I’ve had a lot of trouble with pins & needles. There seem to be all sorts of causes, so what works for me may not work for everyone.
I suspected carpal tunnel syndrome and had the tests at hospital. Although I’ve got “moderate” in one wrist and “moderate severe” in the other, my doctor didn’t think that was the cause, he suspected a neck problem.
I tried Specialized Ergon style grips, they made no difference at all.
I tried all sorts of stem and handlebar combinations. Sitting more upright helps a bit.
I’m fairly convinced now it is a neck problem. If I start to feel it coming on I make a concious effort to unhunch my shoulders and sit upright briefly while shaking one hand at a time.
It seems to come on mostly when riding easy flat tracks on the singlespeed. I reckon that because there is little resistance to the pedals I am transferring weight from my feet to my hands.
Bar ends help by allowing me to change my grip frequently.
I’ve got carbon bars on one bike and aluminium on the other. I can’t tell the difference.