Sun 24" Traditional Trike Help I am trying to figure out if I need a 23" or a 19" support bar to install a western saddle for my mothers trike.  Below is a picture of the measurement from the frame mount to the old seat.  I estimate I will have to lower the seat by two inches to accommodate the new style.  

Can someone provide  guidance on how to figure out the right size before I order?

The bike has 24" wheels...  



This 19" bar or the 23" model? I could not add the 23" model picture because of reputation point limitation...
The 24" Traditional trikes use the 19" support bar. The 23" versions are for aftermarket longer seat posts. So if that is the original seat post, and your mother is not extremely tall, then you need the 19". 

The 23" comes into play for taller riders so their knees are not smacking their chin and requires the use of a longer seat post than what comes with the trike.