I had this same problem with pain in wrists, as I sat on saddle all of my upper body weight was on my arms.
How did I know apart from obviously feeling it?
With hands on handlebars and in normal position (lean against a fence or something) remove arms from handlebars and see what happens to your upper body. If you have to stop yourself going forward it confirms pressure on your wrists supporting your upper body.
The answer is to tilt your seat slight pointing upwards. Then when you repeat the above most of your weight should be on the saddle and your arms and wrists should have to support less weight.
It worked a treat for me.
I read all the advice on riding position and it help (definitely listened to it regarding the knees) but I think I read that your weight is supported in various proportions by the saddle, pedals and handlebars.
I threw that advice about the handlebars out. I don't want a great deal of weight on the handlebars.
The best advice is "take all of the advice given, try it and see if it works for you. Continue trying until you find what works for you." That is all that matters.
in this thread I found the ultimate riding position for me
http://www.cyclechat.co.uk/forums/showthread.php?t=34885
but most of the posters in it disagreed with me. Were I to follow that advice blindly I would be in pain now.
Thankfully, it works for me so I'm happy.
do the same, listen, evaulate, try, decide and repeat until happy.
the good people on this forum are all here to help but without the above you'll never find an answer.
Sorry if I appear to rave on a bit. I get a bit passionate at times!!!!!!.