At that point you probably looked at everything that you needed to do to make a bike. And that’s when things start to get daunting. Before you’ve even thought of the bike, you need to think about the jig. Fabricating a jig with basic versatility and functionality for framebuilding takes time and patience, and the raw materials costs are at least $200 [Instructable example!]. Rapid-prototyping has pushed the costs of pre-made bike jigs from $1000s down to $300 or so [such as the Jiggernaut], but if you don’t know how many frames you really want to make, it’s still money that you aren’t putting towards your first frame.
Next, you need to consider the tools that are specific to typical framebuilding. If you want to learn to braze steel frames, an oxy-acetylene starter kit with everything you need to get brazing is something over $200 (plus the price of an additional gas cylinders, brazing rods, and flux that you’ll use). A TIG welder suitable for working with thin-walled steel and aluminum bicycle tubing is more like $1000.
Next, the materials for the bicycle frame itself. While it would be possible to braze a frame with commodity straight-gauge 4130 (chromoly) steel tubing, it would be very heavy and wouldn’t ride very well - bike specific tubesets are double- or triple-butted to save weight and place extra material at the lug junctions. Bicycle specific tubesets will cost you upwards of $100, and a set of lugs and dropouts is about another $100.
If you’ve been adding up the tally, you’re already at more than $600 for your first frame – hopefully you won’t make any mistakes!
I wanted to design a process for building bicycles that allowed an enthusiast to spend less overhead, less time on finicky details, and put the emphasis on actually designing and making a bike that you want to ride.