My God! It actually looks like something

Top View

I know it's a little hard to see, with the stray bamboo pieces, and the 2x3 support the tail. It was hard to get a good view on it in the basement. But you can see the rear wheel fork and the crank in place.

Rear Wheel Fork

You can see here the bolts into the bottom side of the rear fork, that connects it to the hardwood dowel that is bolted to the bamboo. The gray line on the steel is epoxy that seals a cut I made when I though I could get the bamboo itself into the steel. Dumb idea. There's a half-circle cut-out in the top bamboo pole that should keep the rear side of the fork from shifting fore-and-aft, and a bolt that holds the fork firmly into the cut-out.

Crank

Not finished yet, there'll be a second support pole connecting to the second top pole of the frame, but here you can see the plan. The crank is sandwiched between curved cut-outs. The support poles cross, and when the last support pole is added I will pin them together, which will prevent them from spreading and releasing the crank. That and a generous amount of epoxy.

The crank is heavy, and reminds me how much weight I am saving using bamboo. I think the crank weighs more than all the bamboo in the frame!