Steve McCaw, mechanic here at Eastside, asked me to build a frame for him after he realised that his Specialized Tarmac didn't fit him as well as it used to. His position has changed due to a bad back, probably caused by years of training and racing in this position.

Steve wanted a bike that handled very much like his Tarmac, but with higher handlebars and a slacker seat tube angle – his position has basically rotated around the bottom bracket. He wanted it to feel like the classic steel bikes of his youth under pedaling. We decided to use Columbus Zona main tubes with 22mm round-taper chainstays and 14mm Columbus SL pencil taper seatstays.

I usually TIG weld my bike frames but this winter I challenged myself to get good enough at fillet brazing to build a bike. I've always loved the look of a fillet frame and so many great bikes have been built this way - classic Claud Butlers, Tom Ritchey's excellent road and mtb frames and Scotland's finest – Shand. So for most of December I could be found in the basement filing and brazing practice pieces together.

We finalised the design using RattleCAD, a powerful if tempestuous bike design program.

Eye friendly version

Then it was time to cut the tubes. One of the main things that determines how straight a bike is, TIG or brazed, is how tight the fit of the mitred tubes is before joining. If there's any more than the width of a rizla between the tubes the join will pull that way as it cools.

So the joints need to be this tight, exactly the right angle of mitre, exactly square on the tube and the tube needs to be the right length. Kinda tricky! And very time consuming to get right, particularly with hand tools. But the challenge is half the fun :D

I hope you read part II, coming later this week.

Andy