This recumbent tandem my wife wants is now preying on my mind. I was doing some full size drawings in the shop a little while ago and the only piece of the puzzle I haven't got figured out is how far the center of the crank should be from the center of the seat ( or some other landmark on the seat) for a given person.. Is there a method or rule of thumb for measuring someone to fit on a recumbent?

TIA

well you can use x seam measurment for starters.
google it you will get a better descriptthan I can do.
I have made a tandem recumbent useing a carbon fiber lugs and aluminum tubing,
Knees hitting the captain seat is what to watch for, it's more of a problem with short stokers.

Thanks! that was simple enough. since the sizing measurement is very dependant on the seat I am going to figure out the seats and buy them before I cut any steel. Any recommendations on seats?

Rick

You can make your own, recumbent seats are pretty expensive.
I made my own carbon fiber ones but thats a bit complicated.
here are a few links for do it yourself
https://www.recycledrecumbent.com/ez1draw.htm at the bottom of the page he has plans
https://www.wisil.recumbents.com/wisil/default.htm this site has all kinds of projects

Thanks again! I saw a couple of the seat plans and that looks pretty good unless I run short on time. Gaerlan (SP) has a pretty reasonable seat assembly I may fall back on. I was thinking of getting this done by June and surprising my wife on our 20th anniversary.