New Moto Guzzi Door Mats Available Now
There is a horse saddle design, the "McClennan" that was developed about 150 years ago for the US Cavalry. It had that same relief feature, but no padding. When we were kids we thought the slot was a grab handle to climb up on the horse with.
Thanks for all your advice, I'll start by wearing some different pants next time I go out. That diagram reinforces what I suspected about lots of nerve endings in that region. You'll be glad to know that the numbness vanishes pretty quickly once I get off the bike. Its been pretty disconcerting to go to adjust myself while riding and finding...nothing! The first time it happened I shook my pants leg carefully not knowing what might fall out.
McClellan saddle
I don't mean to pick a bone here, but "paralysis" means a loss of muscle function, when the muscle doesn't respond to nerve impulses, or the impulses don't reach it. The human penis has a tissue called corpus cavernosum, which becomes blood filled during erection, but it is not a muscle in the common sense, although it may be developmentally derived from muscle. So, the term paralysis doesn't apply here. The inability to become erect can have many causes, both physical and psychological. In any case, the original poster here describes numbness, not paralysis. Penile numbness is well known among cyclists, and apparently is a temporary condition. More serious is injury caused by one's crotch hitting the top of the bicycle frame during a accident. This can cause permanent dysfunction. Don't let it happen to you!
Airhawk makes a cushion that might help the problem:http://www.airhawk.net/airhawk-r.aspx