I'd delighted that Longstaff is offering trikes and conversions, and hope that I will never need one. My reasons are not complicated, and are based on a lot of riding.
Dan Kehew asked: What about riders who are getting older? I was talking about the NAHBS weekend with my 60-something boss on Monday, a fellow who rides about 10 mostly-paved miles once or twice a week. He really enjoys it, but he's facing the fact that a fall will cause more problems than ever before. He was delighted to find that he could convert the bike he enjoys now into a trike and not look like a dork riding a "shopper trike."
With all due prejudice, a trike based on a conventional bike's geometry has all the elegance of a mackeral trying to row. The front end of a bike is designed to steer away from the crown of the road, toward the ditch. It's part of what makes it rideable, eh? The Jack Taylor trike I used for a while was pretty vigorous in chasing the right curb or ditch. In addition, the single-front-wheel design with high center of gravity is inherently poor at resisting turning over, and requires rather surprising skill to master while turning assertively. Great fun, but not for the faint of heart.
But, there is more: Phil Sieg asked: Is there any inherent advantage to a two-wheel drive version that would cancel out the added complexity, expense and maintenance?
To me, for for others who ride on the right side of the road, the British design, driving the left rear wheel, is logical (for England), but so bad as to be amusing for the rest of us. On a crowned road, weight shifts ot the outside wheel. In the US, weight shifts to the right wheel. You can unload the (uphill) drive wheel so you can spin it. And get nowhere. BTW, as a compensation, it is pretty easy to learn to ride on two wheels, front and rear drive, if they're adequately braced. A conventional differential would not transfer any power this way...
When it gets to that time, I will grouchily slide off my vintage upright onto a "tadpole" recumbent (2 front wheels, one drive wheel in back). Very stable, very fast, and an absolute hoot for sliding around corners. Of course, they are nearly invisible, so I might not ride one on the roads very long. :-(
harvey "totally unprejudiced, just punished by experience" sachs mcLean va