Some "rail", some "fail" :)
I'm a student of excellent mountain bike riding. One of the ways that I learn and (attempt to) improve my own riding is to observe others. This time of year, Thursdays are my favorite day of the week as the weekly Wednesday night Sprague Brook race series is happening and Ron Grucela is shooting pictures and sharing them. I've bought some pictures from Ron in the past and I highly recommend that you head over to his website, check out his work and buy a few pictures!
Now my disclaimers. I am not a professional rider, far from out. These are strictly my observations and opinions and not meant to embarass or demean any of the riders shown. In fact, as you'll see, I've tried to protect their identity. I'm not into XC racing anymore and it's highly likely that I couldn't beat any of these riders in an XC race. So with that out of the way.......these images are from a fairly high speed downhill part of the course. My comments relate to high speed cornering.
This rider is just entering the corner so I can't really comment on his body position or line choice. What I do want to point out is the position of his dropper post. It's not dropped!
I firmly believe that the dropper is the best MTB innovation of the last ten years. I'm to the point where I can't(and don't want to) ride without one. Getting that saddle out of the way is not just for steep, gnarly descents. For cornering, getting that saddle out of the way and lowering your center of gravity is the single best way to improve your corner speed.....and rail!
Speaking of "center of gravity" (CG), did you ever take physics and learn about vector analysis and how forces act along the X, Y and Z axis?
Disregarding the Z axis for this very basic analysis, I've placed the intersection of the two vectors at what I deem to be the riders CG.
His body position on the bike exerts a large force down and to the center of the corner arc and a smaller force to the outside of the corner. If he loses traction, that larger force to the inside of the corner will most likely result in a low side crash.
The smiley face is hiding the riders eyes but he is looking at the red X at the edge of the trail. Maybe he had a slide(loss of traction) that pushed him off line or maybe he's been looking there the whole time.
Either way, you go where you look. Looking toward the corner apex/exit as shown by the green arrow will open up your field of view. Personally, that expanded field of view gives me the sensation that I'm not going fast enough and could probably go faster
The other issue here is that this corner has a very shallow berm that will provide some traction. Getting outside that berm and into the grass will likely lead to disaster! Or at the very least, the cost of a few tenths of a second to his lap time. A tenth here, a tenth there......it all adds up!
In my humble opinion, this rider is using some good technique. He's pushing the bike down into the corner as evidenced by his straight right arm and upright upper body. His CG is over the leaning bike and toward the outside of the corner. He has most of his weight low on the outside pedal.
If he loses traction, the bike will essentially slide toward his CG. Rather than an instant low side, he'll have time to counteract the slide and give his tires that extra split second to find traction.
Keen observers will have already noticed the one detail that I'll pick on. Do you give up? He doesn't have a dropper post!
Yes, he made it through this corner and didn't crash so he doesn't NEED one. BUT, if he could get his CG lower, he could really rail!