Some interesting information on that familiar pins & needles feeling one often get’s whilst riding, quoted from http://velonews.competitor.com:

” Dear BCSM,
I suffer from frequent tingling in my right hand on longer rides (2+hours). I have had a bike fit at my bike shop, but that didn’t seem to help much. I have had a shoulder injury (torn rotator cuff) for a number of years, but it doesn’t bother me.

Could the numbness and tingling in my hand be related to the shoulder, or is it more likely a bike fit thing? Thanks!

A.Great question!

Hand numbness, also known as cyclist’s palsy, can be tricky and persistent.

While it is possible that your shoulder history is contributing, it is unlikely. More likely is nerve compression of one of the nerves in the wrist. If you’re getting numbness in your pinky and ring finger, it’s probably the Ulnar nerve being compressed. This is the most common due to its location, at the bottom of the wrist, close to the bars and hoods of a road bike.

Next is the Median nerve. This nerve runs in the middle of the wrist and compression can cause the pointer, middle, and ring fingers to feel numb. This tends to be more problematic on a mountain bike, however neither is mutually exclusive.

Radian nerve compression is also possible; this nerve runs through the wrist near the base of the thumb, on the top of the hand.

So why would a nerve in the wrist get compressed? The hand and wrist aren’t very good weight-bearing structures, yet some is required for riding a typical bike. Here at BCSM we see many extrinsic causes of hand numbness, and not all are related to the handlebars. To be sure, bar position can play a role in this, and having the handlebars too high can be just as detrimental as having the bars too low.
http://velonews.com/winthistrip

We also see improper saddle position, saddle shape and support causing hand numbness issues. Rotational orientation can cause hand numbness, too. For instance, if you are sitting with your right hip forward, this can translate to a slightly different reach to the right shifter, and possibly more pressure.

There are some good products to help distribute the pressure on the hands. Properly fitting gloves, cushy gel under the bar tape, even switching to a different-shaped hood or grip can help mask the pressure, but not one fix works for everyone.

Finally, some factors causing hand numbness while cycling are intrinsic. Weak core musculature, insufficient range of motion of hamstrings, hip extensors, or degenerative changes in your cervical spine can also cause hand numbness. If you have a known factor, or have exhausted all of the mechanical causes, seek a medical provider that is conversant with cycling to delve into the medical considerations.

— Sean Madsen ”

This information on numbness is just one aspect of a very difficult issue to resolve but its a place to start.  If this doesn’t resolve the problem then a neurologist may need to be seen to find out where the problem is radiating from eg. old shoulder or wrist injury, with a nerve conduction study.