Originally Posted by cat0020

I consider the priorities of a customer before I make suggestions to what kind of bike, trike they might need.
Just a blanket statement that claims (delta) trike are "less stable", seem regardless of a customer's needs or priorities.

Setting expectation for customers while they are shopping for bikes, trikes or anything else is a responsibility of any knowledgeable sales person.

If a 80-90 y-o is looking for a trike, I would ask if they have mobility issues, whether they can get in & out of their cars easily,
or whether they have enough strength themselves to maneuver the trike when it's not being ridden.
Determine the parameters of their needs & priorities before suggesting which trike (or quad) they should get.

Majority of 80-90 y-o that I encounter, are not so concern about speed or taking corners at speed while cycling.
They want something that's easy for them to get in & out of, don't have to crouch down low to get into the seat.

Bicycles require balancing, not many 80-90 y-o are going to be able to ride a bicycle regardless how much they think they can or how fat the tires they have on their bike.
I would forewarn the customer of instability issues that may occur during cornering,
explain & remind multiple times that body lean while cornering is key to remain stable on the trike; before they even get onto the trike.