Rail (625Wh) Trek Rail Bosch speed sensor magnet conundrum on centrelock rear hub

[nickf]

After months of dithering I finally decided to try out a mullet set up on my 2022 Trek Rail. I found a DT Swiss rear wheel at a really good price, although it was only available with a centrelock hub. My current wheel and disc rotor are 6 bolt, and of course the Bosch speed magnet fits onto the disc rotor using two of these 6 bolts. But not a problem, methinks, I'll just buy a centrelock to 6 bolt adapter and all will be hunky dory. Simples!

But having fitted the Shimano centrelock to 6 bolt adapter to the wheel and fitted the disc rotor in place, it's immediately apparent that the outer ring of the adapter (that threads into the adapter body to hold the disc in place) is just wide enough to obscure all of the 6 bolt holes. This means that there is no way to bolt the magnet in place!

I am currently pondering my options as how I could best bodge a way to attach the magnet in a way that ensures the speed sensor works reliably but doesn't stick out from the disc rotor and foul either the speed sensor or the seat/chain stays as the wheel rotates. There is very little clearance! I also know that some people have experienced Bosch motor errors (eg 504) that seem to be due to magnet and/or speed sensor issues, and I'd rather avoid all that!

I know that Shimano sell an alternative centrelock adapter ring that includes a magnet for the Shimano motor equipped ebikes, but I don't know if there would be compatibility issues with the Trek sensor.

Shimano centrelock magnet

Has anyone used this Shimano centrelock magnet with the Trek Rail speed sensor, and if so any issues with it? Or alternatively, before I leap in, any good ideas how to appropriately mount the Bosch magnet with the centrelock adapter?

 

[Bear-uk]

After months of dithering I finally decided to try out a mullet set up on my 2022 Trek Rail. I found a DT Swiss rear wheel at a really good price, although it was only available with a centrelock hub. My current wheel and disc rotor are 6 bolt, and of course the Bosch speed magnet fits onto the disc rotor using two of these 6 bolts. But not a problem, methinks, I'll just buy a centrelock to 6 bolt adapter and all will be hunky dory. Simples!

But having fitted the Shimano centrelock to 6 bolt adapter to the wheel and fitted the disc rotor in place, it's immediately apparent that the outer ring of the adapter (that threads into the adapter body to hold the disc in place) is just wide enough to obscure all of the 6 bolt holes. This means that there is no way to bolt the magnet in place!

I am currently pondering my options as how I could best bodge a way to attach the magnet in a way that ensures the speed sensor works reliably but doesn't stick out from the disc rotor and foul either the speed sensor or the seat/chain stays as the wheel rotates. There is very little clearance! I also know that some people have experienced Bosch motor errors (eg 504) that seem to be due to magnet and/or speed sensor issues, and I'd rather avoid all that!

I know that Shimano sell an alternative centrelock adapter ring that includes a magnet for the Shimano motor equipped ebikes, but I don't know if there would be compatibility issues with the Bosch sensor.

Shimano centrelock magnet

Has anyone used this Shimano centrelock magnet with the Trek Rail speed sensor, and if so any issues with it? Or alternatively, before I leap in, any good ideas how to appropriately mount the Bosch magnet with the centrelock adapter?

The magnet won't matter as it will work on both motors.
I swapped a Shimano centrelock hub for a DT swiss one and the adapter swopped over ok. Which I assume is a Shimano part
I also fitted a 2.3 disc, but had to file a bit out for the magnet and drill a hole for a securing screw.
Been working fine for a couple of years on my Bosch Gen 4 bike.

 

[nickf]

The magnet won't matter as it will work on both motors.

Thanks for your reply and your photos.

But I should perhaps have stressed the fact that the Trek Rail has its own proprietary speed sensor and diametric magnet rather than the more common axial magnets whose magnetic field's orientation is different. As such an axial magnet might not work with this speed sensor. I can't say for sure, but it looks to me like the Shimano magnet is an axial type.

Hence my question.... has anyone used the Shimano centrelock magnet with a Trek Rail?

 

[Bear-uk]

Thanks for your reply.

But I should perhaps have stressed the fact that the Trek Rail appears to have its own proprietary speed sensor and diamant magnet. I believe the diamant nomenclature means that it is a diametric magnet rather than the more common axial magnets whose magnetic field's orientation is different. As such an axial magnet might not work with this speed sensor. I can't say for sure, but it looks to me like the Shimano magnet is an axial type.

Hence my question.... has anyone used the Shimano centrelock magnet with a Trek Rail?

Well I've just been reading words that are alien to me
I never knew that there were different speed. magnets.
Is your bike fitted with the smart motor or Gen 5? As that would possibly explain why the magnets are now different from the old system.

 

[nickf]

Well I've just been reading words that are alien to me
I never knew that there were different speed. magnets.
Is your bike fitted with the smart motor or Gen 5? As that would possibly explain why the magnets are now different from the old system.

It was news to me too until I researched into the Trek magnet!

No my motor is the old (non-smart) gen 4. But it is not a Bosch magnet. It is a specific Trek item.

 

[Bear-uk]

It was news to me too until I researched into the Trek magnet!

No my motor is the old (non-smart) gen 4. But it is not a Bosch magnet. It is a specific Trek item.

I see
But what I don't get is Trek making something different to everyone else and complicating a basic system that works
It's looking like a trip to the dealers, unless someone actually knows on the forum

 

[fasterjason]

I believe the diamant nomenclature means that it is a diametric magnet rather than the more common axial magnets whose magnetic field's orientation is different.

Diamant is a brand of city bikes owned by Trek. I have not heard of someone trying mx on a Rail, but be prepared for pedal strikes. Run the mino link high and get some 145mm cranks. Good luck and let us know how that works out.

 

[nickf]

I have not heard of someone trying mx on a Rail

Try looking here Rail (750Wh) - Mulleting the Rail