Improving a Carrera Subway E (2021)

[teapots]

Hi, I did post with a lot of detail and photos of the components last night but for some reason it either didn't 'send' correctly or was deleted as I couldn't see my post this morning. But no worries, here goes again although perhaps not so long winded;

I recently purchased my first electric bike - a secondhand Carrera Subway E of 2021 manufacture, which had a mere 41 miles on it so was pretty much like new. However I do have one issue and one minor frustration;

1. On hot days (like today!) there is no assistance. Similarly if I leave it in the sun on cooler days. I understand from reading other posts that this is a common problem, and is most likely caused by the temperature threshold for overheat protection being set too low in the manufacturers software.

2. Like all 'road legal' ebikes, the assistance stops at 25kph, which I find frustrating as I ride a normal kike faster than this on the level, but obviousy I can't go so fast unassisted on this bike due to the extra weight and rolling resistance.

Having been reading, this model has a Suntour geared hub motor and controller, with the controller being pretty much 'un-tuneable'. There are a couple of threads on these forums where people have had success derestricting them by replacing the controller with a KT type and suitable screen e.g. the KT LCD3.

Would this be the correct controller? I believe from the posts I have read that the Suntour HESC motor is of the 'sine wave drive' type.

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Or this?

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I'm aware that the Suntour crank torque and speed sensors will not be compatible with these controllers, but I'm not bothered about that - I'm happy to just use a throttle on it instead. As for wiring I'm happy soldering and sleeving, but if there is a wiring harness available with the correct connectors that will save me butchering the stock loom.

Also are there any brake sensors that will work with the hydraulic disc brakes fitted to this bike? The ones I see on ebay all seem to be for cable brakes.

Thanks in advance for any suggestions.

 

[StuartsProjects]

Also are there any brake sensors that will work with the hydraulic disc brakes fitted to this bike? The ones I see on ebay all seem to be for cable brakes.

This type, first in the list in an ebay search;




Fit the sensor to the brake lever housing and the small magnet to the brake lever. You may need a different polarity of connector, depending on the controller.

 

[Nealh]

Bafang mid drive brake sensors aren't compatible with KT or other controllers, the pin out sequence at the higo connector are not the same as Julet connections used on non Bafang controllers.

 

[StuartsProjects]

Bafang mid drive brake sensors aren't compatible with KT or other controllers, the pin out sequence at the higo connector are not the same as Julet connections used on non Bafang controllers.

Fair point, however that style of brake sensor, with the male connector, is available for a KT controller, its what I have on my eBike.

 

[teapots]

Thanks for the reply's regarding the brake sensors. That's one problem solved at least!

Any thoughts on the controllers? Which one would be compatible with my bike?

cheers!

 

[StuartsProjects]

I used a magnet with a hole. Positioned it to work when the lever was pulled using a bit of double sided sticky tape. When the position was correct, I drilled a tiny hole in the lever and secured the magnet with a small contersunk self tapper.

I later added a zip tie around the brake cylinder body and brake sensor to reduce the risk of it being knocked off.

 

[Nealh]

A couple of memebrs have successfully used KT controllers with the HESC hub, one might want to opt for 22a 9 mosfet KT controller. As for brake sensors they aren't needed with KT contorollers unless of course one is using a throttle, in which case one sensor should be used.

The hesc hu wiring colour wise matches the std sequence used on most hubs and the KT's worked without issues. One will need to use the existing motor cable connector and join the wires to the new controller connections. Other wise one will need a new PAS, lcd, trunk cable to work. If one has issues with the speed sensor an exterior sensor and spoke magnet cna be utilised later.