There's a few threads on this already - you might want to do a search ( and we might want to create a sticky)

But- you could get yourself fit to your bike and they'd tell you if your handlebars are too wide.

Flat bars are hard because there's only a few hand positions you can use, you can change the handlebars to trekking or butterfly bars for more hand positions or soma sparrows.

Other things to do - sometimes it's the gloves, if the gloves close tightly around my wrist it sets my hands off, same with ifthere is padding in the gloves.

Is your saddle tilted downwards? i f it is, you're sliding forward off of it and holding your weight on your wrists - you don't want to hold your weight on your wrists. Idealy you're just going to be holding the handlebars gently (do not have a death grip on the handlebars, becuase it will lead to hand pain) with your elbows slightly bent and your core muscles will be supporting your weight... this sometimes takes a while to develop your core muscles for a new position on the bike. you want your saddle just titled slightly downwards - not enough to make you slide off yoru saddle, but enough that the front of it isn't digging into you.

what else? You want your hands in a completely neutral position - when you are holding your handlebars, you don't want your wrists to bend back towards you - you also want to keep that straight line for when you are using your brakes/shifters - so if your shifters are angled so you have to bend your wrists to use them, loosen them and swivel them around the bar.

You can get ergonomic grips - called ergo grips or ergon grips that help a lot.

So try all of that and move your hands around as you are biking, flex your fingers, etc. too long in one position hurts.

If all of that doesn't help, you might want to consider a different type of bike (if you're riding aluminum, the vibrations can contribute to hand pain, and either adding carbon components to kill the road buzz or getting a steel frame can help.)

Ibuprofen is your friend - and once you've started aggravating your hands/wrists, it's pretty important to not sleepwith your wrists bent or your hands clenched