Pedal Assist

MINI revisited: It’s electric!

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While e-bikes can be a divisive topic among cyclists, it’s hard to ignore their increasing popularity. Admittedly it took me some time to warm up to the idea. Do I still get a workout? Is it “cheating”? After test riding an upright e-bike, I realized my worries were unfounded and it was time to transform the MINI once again. This time into an e-recumbent bike suitable for just about any terrain.

E-assist options

Azub offers attractive e-assist builds with Shimano Steps or Brose. The electric motors are integrated into custom booms, wires run internally, and the battery is mounted on the rack. Unfortunately, Azub can’t sell an e-assist upgrade (probably licensing-related?). Thankfully there are plenty of after-market options. While they won’t look as sleek, they’ll be a fraction of the cost if you don’t mind a little DIY work.

Some e-assist kits place the motors in the rear or front wheel hubs while others place them at the cranks (i.e. mid-drives). Two popular mid-drive manufacturers are Bafang and TongSheng. Both seem like good choices, and in the end, I decided to get the TongSheng TSDZ2 motor.

TSDZ2 specs and features

The TSDZ2 has a small form factor yet puts out an impressive 500W of power and 100Nm of torque. The 8 lb motor assists at up to 28MPH and/or 100RPM (you can always go faster but the motor won’t assist you). It can be installed on any bike that has a standard 68-73mm bottom bracket.

The most attractive feature of the TSDZ2 is the torque sensor which provides a more natural pedaling feel. With a torque sensor, if you pedal gently you get a gentle assist, and if you pedal hard the motor will assist more. In contrast, without a torque sensor, a motor will give a flat level of assist as long as you are pedaling. The torque sensor obviates the need for brake sensors to cut power since the motor is quick to respond when you stop pedaling.

While the motors are widely available, I purchased a recumbent-specific kit (the ECO+) offered by Eco-Cycles. They provide cable extensions to accommodate long recumbent frames, and a boom clamp specific to your boom diameter for securely mounting the motor. Eco also offers additional upgrades, including a software upgrade (OSF upgrade) that allows for custom assist levels and higher RPM assist.

The kit I chose included a more durable PEEK plastic gear inside the motor unit, the SW102 small LCD screen, and a 42T chainring to handle moderate hills. I skipped the throttle option in favor of always having to pedal. I also passed on the custom software upgrade to keep things simple.

Installation

My local bike shop installed the motor onto the boom for me, and I installed the rest myself. I used zip ties to run three cables along the bike. One cable ran up the steering assembly to the display screen. Another cable ran to the back chainstays for a speed sensor. The third cable ran to the battery. I mounted the battery (52v 13ah Jumbo Hailong Shark; 11 lbs; 30-60 mile range) beneath the seat with the versatile T-Cycle universal battery mount.

Azub owners take note of the braze-on for the derailleur cable on the boom. It’s situated exactly where the boom clamp for the motor wants to be.
Fortunately, my LBS improvised a small bracket to push the position of the clamp back a few cm to clear the braze-on.

Riding with e-assist

It’s no wonder e-bikes are so popular. With the pedal assist, I no longer have to worry about how hilly a particular route is before I go out. I still have to work to get up those hills, but I can get there faster.

I can choose from four assist levels (eco, standard, super, turbo). With the torque sensing system, at each assist level, the system will add a percentage of the power you are outputting. So if I’m putting out 100 watts while using the first assist level, the motor will add 40% (or 40 watts) to the output. That percentage keeps going up at each assist level, so you can decide how fast you want to go at the output you’re producing.

Another benefit I had not anticipated is being able to quickly clear intersections from a stop. Cars don’t have to wait for me to get up to speed, and I can spend less time worrying about them getting mad. Relatedly, I can also be more patient since slowing down or stopping for others isn’t such a big deal when I can get back up to speed easier.

It’s only been a few weeks of riding my electrified MINI, but I can safely recommend e-assist to anyone looking to enjoy more time on their bikes without fearing those hills.