Spare magnet

[M. Tartiflette]

Does anybody know if this will work to take as a back up for a Bosch magnet?

https://www.amazon.co.uk/gp/product/B000OYFENU/ref=ox_sc_act_title_2?smid=A3P5ROKL5A1OLE&psc=1

 

[vfr400]

You only need a magnet that can provide enough magnetic field when it goes past the sensor, considering the strength of the magnet and how close it is to the sensor. If it's lacking in either of those parameters,you can make it stronger and closer by adding neodymium disc magnets like these.
https://www.ebay.co.uk/itm/CrazyGadget-Neodymium-Super-Strong-Magnet-Round-Disc-N50-Grade-10mm-x-1mm/352238193596?epid=696084373&hash=item5203084bbc:m:mz-srKBSlQk5DTku_LNNWxQ

 

[Andy-Mat]

Does anybody know if this will work to take as a back up for a Bosch magnet?

https://www.amazon.co.uk/gp/product/B000OYFENU/ref=ox_sc_act_title_2?smid=A3P5ROKL5A1OLE&psc=1

This is a apparently a "spoke magnet" that certain types of bike computers need to calculate speed and distance covered.
I do not know if they need to be a north or a south pole facing the frame sensor, sadly, it never ever crossed my mind to check.
But with a small third magnet, it would be easy to check the polarity of the original Bosch part and the possible replacement, as it will either repel or attract. Naturally check using the same side of the third magnet!
But its quite possible that it doesn't matter about the polarity either way....easy to find out, just try it!!
Furthermore, if it does matter, its probably easy to pop the magnet out (mark first!) and glue it back on the clamp, reversed!
Its cheap enough to buy and see if it does the job you need it for!!!
I always loctited the screws when I had one (present e-bike uses the Hall effect sensors apparently), and never lost one!
regards
Andy

 

[M. Tartiflette]

Thanks for the feedback, both. Will try out that magnet and see if it works.

 

[danielrlee]

But with a small third magnet, it would be easy to check the polarity of the original Bosch part and the possible replacement, as it will either repel or attract. Naturally check using the same side of the third magnet!

No need for a third magnet. If the two magnets are oriented in the same polar direction, their active faces will repel each other.