How do I size a recumbent bike? Do they come in different frame sizes, like a diamond frame bike?

Question

How do I size a recumbent bike? Do they come in different frame sizes, like a diamond frame bike?

Answer 1

'bents are sized by a measurement called the "x-seam"..

Sit with your back flush up against a wall and your legs straight out.  measure the distance from the wall to the heels of your feet, that is your x seam length.  

Mine is 46" which is normally  too big for a medium or standard  size recumbent, and sometimes requires an X-large.

Most 'bents come in at least 2 sizes.  some may come in 4 sizes; I have heard of a bent frame that can accommodate a 51" Xseam, and a small frame for 40".

Crank arm length can generally be shorter on bents, if that helps any.  

If you can fit in between two frame sizes, I would go for the smaller one, since it would be lighter and have less flex.

Answer 2

The Proper X-Seam Measurement,

Your X-seam measurement is essential when sizing certain recumbents. Many manufacturers have slightly different methods for measuring your x-seam. If you're ordering your recumbent  use this method. If you're purchasing from a shop they should fit you.

Place a 24 inch long board against a wall with the bottom of the board 16 to 18 inches from the wall,  this represents your seat position. Sit on the floor with your back and butt against the board. Your X-seam measurement is the distance from the front of the board to the heels of your bare feet. Setting  with your back against the wall gives you an upright x-seam measurement but  you need to have the reclined measurement as well to be in the correct riding position, thus the 16 to 18 inches or a 60 degree angle.

Depending on the Recumbent most will come with a small, med, or large frame. Bacchetta for example has a solid frame and adjustment is done by moving the seat forward and back, the same with Rans, Tour Easy and others.

Another style would be the Lowrider and other manufacturers such as Actionbent and most of the Trikes come with adjustable booms so you can adjust for your x-seam.

Something to remember that when doing your seat adjustments, changing  the incline or recline  of your seat position for aerodynamics purposes will also change your x-seam distance or adjustment  and you will have too re-adjust the seat position or boom length to accommodate. Hope this helps.