You neglected to inform us of what type of gloves (padded/unpadded), if any, you were previously using. How long did you ride before numbness set in? What type of riding surface?
Since those "goat" gloves are unpadded and goat hide is fairly thin it seems a bit counterintuitive that just a layer of goat skin is absorbing much vibration (though some vibration damping is better than none). I prefer uncushioned bar wrap, but ride with handmade gloves of my own design (goat skin left over from making my drum heads) padded with 2-3 layers (depends on actual thickness and flex) of skin versus a single layer thus providing more vibration damping at the palm and better protection to the the backside. Most synthetic gloves do not hold up very well, but my 35 yr old leather (2 layer) palm/cotton mesh gloves are still viable after untold miles. I will say this; do not buy Specialized brand gloves, as they do not last but for a couple of aggressive rides and are overpriced at that.
If you properly maintain leather cycling gloves they will last decades.
I prefer full finger leather gloves (road and off-road); you'll know why after your first hand injury to unprotected fingers or where synthetic material just disintegrates with any degree of abrasion.
You should also regularly change hand position to help circulation and prevent tissue/nerve damage. Riding position and posture will also affect your hand/wrist.
Reducing tire pressure (while keeping within manufacturer's specs) can help quite a bit; especially if not riding in an aero position with more weight on hands. If riding in an aero position you are probably using much smaller tires which are spec'd at higher pressures (generally 90-120 psi or higher; regularly run 140psi) and you defeat the purpose so change to a wider tire with lower pressur specs. Also, running high pressure tires at a lower pressure (again, while still remaining within specs) affects handling/safety, and tire wear/longevity) so I advise against it, and the effect of doing so probably won't be felt to the degree that pain and numbness will dissipate to any extent.
Location: Noosaville, Sunshine Coast, Australia
I ride here on the Sunshine Coast in Australia with gloves on due to the humidity. Reason being was that I crashed once as my sweaty palm slipped off the grip.
I've not had any numbness in my hand or fingers; however, I'm curious if the numbness is due to the gloves or your riding posture. Specifically, the angle of your wrist. Is your riding set-up correct?
I use mechanix gloves, but typically the reason for numbness is due to your stem being too low and/or too short.
I use silicone grips to offset numbness, and the thicker ones work really well. Black Ops and ESI Chunky/Super Chunky.
I'm currently using Specialized silicone grips and they do work.
You should consider increasing your stem length by 10mm or so though and/or go to 10~17 degree rise to improve the bike fit if the numbness is really bothering you.
Again, I would point out that this doesnt happen on bents and trikes. Maybe it is time for a change in what you ride.
I wear cheap synthetic gloves I found in Nepal — not because my hands get numb, but for protection in case of a spill. I keep most of my skin covered except my fingers, since the gloves are half-fingered. I also sweat a lot, so I prefer open gloves to full ones.
The only downside was during colder sections of the Himalayas — the metal brake levers became too cold to touch. That’s the one time I wished I had full gloves or some kind of plastic or rubber sleeve over the levers. :-(