Hardware Traction: What We Built in 2021

Over the past 12 months, Bimotal has made considerable additions to the list of high quality products and tools developed in-house at our workshop in San Francisco.

Late in 2020 we finished work on an integrated electrical connector for the Elevate drive unit. This made a big difference, removing a mess of wires and enabling a quick and easy mount and dismount from the bike. These functional gains resulted in a cleaner, more elegant, form factor.

We re-designed the two gears comprising the motor–brake rotor interface. By design, these gears run without lubrication. Rigorous testing throughout the second half of the year has produced promising results, and reliability testing is on-going in our effort to build a durable system.

We love the simplicity of this design, but stay tuned for some cool thermal fins on our next iteration.

A key component in this effort is our proprietary benchtop test rig. This was up and running in the first half of the year, and by August we’d developed our own data logging system and download tool for use either in the workshop or out in the field.

This data logging system is critically important for product analysis, enhancing our ability to engineer solutions and make parts with greater resilience to a wide range of observed conditions in real-world use. We can focus on the specific areas of a component that need improvement through insight to several metrics, such as thermal management and torque delivery.

Going forward, our data logging system will continue to provide invaluable information across a range of applications related to Elevate, and we will develop the platform for additional uses.

All this great hardware needs battery power. Early in Elevate’s development we found nothing on the market that contained a 52V battery in the space of a bicycle water bottle, so we decided to make our own. 

A Battery Management System (BMS) monitors and protects the battery, keeping it in a safe operating condition. We designed our BMS from the ground up, and our own firmware to run it. We’re pleased to say it is proving reliable and we’re on the cusp of bringing a capable, neatly packaged, 52V bottle battery to market. 

Designing and simulating a motor from scratch involves a significant number of variables and unknowns. We were excited that our original motor simulations predicted steady state torque within five to 10 percent of real world performance, which is actually very impressive for a simulated model with as many variables as a full drive unit with motor and gearbox. 

We are encouraged by its performance, which continues to improve. Burst torque is excellent, and we are currently making adjustments to extend the duration of high-torque output. 

What’s next?

The principles of our work on Elevate apply to key metrics and qualities across the micro-mobility world, namely: weight, power and versatility. Keeping Bimotal’s engineers focused on these metrics is leading to opportunities we scarcely imagined a year ago. With our initial work on the Elevate system nearing completion, we are starting work to bring our powertrain into the wider micro-mobility space.

We are pushing at the boundaries of what can be achieved with current battery and materials technology. Bimotal’s engineering team is demonstrating the skill, experience and imagination to continue its progress to new heights in the areas of reduced mass, greater efficiency and increased versatility, for both our own products and those of our clients.