Cockpit setup, anything to avoid?
 

I recently invested in a new mnt bike. My old bike never gave me any issues with comfort, but my new rockhopper is just the opposite. My hands go numb very early in any ride, I switched the handlebars from my diamondback but it only helps a small amount. Before moving the bars I pulled out the tape measure, and though the rockhopper is a 19inch and my old diamondback is an 18inch, the distance from the center of the bars to the seat post was 3 more inches on the diamondback. I have taken the rockhopper on the best singletrack close to my house, and I am very comfortable on the trail, (slow but I feel fine on the bike), except for the numbness. I switched the longer stem from the DB to the RH as well as the bar which had less sweep to it.

Finnally my question. I am looking to buy maybe a thompson set back seat post to get me closer to the dimensions that where comfortable on my old bike as well as maybe getting a longer stem and some bars with no sweep, is there anything I should avoid as far as weight distribution or whatever? I feel kind of funny considering that my old off the shelf bike felt better than my new LBS bike, but I keep telling my self that the heavier beefier frame will handle my 225lbs with a bit more security.

So you have a close cockpit and more upright position on your new Specialized than you did on your old Diamondback? Hmmm... Wierd.

How does the handlebar drop (handlebar height in relation to the saddle height) compare between the two bikes?

Have you played with your handlebar rotation within the stem clamp? Sometimes just a few degrees of rotation can make a huge difference towards eliminating "hot spots" on your palm. You want to have an even pressure distribution across your hand.

Setback posts are great for correcting your position in relation to your crank. But moving the saddle rearward to make a cockpit adjustment at the expense of your knees isn't a smart thing to do. A lot of guys will cite the "KOPS" method of saddle positioning -- "Knee Over Pedal Spindle" -- but this rule is unscientific. It's a good starting point, but may vary from rider to rider. Point is, set the saddle fore/aft to where it works for your riding, and adjust the stem for cockpit adjustments (you can see why a frame's Effective Top Tube length is such an important measurement, especially if you have a preferred stem length).

FWIW, Thomson makes the best seatposts in the business, but their lay-back models don't offer as much offset compared to most of the other brands out there. Easton, Race Face, Salsa and others can offer 1.5x to 2x the setback of the Thomson's 16mm.

Great info Speedub, thank you.
I can not be positive about the seat position because I have switched so much around, but I think I rode the DB a little, (.5 in to 1 inch) lower than the RH is set-up. I pick my son up pretty often from day care in his burley and 3-5 days a week for a couple of months at an hour round trip and I never had the hand fatigue I have now. The RH came with 9 degree sweep, the DB has what must be 5 degree and so swithing that and the longer stem did help a little. One thing I always notice when riding the road on the DB was that I wished for a bit more room to move back to get really comfortable. Being a novice I did not know what to look for when I purchased the RH. I like the size of the bike from a handling perspective, every time I go out I feel more in control of it, but I think I need to stretch the cockpit a little in both directions so that when I am in the saddle it is a better match. I know a lot of people talk about fit, now I wish my LBS at least discussed it with me, but you live and learn and I do like the bike.
I will tell you though, that DB frame is 6061 Al, light as hell and nimble, I almost want to buy a usable fork for it and give it a try on a rough singletrack, just to see if it would hold up.