Thanks for your post and question. To begin with, with a handle of "Rubber Harley",.... guess what? Yes, I ride a Harley every day and a lot of days and nights in latex, of various kinds. Yes, the first time I got on a Harley and with the vibrations I got an immediate hard on. I ride each and every day.... and my wife absolutely loves it!
Oddly enough, she rides with me all the time, and she says she doesn't get sexually excited about riding, but does get sexually excited about sitting behind me and reaching around my waist and feeling my hard on through my leather chaps.
I get a hard on by riding, but you slip on my leathers and maybe a latex jock strap, let me tell you, my dick is ragging hard like concrete! And I love it.
My wife knows when I pull into the driveway... well, she as might as well, bend over and take it!
Why does this occur? I don't know, but I do know what it does to me. I'm on my second Harley and have over 100,000 miles behind me. Just love it! We travel the roads all the time and have just wonderful great sex at the end of the day.
Regards, Rubber Harley