I believe the Stoke Monkey would deliver better performance on steep hills than a hub motor, because it drives the wheel through the chain and the bike’s gears. You can keep the revolutions high and the torque relatively low by shifting to a lower gear. The downside is that you have to remember to throttle back before you shift in order to avoid damaging your components or jamming the chain. The advantage of hub motors is that you don’t have to worry about that: the motor’s power is added after your muscles have put in their effort through the chain.

I will investigate moving the brake mount as you suggest. I suspect there is an obstacle, or my bike technician would have recommended that when we were stymied during my latest brake overhaul.

I agree that the BionX has the best features of all the systems I’ve seen but as you have experienced it is not fully able to deal with cargo bike duty. I am going to try to put together a system of my own. I will use the BionX functionality as a target but I will focus on better motor cooling. I am also going to see what I can do about the controls response time as all of the e-bike I have tested seem to have a very irritating lag.

I am wondering how your experience is an argument in favor of the Stoke Monkey? Couldn’t it overheat going up a steep hill?

Did you think about getting a brake mount put in between the seat stay and the chain stay? I saw a Bike Friday tandem in San Francisco w/ the caliper mounted there. If it works w/ your frame geometry this location is safer due to brake forces pushing the axle into the dropouts. There are a lot of standard 203mm rotors around that you can pick up on sale. No need to spend too much. They are a wear item that need to be changed about every third (or fourth) pad change.

As I think of it, I think this is a reasonable explanation for the cutout of the motor during my test drive of the Kona Electric Ute. I was riding up a pretty steep hill fairly quickly. It’s possible that the Ute’s smaller motor detected excessive heat and shut down. It recovered during my relatively level ride back to the bike shop.

The possibility of heat-related shutdown may apply to many hub motors that could be used on cargo bikes. It’s definitely a topic I intend to explore in a future article. (Yes, I know, one more argument in favor of the Stoke Monkey…)

Regarding the torque arm, BionX does sell one (part number 012038), and I intend to install one as soon as possible.

At this point, I can highly recommend the BionX motor for quietness, functionality, and reliability. However, I have a few complaints. The regen cutout issue is the most serious. Occasionally, after hard braking, the regen feature seems to get stuck on for maybe 5 seconds, producing an unpleasant stuttering as I start to pedal. This passes pretty quickly and does not have any lasting effect, but it caused me concern the first few times I experienced it. Finally, the LCD display which shows how much electricity is being used or generated does not seem to be calibrated for my loads. The graph disappears if I’m climbing a hill too steep, or when I apply regen braking faster than 15 m.p.h.

I’ve been able to live with these quirks because the motor, the regen braking, the integrated battery/controller, and the torque-proportional activation are so good. I haven’t seen any other motor that I like half as much. It’s a little expensive, but definitely worth the investment for me.

If I get a timely response on the regen issue, I will ask what BionX thinks about my shallow dropouts, and we’ll see if they have any suggestions.

The 203 or bigger rotor is a very good idea. If you have a good framebuilder in your area (or if you area near the original builder) you should be able to get some disc mounts inside of the rear triangle. They should fit there.

Any luck with the torque arm investigation?

I agree that personal responsibility and appropriate caution are the best safety measures we can have, and the price is right! For seasoned cyclists and cargo bikers, this probably isn’t a big concern. But as people start looking for transportation alternatives and cargo bikes with motors become more prevalent, I worry about casualties. I worry about someone like myself just a few months ago, who might have read that a certain cargo bike could haul 400 pounds in addition to the rider. With a motor to accelerate that load to 20 mph or more, the standard brakes will not be adequate to stop that bike in a reasonable distance, even on level ground.

In this case, the combination of powerful motor and barely adequate brakes could be deadly. Is this the reason that manufacturers seem so reluctant to push electric cargo bikes? It’s hard for me to say it, but it feels like a lawsuit waiting to happen. I would love to hear that my fears are exaggerated.

If bike safety was regulated like car safety we might be a bit safer, but certainly more restricted. I doubt we can rely on manufacturers to build us totally safe bikes at this point and so personal responsibility and riding within the limits of the bikes are important strategies.

In terms of a totally integrated ready to ride product I don’t think a one person electric bike like this exists as yet so certainly not for a cargo bike. Sadly I recently talked a friend out of purchasing an electric bike for his mother as I just feel the reliability and after sales service is not there yet.

Regarding your specific problems,I suppose the rear rotor is not cooling well tucked in next to the hot motor and behind panniers. I wonder if you might get a 185cm disc to fit better? A standard Avid BB7 rotor would not cost much to trial anyhow. Regarding the shallow dropouts, you might see if Bionix have a “torque arm” option instead of that slotted washer, or you might source one from someone else. I think the axle on you motor is fairly standard and could fit any torque arm. Check the electric bike forums here and you may find a local supplier http://endless-sphere.com/forums/.

Enjoying your blog keep it up!