Snap, those shots are difficult to judge but I'm guessing you are leaning on your hands a LOT! Your shoulders are hunched up, your elbows are locked out and your knuckles are tilted up. This is usually a sign of fatigue. Get those abs and back muscles stronger and break the habit of riding with your arms locked out. Your elbows are your suspension system on a rigid bike and you're taking all the shock in the joint with them locked out. Flat or drop bars - you must break that habit. If the muscles are strong, you'll feel more comfortable leaning a bit forward to keep your elbows bent and also get into a nice platform position for downhills.

'Nother thought - I use 9 degree bend flat bars on my mtbikes due to pain in my wrists (this means the outer ends of the bar sweep back closer to your body). This keeps my wrists straight in line with my forearms. Not sure what your bars are doing but it kind of looks like you may have the same problem. Everything should be in as straight a line as possible.

Have you had a pro or a very experienced friend do a fitting concentrating on the angle of the brake levers, the bend of the bars, etc.? For your upright position you make want to drop the levers a hair so that the back of your hand and your forearm are a flat plane with your thumb behind the bar. (You hit a bump, just what is going to keep your hand on the bars, Miss Snap? ).

OK, I'm going to look at those pictures some more and mull it over. I do know that over the years friends who've gotten into riding and used me as a mentor have had their locked elbow habits broken real fast. I'm a darn nag when it comes to this because it causes such pain in the elbow, neck, shoulders, etc., etc., etc. I try not to let my friends ride in pain.