Enviolo for a long-tail mid-drive cargo bike: advice on selection and required components

[Peddlin' Pedro]

As described elsewhere I'm in the process of converting a Kona Ute long-tail cargo bike to mid-drive. As part of that I've been debating whether to:

1. Refresh the existing 2x drivetrain with a wider range cassette to better deal with the reduced spread from the TDSZ2 42t up front, or
2. Go with a Enviolo/Nuvinci rear hub system

I'm aware of the increased system-drag of these hubs but that'll be overcome by the drive. I'm more interested in what a suitable spec would be for my use requirements, i.e. multiple daily runs at gross weight of 140-170kg with some decent (but not too long) hills and with a detuned 750w TDSZ2 assisting.

Do I need automatic or manual? Trekking or cargo? What other bits do I need to fit the system, such as disc brake adapters etc? What system cost would I realistically be looking at (excluding wheel-building costs)?

Thanks!

 

[vfr400]

I'd avoid a Nuvinci. I don't know what the latest ones are like, but the N360 slips with 22 amps and 36v. Also, they don't like shifting under the loads that a crank-motor makes, which breaks the weedy shift cables. And they're heavy.

If It were my bike, I'd be looking at a slow wind Bafang BPM or CST in the back at 48v. That will take all the load off your transmission and give you a much more pleasant ride. With a crank drive, you're going to be replacing chains, cassettes and derailleurs every other week.

BMSBattery have both 201 rpm Bafang CST and BPM. The BPM is stronger, but has freewheel gears, so 7 speed max. How many speeds do you have at the moment?

Bafang 48V500W CST Rear Driving Hub Motor RPM 201

48V Bafang CST 500W Rear Driving Hub Motor for EBike.

bmsbattery.com

Bafang BPM2 48V500W Rear Driving E-Bike Hub Motor RPM 201

Bafang BPM 48V500W Rear Driving EBike Hub Motor.

bmsbattery.com

That link says 36v, but when you open it, it says 48v.

 

[Peddlin' Pedro]

I'd avoid a Nuvinci. I don't know what the latest ones are like, but the N360 slips with 22 amps and 36v. Also, they don't like shifting under the loads that a crank-motor makes, which breaks the weedy shift cables. And they're heavy.

If It were my bike, I'd be looking at a slow wind Bafang BPM or CST in the back at 48v. That will take all the load off your transmission and give you a much more pleasant ride.

BMSBattery have both 201 rpm Bafang CST and BPM. The BPM is stronger, but has freewheel gears, so 7 speed max. How many speeds do you have at the moment?

Bafang 48V500W CST Rear Driving Hub Motor RPM 201

48V Bafang CST 500W Rear Driving Hub Motor for EBike.

bmsbattery.com

Bafang BPM2 48V500W Rear Driving E-Bike Hub Motor RPM 201

Bafang BPM 48V500W Rear Driving EBike Hub Motor.

bmsbattery.com

Thanks, that's really helpful input. Always useful to get people's real-world experiences, especially when things haven't gone to plan. Already got the TDSZ2 though I'm afraid (arrived today) and given the loads and use pattern I'm reasonably confident that's the right choice.

According to Enviolo's product info they vary quite a bit in their max torque ratings: from 50Nm for the 'City' version all the way up to 120Nm for the 'Sportive'. But that's about as much as I know about their systems in particular.

I do understand the technology quite well though as it's essentially a CVT style viscous coupling, albeit in planetary form. The potential issues are that exceeding the rated torque means exceeding the fluid's ability to resist shearing forces, and so they slip. As with any viscous coupling, if the fluid is contaminated or as it degrades over time then the system will slip more. Which is all fascinating theoretical stuff but doesn't change the fact I know naff all about fitting these systems to bikes