Wrist pain can be caused by realy nearly any thing. My left wrist is a wreck any how and my left hand tends to go numb pretty readily. Right now in fact its tingling from resting my arm on my desk while typing.

Just like numb hands a good thing to do to help lesson it or prevent it change your grip poistong now and then and dont be afraid to take you hand loose from your bars and shake it out if you start to go numb.

In my case i started gettign this realy bad after i busted my wrist in high school. So if you have ever busted your wrist near the joint this could easly cause your pain. Other wise it could just be minor weakness or your wrist doesnt like the positon your putting your arm in and just adjust that poistion a bit.

Quick way to find it wait till your wrist starts to hurt then chancge where you grip a little bit.