At a recent club meeting of the Des Moines Woodworkers Association, Shawn Brown showed off a new bicycle he recently finished. I asked him to tell me more about it. I think you’ll see from the photos the fantastic job he did. What follows is Shawn’s story on how the bike came together.
I have been interested in bicycles all of my life. One day when I was looking up local bike shops on the internet, I ran across a video of a wooden bike. The builder, Masterworks, was from California and had sold a bike to someone on the East Coast. The builders were transporting the bike to the new owner and happened to stop into IchiBike in the East Village on the way through. I have been woodworking for several years and thought it would be fun to try and make something similar.
I have used Sketchup to design a few woodworking projects and decided that would be a good way to “build” a virtual version of the bike to figure out some of the design issues up front. I liked the basic shape of their bikes and found a side view photo of one that was shot almost straight on. I imported that photo into Sketchup as a background layer. I knew that Masterworks used a 26″ wheel on their bike, so I zoomed the background image up so the rear wheel was 26″ diameter. I then traced the main frame components to give me a rough outline.
I wanted to build something more aggressive looking. More in the style of a Chopper motorcycle. Masterworks builds a wooden fork, which I did not want to attempt, so I found a Chrome Triple Tree bicycle fork on Ebay. It gave me the length and style I wanted, but required modifying the head tube area for a steeper angle to keep the bike level. Masterworks changes the rear triangle area of their bikes with different carvings and styles. For mine, I wanted to go simple and maybe do some onlay wood flames. (I never did do that.) I also wanted a longer rear fender with a turned up lip on the end. And I wanted to use 29″ mounting bike wheels instead of the 26″ that Masterworks uses.
After I drew out the parts in SketchUp, I printed out full-scale plans to cut the parts from. The main frame is ¾” Baltic birch plywood. I drilled out holes in the center core to lighten it up a little. Masterworks bikes are only single-speed with coaster brakes, but I wanted gears and disc brakes on my version. SketchUp helped with laying out the locations of the cables. In the center core I routed out grooves and lined them with aluminum tubing that I could run the cables through later. One of the pictures shows the holes and channel in the core.
I then epoxied on 1⁄8” Baltic birch plywood to the core, thinking this would be similar to a torsion box design and hopefully give me some strength while still being light. I epoxied on walnut to the main frame and used a router with a flush-trim bit to pattern-rout everything down the the core. The secondary frame is ¾” Baltic birch ply with 1⁄8” purpleheart on the inside and ½” purpleheart on the outside. The rear triangle is made the same way. To build out the rear fender, I started with a ¾” Baltic birch ply sanded to the shape I wanted, and then epoxied on walnut to both sides, pattern routed it, epoxied on purpleheart, pattern rout, epoxy on padauk and pattern route.
The part I was most worried about is the connection at the headset. With the long and steep rake of the forks, I thought there may be a lot of stress at that connection. What I did was to cut notches in the main frame that the plywood fits into and alternate the ply with wood. This created a sort of internal tenon joint that seems to be holding up. There is a photo where I traced lines that show what I am talking about. After it was epoxied together, I drilled out a hole and epoxied in an aluminum tube for the headset bearings and races.
I had to make some aluminum mounts for the rear wheel connection. That was a challenge since I don’t have any metalworking tools besides a drill press. So I spent a lot of time with a spindle sander and files. There are a few places around where you can buy bike frame parts for building your own frame out of steel or aluminum. So the only part I needed to make was the mount that attaches to the wood frame. It is the small silver part at the rear wheel in the side view photo that is bolted into the wood. I was able to purchase the actual dropout where the wheel and disc brake mounts.
I also epoxied in a pre-made, aluminum bottom bracket where the front crank is. That was as simple as drilling hole in the main frame the correct size and using epoxy to secure it in place and keep it centered so the chain would line up correctly. I had to add a chain roller to keep the chain from contacting the frame in certain gears. It really does not add much friction when pedaling.
The main frame and secondary frames are wedged through tenons in the rear fender. There is a photo showing the connection by the rear wheel.
The seat post is a aluminum tube welded to an aluminum plate and clamped with a couple of bolts and threaded knobs. It is very adjustable, since I can slide the whole thing back of forward and the seat post can be raised or lowered.
All of the joints are epoxied together. I also used sex bolts to strengthen the connections. Maybe not so much to strengthen the connection, but more as a safety factor. If the joints give way, maybe the bolts will hold long enough to get stopped.
All of the bicycle parts are standard off-the-shelf items I sourced on the internet. The wheels were hand-laced by me. I wanted large tires to give it a muscle bike look. The rims have cutouts in them to save weight. The red bumps are a rim strip that keeps the innertube from poking through the holes.
The finish is a oil-based clear gloss spar varnish. Hopefully the UV protection will keep the wood from fading too fast. I have been working on it for about 18 months, whenever I had time, nights and weekends. I would estimate probably 200 hours into it.