Look up "cycling palsy". It is caused by over use of the hands holding the bars. It is a combination of the bike fit, core strength and long time on the bike. I always had nerve damage after long rides that lasted for 5-6 months. What minimized this problem for me is sitting on my long distance bike all the way back and unloading my hands(saddle tilt is important) and working on my core strength off the bike. Even with a perfect bike fit and strong core it is still important to pay attention when on the bike, make sure the elbows are not locked and you are not sliding forward on the bike while riding, especially when your are fatigued.
Last edited by Andrey; 01-31-23 at 09:26 AM.