It's also worth noting that it's possible to get numbness from things like gloves that impinge on the nerves. Not sure how that happens to the ulnar nerve, but I had a setup that would push on the carpal tunnel. Most cycling specific gloves have a gap there so it doesn't push on the nerve. Adding too much padding can cause this problem. The ulnar nerve probably is easier to push on. I think people with good setups are more likely to have ulnar nerve related numbness.