kiltedcelt
100 W
So, I've built this beast of a tandem trike based on all 26x4.0 wheels and currently the rear wheel is built with a 170mm fat bike hub and a 9 speed derailleur drivetrain. My BBSHD is up front at the captain's position and at the stoker's position I have an independent drive system (same one used on the e-assist DaVinci tandems - had them machine a separate unit for me). I don't know exactly what I did when I built the frame but for whatever reason I can't get the lowest gear on the cassette to effectively clear the sidewall of the rear tire without bending the chain outwards in what looks like "quickly destroyed" manner, especially with the BBSHD power output and two riders pumping human power into the equation as well. I've had internally geared hubs on cargo bikes in the past, and I even ran this BBSHD on a cargo bike with an early generation Shimano Alfine 8 speed hub. Anyway, to improve chain lines I'm seriously considering building up the rear wheel with a 135mm hub instead of the 170 and going with either an Alfine 8, or a NuVinci N171, or NuVinci N380.
It seems like any of these would likely be okay to use with the BBSHD but I'm also wondering since this is a tandem and the whole trike is a lot heavier than my cargo bike was, which IGH is likely to be the best option in terms of durability, and handling the BBSHD torque. A few key things - I prefer to the use the BBSHD as e-assist and rarely ever use the throttle, and if I do I'm almost always still pedaling and I'm only using the throttle to goose a little more assist out of the system momentarily for say getting quickly away from a stop in traffic, to when needing to pass several slower cyclists on a path or something in a quicker amount of time. Most of the rest of the time we'd prefer to use the assist at a very low setting so we're getting still getting our exercise. We're looking at the e-assist on the tandem as something for extending range and when the trike is in single-rider cargo hauling mode (rear seat is removable and there will be a cargo deck), then the motor would provide a little more assistance. In both use cases though, we're never riding throttle-only or otherwise "hot-rodding" the BBSHD.
Other factors would be WHERE we would intend to use the trike. Probably the greatest usage will be on streets and multi-user paths, but it should also be able to handle hills and some rough road riding (gravel/forest service roads), and some light off-road, but mostly gravel double-track type stuff and not necessarily bombing down gnarly singletrack downhills or anything. So, which hub do you think would be a good match for this trike? I'm kind of leaning towards Alfine 8, but only because I have a lot of experience with them on several bikes, but I don't know if it can handle the torque of tow riders AND whatever the BBSHD is putting out. It seems like the N171 hub is pretty strong for use with mid-drives and the BBSHD in particular. They are of course still available new, but from what I understand I bit more complicated to set up and I'm a little wary on buying a hub that's been out of production for a long time and for which there is no warranty support and dwindling spare parts available. I know I can always buy guts for Alfine 8 hubs to replace them and I even know there are tools to do more extensive rebuilds of those hubs. The N380 seems like a decent choice as well, but again - what is warranty like, especially since NuVinci specifically won't warranty usage on anything over 750w (BBSHD is 1000w, of course), again I wonder about replacement parts and such since NuVinci is now "Enviolo" and have changed their hubs in appearance. I have no idea whether the guts of the new Enviolo hubs are the same as the N380/N360 though. I do see there is an Enviolo specifically designed for cargo bikes or things like rickshaws/pedicabs though. Of course those are their latest models and more expensive than I'm looking to buy. Anyway, any suggestions for a suitable geared hub for this build, or should I just focus on figuring out how to improve my derailleur chainlines?