New jigger

 
I've yet to find a piece of bamboo that is straight. Sure, a lot of them LOOK straight, but really, there's always half a degree here, half a degree there. The most annoying ones are crooked in 3 axes at once. I try to avoid that as best I can, but sometimes there's a perfect piece that needs taming.

The seat tube on Vinod's bike was massively stout, and I had to find a way to ream the insides out to fit the seatpost. That would have been problemmatic, since this was one of those 3D curves (though subtlely) and by simply following the inside profile of the culm, the seatpost would have been cockeyed. Enter this jig: with a piece of my tube notcher, and some select hole saws, I was able to construct a jig that will ream out the dead center of the seat tube every time!

Aside from me forgetting that I'd left the cotter pin in the spindle when I first used the thing and smashing a bloody gash into my second handiest finger (right index, in case you were wondering) it worked great.

More progress

 
Headtube joint laid up, and strong as I've ever made. This one went together really well, though I have to remember that when the air temp is 84 degrees, the epoxy comes out fast, and hardens up quick. I almost ran out of time to put the layers on the headube as the cup of resin I'd mixed up went exothermic and started setting in about half the time. In the winter I have to hold the saturated sheets in front of a heater, but today, no need.

Seatposts go in here

 


After a bit of careful reaming and sanding with my new tool, the seatpost sleeve goes in nicely.

BB joint

 
The seat tube is a fabulous piece of aerodynamically grown bamboo. It's got an ovoid cross section and is super stout, which will make for an excellent end product. I was able to miter the downtube/seat tube junction so that the rear portion of the tube overhangs and will mesh nicely with the square section of the chainstay unit. It's gonna be swell.

More progress, slowly

 
Spent a couple of hours working on Vinod's bike last night. These pics were taken after the final fitting of the tubes, and before I tacked the joints with epoxy.

foam it up

 
Filling tubes with expanding foam is a good way to prevent crush damage and also stiffen up the tube for general riding. I used a two part, 4lb per cubic foot mix that has good general volume stability without being overly heavy.

Aerodynamic bamboo

 

Working on Vinod's bike now and I have this really cool segment of "aerodynamic" bamboo that grew in an oval shape. I'm thinking of using it for the seat tube since it's both really beefy and also has an interesting profile. I'm always leery of the torsional stiffness of bamboo after my first bike turned out to be kind of a bamboo noodle. The addition of expanding foam, plus the ultra-dense nature of these culms should alleviate that problem though. V is a big guy, a former rower and rugby player, so I need to make sure that the bike will stand up to the test.