Hammered Dulcimer design, construction, and unrelated stuff

Saturday, June 15, 2013

Wooden Bicycle

Melanie saw a program from Europe about bicycles made of wood.  She thought it would be cool if I built one, and pestered me enough that I finally started on this.  After drawing the design, I was hooked!  This was a lot of fun to do, and now my head is full of ideas for more.  I was going to call it "Honeydo" because of how she kept at it, but when it was finished, we decided "Re Cycle" would be a better name, because that is what it is, mostly recycled bike stuff.  Melanie being an ex sign painter is designing a logo for it.

The wheels are from a Raleigh 3 speed, these have alloy rims.  Most of the rest of the metal parts are from a 60s Huffy, also a 3 speed, and it had the original twist grip shifter.  The rear drop outs I made from plate steel.  The geometry is taken from the Huffy, and it is comfy old style cruiser.  The saddle is an old Wright's from England which we found for $20.00 at an antique store.  It was really dry, but Neats Foot Oil brought it back to life.  

The way you go about designing something like this is lay it out full size on a sheet of plywood.  First plot all your points; the centers of the wheels, how far apart they are, the center of the crank, and its exact position relative to the wheels.  Then the center lines of the seat tube and head tube.  These are both 71 degrees off horizontal, which is pretty laid back by modern standards, but gives the bike that really comfy, upright feel.  On this bike, these points and center lines are a duplicate of the Huffy, except I moved the rear wheel back an inch.  After plotting the points and center lines, sketch in the frame around them.  I wanted a frame of bent laminations, so I just took a thin piece of wood, and flexed it around the points, then drew around it.  It looked cool right away!  This is the point where you really can see something taking shape, and get excited.  

The main frame is bent lamination of 1/8" Baltic Birch ply, it took about one sheet to do the two pieces 3/4" thick.  I built a frame to do the laminating around, then just clamped the laminations up with glue.  The sheet of Baltic Birch was the only thing I bought for this project except for quite a bit of epoxy.  The rest of the wood was mostly pieces that were laying around the shop.  The laminating was done with Titebond 2, but the rest of the assembly was all done with epoxy.  The holes for the head tube, bottom bracket shell, and seat tube were difficult.  A bicycle is a sort of 3 dimensional sculpture, and everything has to be right in line for it to work, but I got it!  This bike will ride very easily hands free, and that is the test.  After the frame was glued together, I installed a set of wheels and sat on it to see if it was stiff enough because I had my doubts.  The front triangle was too flexible as I had thought, but the rear was good.  So I made the web of 1/4" Baltic Birch ply and glued it in with fillets of epoxy, a standard technique in boat building.  That did the trick, plus gave it a cool look all its own.  Another mistake was the joint between the wood part of the seat tube, and the doughnut for the bottom bracket shell.  It was just butt glued with epoxy, but on the first test ride, it broke.  So I made the large piece you can see to completely surround it and strengthen it.  Next time, the post and doughnut will be one piece.  

As pictured above, the bike is almost finished.  It just needs its logo, one hand grip, and figure out how to get a rear brake mounted.  Other than that, I have been riding it, and it is very comfortable, and lots of fun.  If you want to be anonymous, though, don't ride something like this.  People love to see it.  I have been stopped and photographed.  I've been thinking about carrying a donations jar, and asking for a quarter each time.  Melanie was right, it was a fun thing to do.