Having had some problems with numbness and/or pins & needles in my forearms riding the RST I was adjusting my Ergon GP1 grips ever downwards to try to reduce pressure on the ulnar nerve - to no avail. (I have mitts with padding on the heel of the hand which supposedly reduce pressure on this nerve.) I then thought perhaps the raised bit at the back of the SJSC bar ends might be causing a problem with the heel of my hands so I bought a pair of Cane Creek Ergo Grip II bar ends.
While fitting the new bar ends I revisited the Ergon GP1 installation instructions and noticed the default position is horizontal. Further, adjustment can be 15 deg down, or 25 deg up ... thinks - they go further UP than down!! By adjusting the grips progressively downward trying to reduce pressure on the heel of my hand ... was I causing excess strain on my wrists?
Dan will be displeased at my non-scientific approach but given this eureka moment I fitted the new bar ends and adjusted the grips to horizontal at the same time ... result is a great success!!!
Happy days, I can ride with straight bars after all! I don't know if it's the new bar ends or new grips position, I suspect a bit of both. I might even yet try adjusting the grips upward of horizontal.
Cane Creek Ergo Grip II bar ends are very very comfortable, highly recommended.
P.S. I've also switched back to 1.6" Supremes, tyres weren't the issue with my hands/wrists either.