Mountain Bike vs Hybrid
 

I've got an older Schwinn mountain bike (back when Schwinn was a good bike!). Currently, I'm running some multi-purpose tires (pavement and dirt road riding). I also have an older Bianchi Strada road bike too.
I am more comfortable with upright riding position of the mountain bike vs my road bike. Been thinking about buying a hybrid.
But just curious, what would be the advantage of buying a hybrid vs just putting different tires on my mountain bike, such as a good 26x 1 1/8" high pressure tire?
I live in the hilly Arkansas Ozarks, so low gearing is a must for me.

There really won't be much difference at all. There are lots of flavors of hybrid, sure, but they're either road bikes with flat bars and slightly thicker tires, or mountain bikes with skinny tires.

For example, right now I've got a Cannondale Bad Boy (already a MTB with skinny tires) and a Rush (full suspension MTB). For kicks, I put the Bad Boy's 700x28 wheels on the Rush and flipped both shocks to lockout mode. Apart from being a little heavier, the Rush, with those skinny slicks, rode nearly identical to the Bad Boy.

If your Schwinn has a suspension fork, you'll gain some efficiency by going with a rigid fork, whether you get just a fork (it would need to be suspension-corrected) or a new bike.

No suspension fork on my bike.
Might be good training for my longer rides, to do shorter runs on the big tires, then swap out to smaller ones before doing longer rides.
Most hybrids I've looked at have 700cm tires, vs 26" on my mountain bike. Not sure how important that is.

Hutchinson Python tires improved the speed of my mountain bike, however since I do 95% of my riding on pavement I decided to buy a Kona PhD last year. Neither bike is as fast as my road bike but the riding position relieves discomfort on my bad back over longer rides. With the Kona I average 2 MPH faster than my MB expending far less effort so over the course of a 50+ mile ride the difference is very apparent. No supension components on a lighter weight bike with skinny tires makes a significant difference.

Have been looking at a Trek 7700, but don't want to spend that kind of money, if I won't see much of a difference.
I was never too convinced about getting a much lighter bike, since I did weigh well over 200 lbs. I've lost 40 this year, now down to 204 (and still loosing). Thought it would make more since to loose 10 or 20 pounds of body weight, than to pay big bucks for lighter bike. In other words, fat boy on light bike didn't seem to make much sense.

2 cents from a novice...ignoring weight (any bike under 30 pounds, with aluminum-alloy rims, is light enough for me) if you can get your bike adjusted where your butt, hands, and feet are where you want them then it should be a comfortable ride. You can put slick-tires on for efficiency/speed on pavement. I will add that it is nice to have acceptable shifting. If your into speed (like going 30 mph+ down hills) you might run out of "gear" on a mountain bike (I don't know how any "official" hybrids are geared).

I would put smoother tires on your Schwinn. I'm getting a set of these Conti's for my older Trek. I don't think buying a hybrid would make much of a difference.

http://www.rei.com/product/711641

http://media.rei.com/media/711641_321Lrg.jpg

Narrower tires on the Schwinn is the way to go, but the current rims may be too wide for tires 28 mm wide. See the table near the bottom of this page http://www.sheldonbrown.com/tire-sizing.html New wheels would still be cheaper than a decent hybrid.

Before you go any further, Schwinn used a different 26" tire/wheel on their early mountain bikes. Schwinn used what is now called 650B back in the early 80s with a bead seat of 584mm. The bead seat diameter will be printed on the tire in parenthesis next to the 26" x 1 3/8". Newer 26" MTB tires are a bead seat of 559mm and the size is graded in a decimal, not a fraction.

Sheldon Brown's tire sizing guide will explain this more visually then my post. Different sized wheels may be hard to install, as the brake bosses are welded to match the factory installed wheels.

I bought my mountain bike new from a bike shop in the early 90's, so it's less than 20 years old.

Current tires (Bontrager Earl) say 26" x 2.125 (50/52) To Fit HB 575 Rim"

Thanks for the info- just 1 month too late. I bought a Schwinn Mirada for $25.00 off CL. Just needed tires. I had a set of new 26" city tires- $15.00 for 2. No way were they going to stretch to fit. 650B tires are about $45.00 a set including delivery. Choice is limited.

That being said, the Schwinn is a decent around town bike. Rigid MTB's make for good city bikes I like the ability to launch off curbs & go over obstacles, taking the odd stairway down if necessity demands.

I am riding my 10 year old Giant Innova hybrid and it has 700c tires - they are not slicks, but they are not knobby either - good deep tread pattern. I had a mtb prior to getting this one. I loved my mtb but it was never fitted to me and was way too short and I developed knee issues riding it. My hybrid was a good choice because not only am I an overweight rider, but I also need the upright riding position. The thing I really like about my hybrid versus my previous mtb is that I can ride on pavement and get up some decent speed but there have been times that I needed to run off trail and it can handle it fine. Alot depends on your tires too. But my hybrid, even with full panniers and gear is still lighter than my mtb. I recently got it outfitted with bar ends which make a huge difference in hand positions, a new gel/foam cutout saddle and got it fitted to me. I love riding that bike! I have read that you can switch out to slicks which make a difference in speed, so I would suggest trying that like one of the previous posters on this thread. When I recently got back into biking I could only do a few miles at about 8.5 mph (I had to have heart stents put in last year) but now I am doing approx. 60 miles a week and averaging between 12.5 and 14.5 mph with faster sprints of 18 mph and I have lost over 55 lbs. I am getting stronger and feeling great, so I applaud your weight loss and getting fit efforts. Keep up the good work!! Here is a pic of my bike.