pas / Hollowtech

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simonineaston
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pas / Hollowtech

Post by simonineaston »

Has anyone experience of the combination of a pedal sensor fitted to a Hollowtech crank set? Any comments?
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
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simonineaston
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Re: pas / Hollowtech

Post by simonineaston »

Just to let others know, it turns out that the magnet ring, or moving part, of the pas is available in different forms, some of which are suitable for use with Shimano’s popular Hollowtech cranks. see eBay etc
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
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simonineaston
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Re: pas / Hollowtech

Post by simonineaston »

Chapter three.
The plastic pas, ‘specially designed to use with the Hollowtech bottom bracket, complete with the usual 10 magnets, has turned up and indeed has a centre hole large enough to clear the bulk of the external bearing, but the clips moulded into the ring to fit the inner sprocket of Shimano’s Hollowtech road cranks are of no use to me on my Hollowtech Alfine cranskset.
I’m intending to mount the sensor on five stand-offs, each glued to the inside of the crank web - see photo and diagram. Each of the five stand-offs will have its own magnet used to keep the pas in position. Does that sound appropriate to you, dear reader? Can you think of a better way?
Concave crank web
Concave crank web
Poor diagram of crank and sensor
Poor diagram of crank and sensor
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
rjb
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Re: pas / Hollowtech

Post by rjb »

Can you use 5 small neodymium disc magnets on the chainring bolt heads to hold the sensor ring in situ with an old steel inner chainring. :wink:
Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway X2, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840, Giant Bowery, Apollo transition. :D
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simonineaston
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Re: pas / Hollowtech

Post by simonineaston »

That would be a cool way to do it, but the sensor dia is too small, I think… the 42t chain ring lies entirely without the circle of the pas.
Picture of sensor & crankweb
Picture of sensor & crankweb
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
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simonineaston
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Re: pas / Hollowtech

Post by simonineaston »

I’m cutting up some aluminium tube for the stand-offs on a little Proxxon table saw - I’d forgotten (or praps never knew) how quickly ally heats up :oops:
S
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simonineaston
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Re: pas / Hollowtech

Post by simonineaston »

Nearly there - just got to check the gap between the magnet ring (shown) and the pas itself.
picture of crank web
picture of crank web
S
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Manc33
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Re: pas / Hollowtech

Post by Manc33 »

I ended up using 4 x 2mm cable ties and attached it to the inner chainring, that had to be 24t (22t is too small). Luckily the inner chainring has holes, making it possible. I had to cut notches in the plastic on the magnet disc so the chainring can recess into it. I have done over 1,000 miles with it like this and it's been fine. :mrgreen:

Image

Image



Chain clearance is OK:

Image
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simonineaston
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Re: pas / Hollowtech

Post by simonineaston »

That looks a great way to keep the magnet ring in situ, Manc33 :)
S
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Galactic
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Re: pas / Hollowtech

Post by Galactic »

Manc33 wrote: 27 Aug 2024, 12:35pm I ended up using 4 x 2mm cable ties and attached it to the inner chainring, that had to be 24t (22t is too small). Luckily the inner chainring has holes, making it possible. I had to cut notches in the plastic on the magnet disc so the chainring can recess into it. I have done over 1,000 miles with it like this and it's been fine. :mrgreen:
simonineaston wrote: 20 Aug 2024, 8:30am I’m intending to mount the sensor on five stand-offs, each glued to the inside of the crank web - see photo and diagram. Each of the five stand-offs will have its own magnet used to keep the pas in position. Does that sound appropriate to you, dear reader? Can you think of a better way?
I'm just wondering how the cable binder and araldite solutions are working for you? Any feedback after a few months use?

(I'm struggling with how to connect the sensor to an Alfine 39 tooth cranks, really annoying)
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simonineaston
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Re: pas / Hollowtech

Post by simonineaston »

Galactic wrote: 1 Oct 2024, 12:29pm
I'm just wondering how the cable binder and araldite solutions are working for you?
The use of stand-offs to attach the pas magnet ring to the Alfine crank worked out really well. The ring is attached by magnetic attraction alone, however this appears to be perfectly adequate as there are few if any, other forces. As is probably obvious, It's tucked between crank and the bottom bracket in a way that’s very protected.
The work required to measure and prepare the 5 standoffs was within my capability and given the materials - ally tube - quite easy to achieve given that I had a number of key tools ie a Dremel and a dial caliper. The materials I used cost less than a tenner and came from eBay. It wasn't what I’d call an easy project, but for someone with plenty of time and prepared to take it step by step, it went without serious setbacks.
The measured gap between sensor & ring is 3mm which sits nicely in the spec. which is quoted as ‘1-4mm’.
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
Galactic
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Re: pas / Hollowtech

Post by Galactic »

simonineaston wrote: 1 Oct 2024, 12:47pm The ring is attached by magnetic attraction alone
Bit confused by this, I thought the tube was ally? Or are the magnets strong enough to exert enough attraction to keep the assembly in place?

Good to know that this is an option, certainly looks a lot tidier than cable binders, but I suspect I'll be using cable binders plus some kind of glue (2-component?), not having the tools to measure and cut the tubes at the right angle to fit the spider.
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simonineaston
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Re: pas / Hollowtech

Post by simonineaston »

I did make a brief reference to the magnets pressed into the 5 standoffs but it was easy to overlook. These 5 extra magnets hold the pas magnet ring in place nice & snug. Here's a sketch.
Sketch of design…
Sketch of design…
S
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Galactic
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Re: pas / Hollowtech

Post by Galactic »

simonineaston wrote: 2 Oct 2024, 7:26pm I did make a brief reference to the magnets pressed into the 5 standoffs but it was easy to overlook. These 5 extra magnets hold the pas magnet ring in place nice & snug. Here's a sketch.
Ah, that makes a lot more sense. Thanks for taking the time to reply.
Galactic
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Re: pas / Hollowtech

Post by Galactic »

So, I've got the magnets for the PAS sensor (PASensor?) attached to the Alfine cranks. I was inspired by this Ukrainian fellow: https://www.youtube.com/watch?v=ZVVEFk5EiKY . He cut up a plastic canister (presumably HDPE?) and screwed that to the inside of this cranks, then screwed on the magnet ring to the piece of plastic using self-tapping screws.

As he said in the video (use auto-translate subtitles if your Ukrainian isn't what it used to be): use what you find around the house. I couldn't find a suitable plastic canister that was big enough, but I did find some lovely stainless steel 5l olive oil canisters. I made a template and snipped out the thin steel. I didn't do a good job of it (old tin snips with serrated edge that I couldn't sharpen even though I filed away at them for an hour), but it all works and I shall cut out another holding plate after a thorough testing. The advantage of the steel compared to plastic is that the magnet ring doesn't need any further fastening.

The magnets are about 4mm from the sensor, but it seems to work well enough (plug the sensor into the battery, turn the cranks and check the wee red light flickers on and off whenever a magnet passes). If I feel I need to close the gap a little I can put washers on the chain ring screws. I could attach the plastic holder that comes with the magnet ring, that will give me another mm or two, but then the magnets aren't as secure and I'd need to glue the magnets to the holder and somehow attach the holder to the steel plate.
Black Alfine cranks with a thin metal plate (golden coloured) screwed to the inside (bottom bracket side). A black ring of magnets is attached to the metal plate. Next to the cranks is a template in the shape of the plate cut from cardboard.
Black Alfine cranks with a thin metal plate (golden coloured) screwed to the inside (bottom bracket side). A black ring of magnets is attached to the metal plate. Next to the cranks is a template in the shape of the plate cut from cardboard.
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