Fitting PAS sensor to Claris Double - help please

[FoolThrottle]

Hi all,

I have recently taken ownership of a rear hub system and cannot wait to get started. The system doesn't have the PAS ring / sensor so I need to buy one and have been working out the best way to do this.
My bike has a Claris 50/34T chainring and I was all set to buy this: https://www.aliexpress.com/item/33064463265.html?spm=a2g0o.productlist.0.0.347177d2B2ynDb&algo_pvid=aed75eb5-d820-4172-aed6-6bad383405b1&algo_expid=aed75eb5-d820-4172-aed6-6bad383405b1-2&btsid=943257d9-0e37-4796-a858-86ac0457a52d&ws_ab_test=searchweb0_0,searchweb201602_10,searchweb201603_52

However I noticed that the sensors that attach straight to the Octalink / Hollowtech are for triple cranks, not double compact like mine

Ideally I would like a proper solution instead of trying to cut something up and failing but I am all ears to any suggestions going.

I could always change the bike or parts if this is sensible. My main aim is to keep it reliable so that I don't have to fiddle around or have failures whilst out.

Thank you pedelecers

 

[vfr400]

You need to a show a photo of your crank arrangement from underneath the bottom bracket so that we can see the spacing.

 

[anotherkiwi]

I think your 34 tooth may be bolted directly to the alloy crank arms am I correct? That won't work with the PAS you show. You need something to cable tie the disk to if you want it behind the chainrings, in fact it will stick to the 26 tooth with the magnets the cable ties are just to stop it from slipping out of line.

 

[Nealh]

I assume you have double checked that your kit controller has an outlet for a pas sensor ?
On one of my triples I removed the Granny ring to fit the magnet disc, obviously there is somewhere it was able to fix too.

The actual sensor is not the issue as that will fit behind the hollowtech BB shell as mine does or any other will do, the only issue you will have is placing/fixing of the magnet disc to the inside of the chain ring. You may have to resort to using epoxy to glue on or try some cable ties to secure the disc.
You may have to first fit a thinner larger diameter disc and then the magnet disc affixed on to it.

 

[FoolThrottle]

Thanks all.

I am currently away with work and haven't been home for the photos.
However, after further reading, I was wondering if I can simply replace the bottom bracket and put it on the left hand side.
The current BB is BB-UN26 and according to the specs is 113 spindle length. I probably need another 3mm (more if I lose space when the metal pas holder is put in too?).
Does anybody know the best size to move up to please? (Ideally I wanted longer on the LHS without affecting the RHS too much as it will move the chain line).
I looked at the potential versions and thought it would be best to check that this will work. ( I also read that I could UN55 or similar too).

SHIMANO Cartridge Bottom Bracket | SHIMANO BIKE-EU

The SHIMANO UN26 bottom bracket offers smooth rotation for square taper cranks.

bike.shimano.com

Thank you.

 

[Nealh]

Any wider axled BB will equally give more clearance on both sides of the bike, though some have taken a grinder to the BB axle. The metal PAS bracket is approx. 1.5mm in thickness, before you start guessing at what is needed you do need to check what clearance there is currently about 8mm between inside of crank and BB outer face is required.
The next sizes up from 113mm are 115,118 &122.5mm. Each one up in size will give half of the extra clearance on each side , so 115 will give an extra 1mm each side & 118 and extra 2.5mm each side and so forth.

 

[FoolThrottle]

Any wider axled BB will equally give more clearance on both sides of the bike, though some have taken a grinder to the BB axle. The metal PAS bracket is approx. 1.5mm in thickness, before you start guessing at what is needed you do need to check what clearance there is currently about 8mm between inside of crank and BB outer face is required.
The next sizes up from 113mm are 115,118 &122.5mm. Each one up in size will give half of the extra clearance on each side , so 115 will give an extra 1mm each side & 118 and extra 2.5mm each side and so forth.

Thank you.
I have asked somebody to take a pic for me

Sorry for the baby questions but I am assuming 118 will be too small (just 2.5mm, with 1.5mm taken up by the sensor holder). It is a shame that it knocks out both sides equally but I guess Shimano have bigger concerns than PAS.

 

[Nealh]

The wider the BB the greater the increase in crank Q value, wait until you are able to and post some pics of the chain ring spacing as fitted on this side is abit more stealthier.
Ideally for the LHS you need to mess around a little and fit the sensor, clamping it behind the BB retainer first then see how the magnet disc fits on the Axle. You need only 0.5mm/1mm of magnet clearance to the sensor, then you can decide on the actual BB length you will require.

 

[jarob10]

Looking at your photo, you have the option of creating pas wheel clearance by grinding some metal off the inside of the crank arm

Thank you.
I have asked somebody to take a pic for me

Sorry for the baby questions but I am assuming 118 will be too small (just 2.5mm, with 1.5mm taken up by the sensor holder). It is a shame that it knocks out both sides equally but I guess Shimano have bigger concerns than PAS.

View attachment 32131

 

[Nealh]

Looking at your photo, you have the option of creating pas wheel clearance by grinding some metal off the inside of the crank arm

Yes theoretically you could remove some of the taper off the inside of the crank arm but personally myself I'm loathe to doing such things.

 

[FoolThrottle]

Yes theoretically you could remove some of the taper off the inside of the crank arm but personally myself I'm loathe to doing such things.

Presumably you could just replace them with leaner crank arms? (Though I wouldn't have a clue how to determine which would work).

 

[vfr400]

Why didn't you take the photo from under the BB, like I asked? That photo doesn't show the chainwheel side, which is where you normally fit the PAS. Also, it seems to show a normal square taper BB, not an Octalink or Hollowtech.

 

[FoolThrottle]

Update..
Whilst I was away I ordered some sensors.
I have received both a red one that usually goes between the bottom bracket and frame on a thin metal circular mount and also a KT-D12L.

I wanted to use the KTD12L as I could stick it to the frame but for some reason it isn't working.
When I plug it in the red led doesn't come on, and it doesn't flash in any 4 orientations of magnet disc spinning.
However if I plug it into the throttle connector (same yellow julet) then the light is off but it does flash when the magnet spins (though it doesn't move the motor).
The red standard pas sensor does work which limits the issue area (though I don't want to use that).
Do I need to adjust a setting on my KT3 display or is the wiring wrong?
If the wiring is wrong how do I fix it without losing waterproofing etc?
Thanks to anybody who can advise this.



Ps vfr I didn't take a photo because it wasn't me at home taking it sorry.

 

[Nealh]

The sensor wiring doesn't always match the controller wiring so you need to have the correct sequence for them to have any chance of working, gnd to gnd , 5v to 5v and signal to signal.
Plugging PAS in to throttle connection won't work as it expects to see a different type of signal.
If unsure of sequence tell us the three colour on both side of the PAS connection.

 

[FoolThrottle]

The sensor wiring doesn't always match the controller wiring so you need to have the correct sequence for them to have any chance of working, gnd to gnd , 5v to 5v and signal to signal.
Plugging PAS in to throttle connection won't work as it expects to see a different type of signal.
If unsure of sequence tell us the three colour on both side of the PAS connection.

How do I do that? Won't this involve damaging both ends?

It is like this.. https://m.aliexpress.com/item/4000112370687.html

 

[anotherkiwi]

I bet that one is wired for a Bafang controller. Just going by the plug, usually the ones for KT controllers have JST plugs.

 

[Nealh]

How do I do that? Won't this involve damaging both ends?

It is like this.. https://m.aliexpress.com/item/4000112370687.html

Show us a pic of the controller & PAS connector.

 

[vfr400]

You have to cut one of the cables, then solder the three wires in the correct sequence. You can tell which is which by the colours. You need to tell us the colors to say which is which. On the controller side, you measure with a meter which pin is the 5v. You can confirm which pin is ground by measuring resistance to any black one, then you know the last pin is the signal wire. Alternatively, you can just twist each of the three wires together until you find which of the six combinations works. No harm will be done if you connect it the wrong way. It just won't work.

 

[FoolThrottle]

You have to cut one of the cables, then solder the three wires in the correct sequence. You can tell which is which by the colours. You need to tell us the colors to say which is which. On the controller side, you measure with a meter which pin is the 5v. You can confirm which pin is ground by measuring resistance to any black one, then you know the last pin is the signal wire. Alternatively, you can just twist each of the three wires together until you find which of the six combinations works. No harm will be done if you connect it the wrong way. It just won't work.

I have looked inside the pas sensor. Attached is a photo showing the new sensor (left) and original (right) provided by BMSBattery but which has never been tested.
It connects to a BMSBattery 08 case with built in sinewave controller (do I need to take that apart?).
The wires look pretty thin and I wonder if I can successfully cut the sensor cable in half and change the wire connections, especially given my poor handiwork.
Happy to proceed however best suggested.

 

[FoolThrottle]

Am I going to have to cut off the julet connector at the controller (battery) end to test the wiring (julet female connectors are too small to volt test. I'm trying to avoid modifying the expensive hard to replace parts