Need for speed

Speed kills, but it also thrills.  The converse is also true:  Slow is safe, but oh-so-frustrating.  My manual wheelchair travels slowly because steering is problematic, shoulder power is limited, and obstacles abound.  Amazingly, the Firefly electric front wheel attachment solves these problems.  Power at the wheel is up to 350 Watts, similar to a professional bicyclist and over 10 times more than most people can get out of their shoulders.  The handlebar allows for proper steering, and the longer wheelbase improves handling on non-ideal surfaces, which are almost all of them in my city.  It brings out the joy of riding something fast, which must have been etched into our DNA long ago.

With speed and power comes danger!  Go too fast through a turn or cross a drop-off at an angle, and you gain a new appreciation for the tippiness of high center-of-gravity tricycles.  Someone more adventurous than me has maybe perfected the technique of balancing on two wheels to corner fast without the need for body English.  Hopefully they were wearing elbow pads.

Credit: Martin Pettitt originally posted to Flickr as Race Of Champions (CC BY 2.0)

But even straight-line speed is fun and helps eat the miles if you're going somewhere.  My first impression of the Firefly was that it's pretty darn slow.  Releasing the wheelchair's rear brake locks helped (duh), as did reading the instructions to understand that the device starts in 1st "gear", which has a low speed limit.  Setting the "gear" to 5 raises the top speed to 20 km/h (12 mph), already pretty fast if you're travelling on a sidewalk.  That's still an artificial restriction, which can be removed by adjusting the LCD controller.  Then the limit comes from the motor and battery voltage, and a fully charged battery reaches 24 km/h (14 mph).

There is a saying about all-wheel-drive cars, that they just get you to your accident faster.  Be that as it may, it would be nice to go faster than 24 km/h on smooth and clear pavement.  One option is the Phaserunner motor controller whose manual describes "Field Weakening for Speed Boost".  Apparently, the motor coils can be energized in a tricky way to gain 15-20 % in speed, at the expense of battery drain and maybe motor stress.

The Firefly's motor controller is a circuit board inside the battery base that is connected to the wiring harness.  All of those connections will make it hard to replace.  In the end, it might be more effective to replace everything (motorized wheel, the battery and maybe controller) with higher voltage parts that can go faster.  Update:  internet comments claim that most 36 V motors can operate with 48 V batteries.  I'm curious if anyone has done this already.  This could be a good project for the winter when I'm snowed in.  The cat's meow would be to also drive the rear wheels.