Craig’s e-gravel bike

Craig’s e-gravel bike

My friend Craig hasn’t been riding much for quite some time, and wanted a bike he could ride with others without getting dropped, and have confidence to go exploring without fear of how to get home! A gravel bike with electric assist was the solution for him. We looked at various motor systems before settling on the Bosch Gen 4 Speed motor with the largest capacity battery. This gives power assist up to 28mph, and a range of potentially up to 100 miles (depending on terrain and assist mode). Rather than just strapping the external battery onto a regular frame, I decided to have a go at integrating the tube-style battery into a truss downtube. This was a challenging build – one of the truss arms needed to be removable for installing the battery, I had to figure out and fabricate a custom bracket for the charging port, and all the little extras such as allowing for the power switch on the battery, a braze on for the speed sensor, and routing all the wiring internally.

Bosch don’t offer a ready-made solution for mounting the control switch on a dropbar, so I machined a bracket that paired with the front light mount to tuck the control module under the handlebar. The lights are integrated and run from the main battery – the Brooks saddle was carefully modified to allow a direct mount of the rear light, with all the wiring internal.

The bike has 45mm tires with plenty of clearance and mounts to add fenders. The paint is by Colorworks, with a nice little nod to the electric assist in the logo! At 40lbs it is not light, but that really doesn’t matter with the power of the motor – Craig took great pleasure in dropping me on my favorite hill!

One Comment

  1. i wonder how Alex Moulton would design an electric bike

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