What kit for Bullitt Cargo Bike

[tchill]

Hiya, I have been thinking of electrifying our Bullitt Cargo Bike. I don't feel the need for a massive assistance as riding up hills is currently fine even with heavy shopping (me: 70kg, bike+box ~25kg, week's shopping 60kg -lots of tins etc ;-)). But we have another kid on the way and I need to make a bigger box, so the weight of two kids and a larger (non-aero) box on the front is an issue for my partner (50kg). I am familiar with a power meter on my road bike, so have a good feel for the power needed on this bike. I think it is probably ~ 200-300W to hit 15.5mph on flatish terrain. It currently has a Alfine 11 at back and 42t at front (good lowdown gearing, topping out at ~25 mph). Also the hydraulic brakes are a must on this bike. It has disc brakes and standard QR.

My criteria/wants.
- I love riding this bike - it is gueninely loads of fun in its current config - so want the opportunity to ride without assist freely-ish, when I like.
- I have no interest in throttle e-assist and don't really like cadence sensing (both of us like the exercise cycling provides). I.e. not the bafang BBSO1
- THe Tongseng TZDZ2 mid seems ideal, but would need cutting the frame (which I won't do ;-)
- The only scary thing about a cargo bike, is when unlaiden on slippery roads, the front wheel has little traction for breaking (or in this case) steering. This is fine whe nyou have full control, but I think a cadence front hub could be dangerous

Thoughts:
- Torque sensing bottom braket and a front hub? No brake/pedel sensor.

So, I ahve no experience with electric bikes (apart from cycling others) do you think this would allow the control needed for safe riding? Particulaly will it instantly reduce power to the front if you stop pedelling (i.e. no torque). Any suggestions on actual best kit? Reliable BB torque for standard shell (without the need to drill holes) and a good reliable front hub, without too much freewheeling resistance? I will build the wheel up myself, as the wieghts on the front can be large, so a good quality rim/spoke choice is needed.

Any thoughts/expertise v welcome.

 

[vfr400]

I have one thought, which you're not going to like. you should have spent more time doing it than researching it. It sounds like you've hyped yourself up into a state where you're scared to do anything. Either you want assistance or you don't. Fit a cheap hub-motor system, switch it on when you need assistance and switch it off when you don't. If it turns out that the wheel isn't strong enough, which I very much doubt, rebuild it with whatever you think it needs. The only important thing is that you get a motor that has a max rpm about 1.3 times the wheel's rpm at your modal speed.

Once you have your electric assist, you can decide if anything needs changing. None of the stuff is very expensive apart from the battery and it can all be mixed and matched. All motor kits can supply the power you want. I'd always fit a throttle. It's very useful sometimes, especially when you want a burst of speed to get through a traffic junction or round a roundabout rather than fiddle with buttons on the control panel.

 

[tchill]

@vfr400 thanks for the comments, wise words Will try the throttle too...