Bosch gen 5 cx in a gen 2 trek rail 7

[Superfarmer]

Is it possible to upgrade the motor to the latest Bosch motor on my Trek rail 7 gen 2.

 

[Greg Watts]

Is it possible to upgrade the motor to the latest Bosch motor on my Trek rail 7 gen 2.

No - the Gen 4 CX drive unit and the Gen 5 CX are physically different motors with different mounting interfaces, so it's not a bolt-in swap on your Rail 7.

The Gen 5 CX moved to a new mount pattern and cabling setup that Trek's Gen 2 Rail frame simply wasn't designed around. Trek builds the motor mounting, wiring loom and battery interface into the frame casting for the specific generation it launched with, so retrofitting a newer drive unit means fighting frame geometry and connectors it was never made for - not a job any dealer will take on, and not one I'd want you attempting in a shed either.

Worth saying: this is separate from your Purion speed-reading issue on the other thread, which is a calibration/firmware matter, not a hardware limitation. If the motor itself is running fine otherwise, that's still the better use of your time than chasing a Gen 5 transplant.

If you're after Gen 5's extra grunt and the EMTB+ mode refinements, that currently means a new frame built around it - the Trek Rail+ runs the Bosch Performance Line CX Gen 5 (120Nm/750W) from £4,250, so it'd be a bike change rather than a motor swap on the Gen 2.