Hi Minotaur, welcome to the "fun" house, glad to hear you're back into MTBing.
Regarding your hand numbness - I kinda get the feeling there aren't many mtbnj members who fall into our "special" category,... those with AARP eligibility
. I'be been MTBing since 1989 and over the years have definitely noticed how differently my body parts react to riding, whether MTB or road.
I use handlebar grips that have a soft cushiony feel. I've had them quite a while but unfortunately haven't been able to find them anywhere lately. I would definitely try the Ergons, I read nothing but good things about them. I'm thinking of putting them on one of my bikes.
DON'T let the fact that you don't see many MTBs with bar-ends keep you from using them. Your bike is YOUR bike and set it up whatever way that works for YOU. I have them on all of my MTBs, which I also sometimes use on the road. Being able to change hand positions relieves some pressure and lets the blood circulate more thoroughly. And I find grabbing the bar-ends when climbing helps me get up the hills easier.
Another thing I do is wiggle my fingers from time to time while still holding onto the bars. Obviously this is much easier to do on the road than the trail. And on flat, smooth sections of trail I'll take one hand off the bar and shake it back and forth from the wrist, again to keep the blood moving. I've gotten to the point where I do these things automatically, to prevent numbness or cramping fingers.
Riding on the road your body is pretty much staying in the same place the whole time. While out on a trail you're using a lot more "body english" to maneuver the bike every which way. That may redistribute some of the pressure on your hands. Also remember to keep a slight bend in your elbows and use your arms as shock absorbers when on the road, and not put your upper body weight onto your hands. Also, if you're recently getting back into riding, it's going to take some time for your body to adjust to it all. You seem really gung-ho about riding again, which is great. Just remember you're not 20 any more, and I don't mean that as a bad thing
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Sorry if I sound preachy about all this, but I just wanted to share some things that work for me. And if you work in Monroe, there are some trails in Thompson Park in Jamesburg. It's not big, or well maintained, but if you need a quick "fix" it might just do it for you. Park near the dog park area.