Comparisons

The basic list of things that I want to change is below:

• Tandem recumbents are very long so are hard to transport and store.
  I want one that can be broken down fairly easily into at least two bits. Greenspeed offer one that breaks in half and another that is dismountable to a couple of suitcases. The ICE X2 does the same thing without using S&S couplings, which I belive are only available to recognised frame builders.
  
  
• Need to adjust easily to let a 6' stoker swap with a 5' captain.
  Ideally without needing to break chains as that can get messy even with White Lightning as the lubricant.Sliding seats both ends, chain tensioner on the front if necessary.
  
  
• GS front chain is very tight
  Use a single-pulley "rear derailleur" to tension that chain. This also lets us move the boom without pulling links out of the chain. Ken and Ian say that the front chain needs to be tight as the forces required to synchronise pedaling are high even for practiced riders.
  
  
• Touring and load carrying
  Build in lots of attach points, and possibly also make racks and panniers to fit under seats.
  
  
• Custom panniers don't fit other bikes.
  Try to make it take standard panniers where possible. Especially rear rack ones. Use gear tubes like Ian used for PBP under the seats instead of racks. Those are also smaller and don't need racks, making everything a bit easier.
  
  
• Towing things - hard to get a standard bike trailer to fit.
  Use the GS style tow point, make a custom trailer. Use 20" wheels and cheap tubing to start with. Perhaps use a push-on gas fitting as the linkage.
  
  
• Ground clearance and kerb hopping.
  With a 3m wheelbase we need to be 200mm off the ground, and even then kerbs can be hard. Rear suspension would be nice but it makes things quite complex. For the first version stick with a hard-tail.
  
  
• Need a strong frame with no pedal flex.
  Big tubes, bracing at joints if needed. The Greenspeed I borrowed used 44mm tube, they now use 50mm, but I will go with the biggest tube I can get (70mm if I can). Possibly run 6mm tube or something over the top of front the boom joint since that seems to be the weak point on my TriSled.
  
  
• Tube rust in TriSled, presumably also GS.
  Put pair of bidon mounts in every tube. Add fish oil, change periodically. Drain non-sealed tubes regularly. Seal tops of seat tubes. Bonus of this is a surfeit of mounting points for gear.
  
  
• Convert to solo trike.
  Since I'm going to be breaking the trike, can I break it such that the end bits fit together as a solo?

The first step was to measure up the recumbents I had available, and sketch out their frame geometries to get ideas about what is known to work. Having the Greenspeed tandem around was very useful. There are photos as well as gifs of some measurement sketches .