Can I mount Qiroll on nonstandard Bike Friday tandem? Other options?

[Charlie Pendejo]

I have an older Bike Friday Twosday tandem, which mostly works great for touring with my nine year old. Only major issue is climbing hills - given our power & the loaded bike's weight, really need a little boost.

Adding minimal weight is a high priority: carrying the bike folded up in its bag, or maneuvering it up & down stairs (e.g. to take a subway), it's already near the limit of what I can reasonably handle.

So a lightweight friction drive is very appealing, and the Qiroll looks like the best functionality - weight - price tradeoff I've seen so far.

But the bike's geometry isn't compatible with mounts they offer.

https://imgur.com/fg87YvL

There's a Strida mount which looks like what I'd need, except they say it fits a 23.5mm tube. The tandem's seat stay measures more like 26.5mm.

https://imgur.com/vi1jQ1O

Any ideas how to mount this thing? I'm willing to shell out a few bucks or do a little DIY, but I'm not mechanically gifted.

Alternately, what other product should I be looking at, that won't add much weight - or significant drag when not in use?

 

[Dewey]

Sorry can’t advise on your friction drive idea. Bike Fridays official e-conversions use either a front hub motor or a tsdz2 mid-drive. Maybe go for the less power-hungry 36v tsdz2 model then you could use a smaller lighter battery similar to the bottle batteries @PedalUma uses on his conversions. You might be able to fit the latter if your crankset is square taper? If not there are replacement tandem cranksets for square taper and Lekkie sell an axle extender. Good luck.

 

[Charlie Pendejo]

Thanks Dewey. I knew about BF's front hub solution, and your suggestions prompted some additional reading and learning.

Mid & hub drive seem like better choices for most use cases, but add more weight to an already heavy rig than I'd like.

Mid-drive is additionally complicated by the left-hand chain connecting my tandem's two sets of cranks, the most common arrangement. Replacing either of my wheels for hub drive would mean I lose either the drum brake in front, or the 3 speed hum in back (in lieu of a front chainring).

Think I'll probably go with the Qiroll and find a way to attach it securely. Current thought is to have them toss in their mount intended for the Strida, and assuming the clamp won't fit my larger diameter tubing, try replacing that with something like the Problem Solvers water bottle clamp, after drilling a couple bolt holes for attaching the platform which holds the motor.

Gboost also has an intriguing minimal-weight friction-drive product which works with 20" wheels, but at a considerably higher price.