General layout
I need a donor with a steel frame brazed with lugs, out of round steel tubing. This is essential as I want to cut the old frame and use parts and tubes. Since I will be using brazing to join the parts of my frame, sophisticated alloys of Aluminium, Magnesium and other aerospace materials so favored in modern high-end bikes are out of the question. Standard alloy steel is the way to go.
Frame geometry
The rear part of the donor bicycle's frame will be used complete as a module for my new frame. This includes the pedal bottom bracket and the chainstays. Therefore the shape of this module has to fit my needs. The shape of the rear dropouts is very important, as I would prefer a semi-horizontal rear dropout with wheel disassembly to the front. I want to avoid horizontal dropouts with rear disassembly that require adjusting bolts to tense the chain, which are common in many older bikes.
I do no have a use for long 1 inch tubes such as the top tube, seat tube and down tube, as the Pedersen design is based in thinner and longer 1/2 inch tubes. On the other hand, I need a strong head tube, but much shorter than in a standard bike. I need a frame with a head tube that can be cut to the desired length and recycled. For recycling I will have to turn the head tube in the lathe to cut out the old brazed lug. Therefore, if possible, I have to look for one that is best suited for this operation.
The front fork is the most complicated part in the Pedersen construction, consisting basically in 4 tubes assembled in a truss type of structure. The two tubes in the rear of the fork are bent at a subtle angle of about 15 deg, exactly at the point where the fork bracket is located, about mid span of the fork length. I have observed many woman bicycle frames, which in order to replace the top tube on a standard diamond frame use two long and thin tubes from the rear dropouts to the head tube with a slight bending about mid span when passing near the seat tube.
I think I could recycle such tubes to be reused in the fork, being the dimensions and the bending angle very similar to what I need.
Gears and brakes
I want the bike to be functional in the street and also on the road, for longer several days cycling tours. Thus, a minimum of gear ratios availability is to be secured. At least a range spanning from 3 to 7 meters per pedal revolution is needed, to cover from some modest climbing to flat or slight downhill cruising. Getting pedals radius of 170mm or 175mm will not be an issue.
Brakes will probably not pose a problem, as I would rather go for caliper brakes both in the front and rear and they are commonly available in old bikes. They are simple and reliable and fit for the purpose of this bike.
Accessories
The more accessories I can recycle from the donor, the less I will have to search for later on. The handlebars in a Pedersen are along with the fork and the hammock saddle the most conspicuous features. They have this very particular shape, bent in the "wrong" direction, that provide a confortable wrist position when riding. If I might find an aluminium granny-bike type handlebar, I could mount it upside down in the stem and adjust it to match a Pedersen shape.
An old fashioned leather saddle Brooks-style could be recycled for the hammock saddle, if I can find one.
Finally, if I can get a donor that comes with fenders, rack, dynamo and lights, all these extras are welcome.
Having in mind the complete set of specification as described above, I set to search for a prospective donor. This is what I found in the local dump: an old Swiss Condor woman type bicycle from the late 80s with 28 inches wheels and 6+2 Sachs Huret combined derrailleur with internal hub, caliper brakes and the bent "top tubes". General status is acceptable. The only problem being both original Weinmann 700C rims bent. The rear one is most severely bent, as seen in the picture. However, nothing that some patience cannot bring back to true.
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