Frame & bits sizing for new rider

Folks, hello from Indiana. Short-time rider, first-time poster. I currently ride a 1999 Schwinn Frontier MTB that I purchased new. It's cheap, heavy, and difficult to get down the roadway. I'm interested in buying a road bike that I can take some distance and get into more serious riding, not racing or competitive just yet, but more on the 50mi a weekend type rides across Indiana.

First question: How do I determine what dimensions I need for frame, crankset, etc? I've seen a few posts that mention a calculator but I haven't found it.

Many on-line retailers have the calculators you are looking for ... e.g., COLORADO CYCLIST, etc.

Links to bike fitting calculators, technology, and bike fitting systems. The FitStik.

Fit Calculator - Competitive Cyclist

Competitive Cyclist Fit Calculator - How to Measure | Cycling at YourCycling.com

The Colorado Cyclist :: Bicycle Parts and Accessories

Input the data into several to see if there is a difference ... these fit calculators should only be looked upon as a starting point & the frame size you ultimately end up with may be different.

As far as your Schwinn, different tires & tubes (i.e., "city slicks") may make a signficant difference.

Be certain that all of the 'moving parts' move freely ... fresh grease for the bearings can do wonders.

The proper crank length for a given rider is open to debate, and formulas exist based on seemingly random biases which do not appear to take into account all dimensions AND RIDING STYLE of a given person for whom the crank is intended.