It has been some time now since I purchased my 1973 French Tandem. This great find on ebay was supposed to be a quick restoration project however, the project quickly got out of hand when I realised the bikes origin. Old French parts are now hard to come by and pretty much the entire bike required some form of TLC. So began a full rebuild/conversion to more modern components.
The new wheels meant I had to change the front fork. This was also convenient as the headset from the original bike was beyond repair, and finding one that would accept the old fork steering tube seemed impossible. A 700C steel fork was found with cantilever brake mounts that would fit a modern threadless headset. Conveniently a modern 1-1/8th threadless headset fits perfectly into this frame, finally a part of this build that seems to be on my side! I found a set of cantilever brakes taken from my touring bike and fitted these as the primary stopping power. A quick bit of welding on the rear of the frame has resulted in a disc brake mount for the rear wheel, I will use this at some point if I find that the rim brakes aren’t giving enough stopping power for 2 riders descending.
The main issue I had with the frame was the bottom brackets. Both of the existing units were totally unusable and finding new units to fit the existing frame threads was proving difficult. Some research uncovered some options such as re-tapping and using an Italian threaded design. Other options were to use special brackets that don’t utilise the threads in the frame at all and instead just fasten in 2 parts to each other (like a nut and bolt but with a bottom bracket inside). All of these options were prohibitively expensive, especially when you consider that the rear bottom bracket on a tandem is known to take a bit of a beating and requires more regular replacement.
To get around my bottom bracket issue I decided to cut the old shell out and weld in a new shell that would accept a threaded English bottom bracket. Perhaps not the neatest solution but certainly cheap at just over £6 for each pre threaded steel shell. The front bottom bracket was fairly easy to accommodate, due to it being an elliptical type set up that is pinch bolted by the frame. This allows the sync chain to be tensioned by rotating the elliptic bottom bracket and bolting the gap closed. Some 5mm sheet steel was cut and welded in place to fashion my own version of what the frame came with, only this time with a nice modern thread.
The rear bottom bracket was slightly more of an issue. Care was taken in cutting out the existing shell and then perfectly lining up the new shell in place. This is a highly stressed area on the frame and I wanted to make a neat job of the welding. Some chooking later and the frame is back in one piece, only this time with a modern thread.
The frame and new fork were then sprayed with some Rustoleum using my HVLP spray gun in a rudimentary booth outside, the finish isn’t fantastic but it is certainly a tough coating, ideal for this build. I built the bike up using new cables and some spare parts I had from various other builds. I am pleased with the end result but I am still not used to riding on the back, the lack of control you feel as a stoker is something I will have to learn to love.
We then tried to ride the tandem solo, from the back. here is a video of my house mate Ben attempting the fairly uncomfortable ride.