Numbness in the hands and fingers while riding is caused when there is too much pressure in two important nerves in the hands, the ulnar and median nerves. When the ulnar nerve is affected, it causes numbness and/or tingling in the pinky finger and pinky side of the ring finger. When the median nerve is affected, numbness and/or tingling occurs in the thumb over to the middle finger side of the ring finger.
Often times, hand numbness occurs when there is too much pressure put on the hands, which is caused by incorrect saddle position. A saddle positioned too far back leads to an overstretched positioning, putting more pressure on the upper body and hands. With an incorrect saddle tilt, even by just a degree or so, there is an increased pressure on the hands and upper body.
When the median nerve is affected, most often by too much pressure in the hands or by gripping too hard on the bars, numbness and tingling and loss of hand strength spreads from the wrist to the thumb to the ring finger. This is more often caused by incorrect saddle tilt. Often times when a saddle feels uncomfortable, the first way to fix it is to angle the nose down to relieve pressure off of sensitive soft tissue. The biggest problem with that adjustment is that it now shifts the pressure to the hands, increasing tension on the median nerve. By finding a saddle that is comfortable in the correct position, the riders’ weight can now be evenly distributed between the saddle, handlebars, and pedals.
One cause of ulnar nerve stress is an incorrect bike positioning. When the ulnar nerve is over-stretched, caused by over-reaching or extended reaching in the drops, numbness and hand weakness spreads through the pinky and ring fingers. When the saddle is positioned too far back, or when the rider is positioned so that they are over reaching to the handlebars, the nerves are not only overstretched, but there is more pressure being applied to the hands. Another sign of being stretched out on the bike is lower back pain. Be conscious of the pressure points on your body and make sure your fit is correct for your body, your bike, and your riding style.