How to fit a PAS without disassembling the BB?

I have seen the BB of my Rockrider 8.1 says: "Do not disassemble"

http://i57.tinypic.com/ibj98w.jpg

Is there a way to add a PAS without having to disassemble the BB at all?

I have been searching the forum, and I see threads discussing this issue, saying it is very easy doing it with "sugru", and even there are some pictures about it. Probably I am too slow, but it is still not clear to me how it works.

Can I buy a standard PAS (such as the 12-pole PAS of BMSbattery) and add it easily, without disassembling my BB and without needing to have special tools / capabilities to do tailor made pieces?

Thanks.

That label means that you can't take the bearing out of its holder, not that you shouldn't disassemble the BB from the bike.

To fit a PAS to a 68mm BB with Hollowtech crankset. For 73mm leave out steps 4 and 5:

1. Drill out the magnet disc to 25mm. You can use a Dremmel because you don't have to be very accurate. Put a small chamfer on the edges of the hole so that they don't interfere with the bearing holder seal when clamped up..
   
2. Remove the cranks.
   
3. Remove the BB by unscrewing the two bearing holders
   
4. Throw away the spacers that sit behind the bearing holders
   
5. Remove the plastic sleeve from between the bearing holders and throw it away.
   
6. Unscrew the sensor from its bracket and fix it back on to the other side
   
7. Screw in the two bearing holders with the Sensor held behind the left side one.
   
8. Insert the chainwheel crank
   
9. Slide on the magnet disc and clamp it against the bearing holder with the left crank. the disk can go two ways up. It has to go in the opposite direction to the arrows on it.
   
10. If when you test it,it only works when you pedal backwards, you've got the magnet disc the wrong way round.
    

You don't need any special tools.

You can fit any standard pedal sensor. You don't need a 10 magnet one, but it'll work OK.

It should look something like this when done. It's very easy compared with a non-hollowtech type:

http://i451.photobucket.com/albums/qq236/d8veh/Misc%20bike%20stuff/hollowtechcrank_zpsda9f5cd5.jpg

or buy one of these (about $5):

http://b-t-n.en.alibaba.com/productgrouplist-220561404/PAS_sensor.html

http://i01.i.aliimg.com/photo/v2/384164997/BTN_ebike_pas_sensor.jpg_350x350.jpg

On a Hollowtech crank, you still have to remove everything because there's no space for the magnet disc until you remove the spacers from behind the bearing holders. Then you need to remove the internal spacer because the bearing holders will e closer together. So,unfortunately, there's no advantage of that type of PAS arrangement when you have a Hollowtech type BB.

The method I described above is very simple and only takes about 5 to 10 minutes to do once you've drilled and chamfered the magnet disc

or buy one of these (about $5):

 

http://b-t-n.en.alibaba.com/productgrouplist-220561404/PAS_sensor.html

 

http://i01.i.aliimg.com/photo/v2/384164997/BTN_ebike_pas_sensor.jpg_350x350.jpg

Very interesting product. Please correct me if I am wrong:

with this product, I do not need to disassemble anything, it just fits "on top of" my existing assembly, right? Or do I still need to do something additionally?

This webpage is an interesting one, because they also have a hydraulic brake e-switch. Probably it makes sense to buy the two products at the same time.

Edit: I guess, after looking at http://www.king-meter.com/upload/files/SSP-DH.pdf that one needs to take out the crank in order to fit this piece. But still is "less disassembling" that with traditional PAS?

Edited March 19, 201412 yr by Arbol

The method I described above is very simple and only takes about 5 to 10 minutes to do once you've drilled and chamfered the magnet disc

The part I fear is "(...) once you've drilled and chamfered the magnet disc". Ideally, I would prefer a solution where the words "drill" and "chamfer" are not necessary, both for my practical inabilities, and for the empirical fact that once one disassembles something which works, the probability that stops working, or stops working as well as before, are very high.

By the way, there is another product which is similar but not identical to the one quoted above:

http://b-t-n.en.alibaba.com/product/424433629-220561404/electric_bike_force_sensor_with_1_1_assistance.html

Which are the differences, if any?

The drilling is very simple if you have a 1" drill, If you don't, a Dremmel will rout it out, or you can use a round file to file it. It's not very difficult, but obviously, you need one of those tools. As I said above, you don't have to be accurate. Oval or irregular shape is OK. You just have to make the hole big enough to slide over the crank shaft. You can't really get it wrong.

Chamfering just means that you have to remove the sharp edge with a scraper or file to stop it cutting the seal, which it's pressed up against.