First of all, I have never ridden a DH rig as I am more of an All Mountain - XC rider, so this might might be a really dumb question.
I was watching the Val Di Sole Practice Highlights video (https://www.pinkbike.com/news/practice-highlights-video-val-di-sole-dh-world-champs-2016.html) and I noticed that these top girls and guys hardly touch the saddle.
So my question is: Is the saddle really necessary on a DH rig, especially in competitions? Do you DH guys use it to control the bike with the inside of your thighs, even though you are clipped in?
I don't use it much for control, but it really helps prevent some nasty injuries when I mess up (where I'd be coming in contact with the top tube if the seat was gone)
One more question, inspired by to Lucas-Ault answer above:
Does the saddle prevent your groin/ass from touching the back tire when the suspension is compressed?
I have seen this crash by Catherine Harnden where her pans got caught between the saddle and the rear tire, but in her case, I think the seat hindered her even more by pinning her down:
I recall that happening a lot a few years back, when everyone was convinced a small bike was better. Haven´t noticed this happening to anyone since bikes have grown longer in reach, thus making it harder to even go beyond the seat. In that video, that bike seems massively undersized, otherwise it would be hard to even get that far behind the saddle. It´s also the reason why she feels the need to go that far back in the first place imho. That´s also something i don´t miss about bikes from that era. Hitting jumps felt scary as f*ck cause your sweetspot on the bike was so f*ckin small and there was no room for mispositioning.
If something similar happens to me on my bike, my ass slams on the saddle and that´s it. I have touched the back tire on mine one time and that was because i was tucking down low on the run in to the big Schladming stepup and i hit the little ledge right before the bottom of the run in which resulted in me overjumping it, landing in the compression while still being in a tucked down position. But that was MASSIVE mispositioning on my part, yet i still only brushed the tire for a short moment.
So yeah, if you ride dh, you need a saddle. Whether it´s for a short break to catch your breath in the middle of a long run or just to control the bike when things get rough. Also, have you ever slipped a pedal while railing a corner hard? Without a saddle you´d just hit the top tube...
I sometimes use the inside of my knee/thigh on the seat in corners, it helps push the bike over. Then there's the times it all goes wrong and you slip the pedals and end up with the seat in the pit of your stomach, if the seat wasn't there my balls would end up in the rear shock!