
That smaller section of the crank arm would be missing if I needed a little more room.

Maybe I'll try to file that crank arm a bit and the plastic of the pas so it fits better. Thanks for your tips.

Edit:
Managed to fit it just removing the crank arm and installing it and then re attach the crank arm!

Mclewis1 · Nov 15, 2020

That's great news. Since the center section of the PAS sensor is often just a bit thinner removing the crank arm and installing the sensor sometimes gives you that little bit of extra space needed (should have mentioned this earlier ... sorry).

Since you've removed and replaced the crank arm make sure to keep an eye on if for the first few rides. If it comes loose make sure you tighten it up right away (and check for any new interference with the PAS sensor). If you keep riding on it when it's loose there can be damage to the tapered area of the crank arm which means replacing the crank arm(s) and sometimes the bottom bracket too.

Laissez · Nov 15, 2020

Mclewis1 said:
That's great news. Since the center section of the PAS sensor is often just a bit thinner removing the crank arm and installing the sensor sometimes gives you that little bit of extra space needed (should have mentioned this earlier ... sorry).

Since you've removed and replaced the crank arm make sure to keep an eye on if for the first few rides. If it comes loose make sure you tighten it up right away (and check for any new interference with the PAS sensor). If you keep riding on it when it's loose there can be damage to the tapered area of the crank arm which means replacing the crank arm(s) and sometimes the bottom bracket too.

Thank you! Tightening it is quite straight forward thing to do I need just 8mm hex wrench for it. I can keep it with me for couple rides for just to be sure.

PAS does not fit bottom bracket

Laissez

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docw009

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AHicks

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Mclewis1

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Laissez

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Mclewis1

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Laissez

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