Originally Posted by
mconlonx
DualDrive conversion update:
Alright, I ended up with a "floating" stop at the top of the chainstay/swingarm, and drilled a hole in the bottom where the cable comes through to the hub quick disconnect. Very much like an original spec Birdy with DD, except a lot more ghetto. It occurs that maybe I should just have inquired to R&M/Pacific about a DD specific replacement swingarm. Works a charm, though. Pix to come.
This was the third attempt. Second was removing one of the bolt/nuts that hold the polymer pad to the crossover piece on the chainstays, and substituting a 5mm cable adjuster. Two-fer -- with a nut on the back, it acted as a cable stop and held the pad in place. Immediate issue was cable rubbing the chain in some gears where they crossed, especially in top gear of the hub where currently I have a bit of slack. Solution was to zip tie a short length of cable housing to the swingarm and run the cable through that as a guide to keep it off the chain. Moment of truth: fold the rear under, SUCCESS!!! Wait... lesson learned, do the complete fold. DRAT!!! Seatpost catches on some part of this setup, will not insert all the way to hold the swingarm in place. Dang.
Which led to a third try that worked. I continue to be amazed at the tight tolerances and engineering which went into the Birdy design.
Pix:
So the stop at the top is some bike part maybe someone can ID, which I found in one of our smallparts bins at the shop. Round with a flat on one edge; on the back it's square and sits nicely within the tubing; 5mm threaded hole. Random 5mm cable adjuster, and you don't see it here, but a locking nut on the back. I won't be using this as an adjustable stop. It's held by tension, nothing holding it onto the bike, but even with the cable at full slack in top gear, it stays put well enough. I can slide it up and down within the slot, doesn't seem to have any effect on shifting.
Simple drilled hole where the cable comes out. I bought the bike used, no warranty to void. If it ever starts cracking due to me drilling holes in it, my bad, and I'll beg R&M/Pacific to allow me to pay for a new swingarm.
Works great, no shifting issues, full foldability. Third time's a charm!
So yeah, now I got a 3x7 Birdy with which to tackle my commute. There are a few hills where this will be useful. Not that I couldn't have suffered them with the stock 1x7 gearing, but I like the enhanced gear range. The cass which came with the wheel was a rather narrow range; I swapped out the stock cass during replacement.