Being relatively new to riding a quality bicycle I did not expect numb palms and butt after riding a scant 5 miles. I ride a Globe Centrum Comp which I absolutely love & was fitted by the bike shop. I thought maybe the handlebars could be raised but the bike shop guy says the stem is fixed.

Granted I am 240 lbs and 5'8''. Will the comfort increase as I shrink in size? Or, do I need to modify the handlebar height for more comfort?

So this is a hybrid bike.? You could get a new stem and/or higher bar. Some times numb hands are caused by too much pressure on them. Gloves and or new grips might help. I like my seat 2-4 inches below my bars, YRMV.

I'm about 6'3" and 250lbs and started commuting a couple of weeks ago. I started on an old mountain bike I had in the garage that had one of those padded seats on it. My butt (and other close areas) would go numb as would my hands on my 6 mile commute. After a few rides I bought an entry-level road bike that came with the smaller seat with every intention of switching the seat out. But after I adjusted to the seat I have no need to change to a cushy one and have no numbness. It was after that that I read in these forums that the cushy seats can actually cut off circulation and cause numbness.

For me, just a matter of having a better seat as well as trying to get the bike seat/bars adjusted as best I could (using info I could find here and youtube) made all the difference for me. I'm still overcoming the burn, and there are still some adjustments to make but my ride is much more enjoyable now.

When you say "fitted by the bike shop" do you mean that they took a look at you standing over the bike and said "that looks right" and maybe adjusted the saddle height, or did they measure your arms and legs then watch you ride the bike on a trainer for a while as they made minor adjustments finally culminating with swapping in a new stem? The former is typical of point-of-sale fitting. The latter is usually a pricy service. The former assures that the bike is the right size for you. The latter assures that everything is correctly adjusted.

I'm guessing you got the point-of-sale approximate fit, which is OK, but it means that you'll need to make minor adjustments for yourself until you get comfortable.

Numb hands and numb butt (assuming that "butt" here is actually a euphemism for something else that went numb) can both be symptoms that you're leaning forward too much. Other things can cause the non-hand numbness, but let's start with this. When in your riding position, you should be able to take your hands off the bar and hold your body in position without feeling like you're going to fall forward. This will vary somewhat based on your core strength, but if the falling feeling is pronounced this is a problem. Often this particular problem is fixed by sliding your saddle back. This may seem counter intuitive, but the idea is that to bend over without falling, you need your butt back to balance your weight. Try it standing against a wall and then again a step out, and you should get the idea.

Once your seat is back far enough that you aren't falling over, you may find that the reach to the handlebars is longer than you would like. You fix that by getting a shorter stem. You may also want a stem that angles up to effectively raise your bars for more comfort. Stem length is a tricky problem because as you raise your stem height, you also need to shorten your effective stem length or the reach problem gets worse. Fortunately, it's not an exact science and there's probably a range of placements that will be comfortable for you.

I could say more about fit, but it gets complicated and subjective very quickly. My advice would be to try sliding your saddle back and report back as to whether or not that helps then ask more questions as you narrow in on the problem.

If you feel like some extra reading, start here:

https://www.sheldonbrown.com/frame-sizing.html

or here:

https://www.peterwhitecycles.com/fitting.htm

The bike is considered a commuter, Globe Centrum Comp by Specialized. https://www.specialized.com/us/en/bc/...1&menuItemId=0

The fit I received at the bike shop was the look over as I stood over the bike as Andy mentioned. Having paid $1000+ I should have been put on a trainer and assessed while riding.

Oh well. As Joe Cocker said, "I'll get by with a little help from my friends." here.

My personal experience (YMMV) is that straight bars give me lots of problems.... wrist pain and numbness. The straight bar position is not at all ergonomical and has been in little general use through the history of cycling. What did help before I changed out to a bar similar to this https://www.universalcycles.com/shopp...&category=2657 (and i use drop bars on my other bike) was to use ergo barends.

I liked the cane creek ergo https://www.jensonusa.com/store/produ...+Bar+Ends.aspx

and lots of people swear by the ergon https://www.jensonusa.com/store/produ...+Bar+Ends.aspx

New rider. New bike. Body parts are gonna be sore at first.

Adjust bike contact points to the rider -riser stem, higher rise handlebars, ergo grips, different saddle... One size does not fit all.

I had a lot of problems with hand numbness before I raised the bars on all my bikes and installed Nitto model 177 handlebars.

https://www.bikeman.com/HB1028.html

The 177(also known as the Noodle) is wide, has a flat ramp, and a slight sweep toward the rider. I have my bars set at saddle height, which keeps me from leaning forward and putting too much weight on my hands. The problem I had with flat bars is that even with bar ends there aren't enough position options. With the Noodle I have FIVE positions to cycle through(flats, ramp, hoods, drops, and hooks). Constantly moving my hands keeps the numbness at bay.

If the bike has a wide, cushy seat, that could be contributing to your numbness problem. I hate to be the inevitable Brooks saddle mentioner, but I've ridden thousands of miles on my Brooks B17 saddles and never even has so much as a saddle sore. They're worth every penny, IMHO.

This.
IMHO you need to first get some decent miles under your belt to adjust your body to a new exertion.
Then you can make more informed decisions about fitting options.

Also, many riders tend to keep their elbows locked which I would think would jar the wrist hand, as well as elbow and shoulder. Make sure your elbows are bent slightly.

I wouldn't assume I needed to raise the handlebars until I had ruled out everything else.

Ok this is a little weird but I thought I'd throw it out there. I'd been having numb hands and none of the normal recommendations helped. The problem disappeared when I wrapped the handlebars with fresh bar tape. Not padded or special in any way, just regular cheap as I could find bar tape. It might have been coincidence, but I don't think so.

My theory is the old tape had gotten worn and mashed around so that I had a pressure point at just the wrong spot, or the grip diameter was too small and pressed a nerve or blood vessel, so a new even wrap alleviated it. It's worth a try.

Numb is better than hurt.

I just went through this myself. In the end I started wearing gloves with padding on the palms and changed my hand position frequently. It's helped a lot, I'm looking at getting ergon grips w/ a bar end so I can change my hand positions more.

Good luck with it and welcome to bike commuting.

I hate to sound like an ergon fanboy, but they really do work. I found out about them while buying a new bike for my wife. She went on a test ride & I borrowed the shop owner's bike to go with her. He had ergons & the pain relief was instantaneous. Ergon has a little flash demo of how their bars ends help with numbness. It makes sense. Definitely worth the $ & a paid goes on every flat bar bike that I get.