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Building a Bicycle

By Grant (L.N.R.)

 This cannot be a complete workshop on the building of this bike, as the item in question was built in two days, as a source of light relief from some repetitious work. The method was all in my head, and no pictures were taken during the time of construction. It is certainly no engineering piece as close up pictures reveal, more to convey the impression of a typical, plain, fixed wheel cycle.                                                                                    

I have a custom built racing cycle, and all measurements were taken from it. Firstly, a pair of rims were machined up from 32mm diam. brass tube. They are 1.4mm wide and have a “U” shaped groove cut in with a parting tool. They were then drilled around their circumference with a No.68 drill at guessed 3mm centers. No centre pops, a punch won’t fit. It later turned out to be an even number of holes, important though I didn’t realize it at the time. Axles of 20 thou. hard brass wire, with a hub of 1/16th brass tube 4mm long were cut up. Next the very important and precise jig to spoke the wheel in, consisting of a piece of wood with a hole to take the axle, and a 32mm. diam. circle drawn around it in pencil with a compass. Told you it was complicated.

    The axle with hub was put in the hole then thin brass wire (10thou.), obtained by unwinding 7 strand picture frame wire, was passed through a hole in the rim from outside, around the axle just above the hub as in the diagram, to approx. the 90deg. Position, then out through the nearest hole. Each wire was left sticking out of the rim by about 6mm. or so and soldered. Same thing across on the other side, giving 4 spokes at 90deg. approx and all going to the one or near side of the hub. Next wheel carefully turned over, to make 4 spokes the same way, splitting the other spokes, i.e. 45 degs. out of phase, but going to the other side of the hub. 

Pic. shows spoke method, cross section of axle and hub (Blue/red), and cross section of rim (Green).

    At this stage the wheel needs to be trued up. By mounting it carefully by the rim in a small vice, offending spokes were tightened by melting the solder and puling on the spoke with pointed nose pliers, or tweezers, and spinning it between the fingers to check for trueness. Yes, a certain amount of burnt fingers, unfortunately nothing holds things quite like fingers. Note, at this point I did not solder the spokes at the hub. You need to have the hub central, viewed from the front, and of course centred in the circle of the rim. Once this is achieved, it’s all down hill. It remains to fill in the rest of the holes around the rim, remembering to move from side to side as well as round the rim. Final tweaking of spokes may be required, to trim the wheel, and the spokes can be soldered at the hub to trap the axle. When complete the ends of the spokes were snipped off, and most of the solder cleaned out of the rim with the Dremel, mounted with a diamond cut off disc about .75 mm. wide, to leave a groove for the tyre.


You now have a wheel that looks like this.

    The front forks were bent up using 1/16th brass rod, corrected for length, then a small flat filed at the bottom, on the inside and outside, to provide a flat to drill the hole for the axle. This is best drilled from both sides, first, then the drill run through to true up. A shaft (1/16th again) for the forks to turn on was silver soldered in place, and left over length. The various other pieces for the frame were made up from the aforementioned rod from measurements taken from my cycle. The bottom bracket, and head stem were cut from K&S brass tube (3/32 diam.) for the pedals and forks to turn in. The stay tubes from the saddle to the rear fork ends were made from 1/32nd rod and SOFT soldered, there being enough strength in the frame now. It is probably feasible to soft solder the whole frame in hindsight, though it would be less strong, with the danger of melting one joint, while soldering another.

    Handlebars, from rod, pedals and cranks, bent up from wire, front sprocket machined from 1/2in. rod to 7/16th diam. with a groove for the chain to sit in, drilled with five holes, then filed to represent the spokes. All soldered to a shaft to pass through bottom bracket. The saddle started as an experiment in hardwood. Filed to shape with a bit of Dremel work, mounted on the saddle post at the front, with a frame and two HO,  Kaydee coupler springs for suspension. One last thing, two 1/16th  rubber “O” rings for tyres. And that's all there is to it, something you should do only ONCE in your life.