If you’re fortunate enough to make it along to the North American Handmade Bicycle Show in Sacramento this weekend, make sure you stop by the University of The Fraser Valley’s booth. On display will be the 1888 Whippet full-suspension bicycle that Paul Brodie has re-constructed by hand, from scratch. It demonstrates his skill as a master frame builder, which he imparts to the students who enroll at UFV’s Framebuilding Course. If you want to own a real piece of history that’s as much a rolling work of art, bring your checkbook. It’s for sale.
Here’s Paul: “The Whippet bottom bracket is not so simple. It holds the lower spring mount, and also incorporates the swing arm pivot. On the far right is the ‘spoon’ brake, used against the rear tire. The Whippet has no front brake. Good luck if you’re going downhill in the rain!
More metal: Two chunks of steel, a thick walled tube, and a couple of sealed bearings. I decided it would be easier to make a 3 piece BB, rather than carve it from solid metal…”:
“This setup is on the milling machine. The vise holds the blocks and the digital readout (not shown) makes it easier to locate centers for the bearings and swingarm pivot”:
“After bandsaw visit, the bottom bracket was profiled on the rotary table, filed and sanded smooth”:
“The bottom bracket got an internal seat tube lug TIG welded on. This way, when the seat tube is brazed on, there is no warping to the shell”:
“Start of the spring mount. I roughed out a shape on the lathe, and then cut the sides on the bandsaw. I didn’t have a drawing, just an idea of the approximate size”:
“Seemed to work out OK. Sometimes I just grab a piece of metal and start making something. I don’t always know the final shape, but it evolves as part of the process”:
“The spring boss was machined from 4140 steel which has quite a high carbon content so it’s not the best for TIG welding, perhaps. It was easy to braze on with nickel silver”:
“The next step is a lathe job. We need a ‘spigot’, a tube is machined so the bottom bracket can be ‘lightly tapped’ on, and the ends machined. This makes the ends parallel with each other”:
“This is where it all comes together. A few very small TIG tacks will hold the three piece bottom bracket assembly for brazing with the nickel silver rod”:
“Right after brazing and obviously still very hot. It’s sitting on a heat brick; best just to let it cool slowly. Never quench it in water”:
“Back in the lathe to bore the holes for the bearings. In Machinist Talk, ‘size on size’ would be good here. This means using a micrometer and a telescoping gauge to measure the inside diameter of the BB to make it EXACTLY the same size as the bearing. This would result in a ‘light press fit’, meaning the bearing could be tapped out without too much trouble”:
“That’s it for now. You can see the swingarm as it fits in. The shaft is 7/16″ diameter”:
Paul teaches Framebuilding 101 at the University of the Fraser Valley. For more information on the course, where you can learn how to build a steel framed bicycle using Paul’s original jigs that have built over 4000 frames, visit the UFV website.