At the beginning of May I decided to make a new bike using a Pinion P1.12 gearbox. At the end of June I rode it unpainted for a weekend in Nelson. I took 33500 time lapse photos of about 75% of the time I spent making the swingarm and assembling with the front triangle, which I made first, before deciding to make this video. I guess that means I probably spent about 60 hours and 20 sheets of sandpaper working on it.
The first thing I did was draw a rough model of what I wanted to make so i could guess how it would pedal, indicate where clearance would be tight and get an idea of how I wanted it to look, as well as define the geometry I wanted.
Also it has dual dropouts, so I’ll be able to fit 650DD tyres on when they are available, after all it’s nearly 2016. At the moment it is 16″ cs 65ha 75 effective sa 24″ effective level tt 160mm ft and rear travel 13.3″bb
I make up very simple jigs, and rely on aluminium extrusions being straight enough for a push bike. I’ve also made a few aluminium mandrels to wrap headtube, seat tube and pivots around. These mandrels also get bolted into the jigs to hold their parts in place. You get to see the headtube mandrel being used to align the shock yoke mounts.
I use a variety of uni and weave carbon cloth with a wet lay up – epoxy resin. This bike being made in winter meant it was often cold, which really helped by slowing down the curing of the (24hour) epoxy during the very slow layup in the video. The first layup in the video was compressed by vacuum pump and bag, the second by wrapping in bear brand (it is important) electrical tape. If you buy cheapo tape brands they don’t stick to themselves as well when covered in wet epoxy.
I printed a 1:1 scale drawing to check and build to. I then cut out the foam to rough shape by a hand wood saw and later sand it to shape.
For thread inserts, yoke bearing mounts and the swingarms bolt to pivot parts I stick blocks of g10 fibreglass board in. The same is inserted in the front triangle where the shock mount plates and bottle cage bolts are.
I need to get much better dust prevention mask etc, apparently the gear I had was enough to shorten my life significantly, and make the last years of it rather uncomfortable, so if you are going to try buy a good respirator mask/ goggles and the likes before anything else.