Originally Posted by Iride01

Are you handlebars too wide for you? For my size bike, 56cm, it came with a 42cm wide bar. My previous bike I built out, I also put 42cm bars on it as that is what matches the width of my acromion process. Which is how some say to size bars. I never was completely comfortable with that width and eventually got a feeling like shin splints in the back of my upper arm just a little above my elbow. I changed the bars out to 38cm which is the bar width of two of my other bikes. One that I'd rode for over 35 years. The annoyance went away.

If you are keeping your arms too straight, then that might also play a part. If your fit is stretched out, you can usually have straighter arms and not have the bumps and jolts to the bike shared too much by just your arms. But if you have a more normal fit, you really need to keep a good bend in the elbow to allow those bumps and jolts to be shared more fairly by the rest of your body parts and muscle groups.

Also, when you go over bumps, it's helpful to unweight your butt from the saddle a tad. As well, if your position is balanced as you unweight the saddle, then you should also be able to unweight your hands to also keep from having to absorb all the bumps and jolts. If you aren't doing this, it'll take some practice. After a while, it just becomes natural and hopefully you will find yourself doing it without even having to think about it.