A
Alaskavan
Guest
When you get the bottom bracket on there, it will be longer, at least the length of the crank. You need to get a backrest on there too (got any more of those sissy bars sitting around?). When you are pedaling, you will be pushing against the seat back, instead of against gravity as we do on conventional bikes. Bear in mind that it is a totally different riding position, so it will of course feel weird for a while. If I were you, I'd proceed with the build per the instructions, but leave options (and your mind) open for ideas that you may incorporate to improve the thing once you have it working. In the long run, you may want to raise the bottom bracket above the level of the seat. I think there may be possible improvements in the chain line if that's done.