Posted by Jim Strasma on February 12, 2013
Late last fall, I added a BionX SL350 electric assist to my family's Terratrike Rover 8 Tandem. It was a great solution for us, except for one thing. Because the new BionX wheel replaced the original, we also lost use of the original 8 speed internal gear shift.
This area being a flat part of mostly-flat Illinois, that wasn't much of a problem. The BionX has been strong enough to power us up any slopes we've found thus far. However, it's been a close thing a couple of times, so I really wanted to add back the original ability to shift gears..
Because the Rover has a horizontal axle dropout, it first needed an adapter, to allow it to mount a rear derailleur. To the rescue comes Problem Solvers, whose CH0910 fits easily in a horizontal dropout, and acts as a derailleur hanger. The BionX wheel is designed to work with a freewheel, rather than a cluster, and ours already had an 8 speed freewheel, so all that was still needed was an 8 speed rear derailleur and a matching 8 speed twist shift for the front handlebar. (I'd already removed the one for the internal 8 speed hub, and Joe assured me that no, I could not just reuse that one.) Add in a tandem-length shift cable and housing, and presto - 8 speeds again!
What a lovely project for a snowy winter day! Note: I used a medium cage rear derailleur, to minimize chances of it hitting the ground when riding. I was a bit worried it wouldn't be able to handle the full range of gears, but no worries. With only one derailleur involved, even a medium cage is sufficient for most any standard freewheel.