I recently purchased a Schwinn Trailway men's bike. I'm 6'1", 225 pounds. I'm having difficulty with the narrow 21" handlebar. Are there extensions available to widen them, do I simply replace the handlebar?
Thanks!

Just get new handlebars (and avoid nasty dental bills).

They measure in millimeters. The two numbers you want to watch for are clamp diameter (31.8 and 25.4, which looks like yours unless you replace your stem) and the width (up to you, but there are bars more than 800mm [31in] wide).

A good way to find the correct bar width is do a few push ups and measure from pinky to pinky on the floor. This is because your hands will naturally go out to most supportive or strongest position. Buy a bar at, or just wider, than that. Buying or using a bar that is too wide is bad too--you will then lean too far forward and your hands and arms will support too much weight and get fatigued--your shoulders and low back might start hurting too. FYI, you can carefully cut down a wide bar to a narrower width with a hacksaw or a pipe cutter.

The pipe cutter works great, but it will leave a burr in the inside and outside. You will need to file these down to install grips (outside) or accessories like mirrors (inside). A little oil on the cutting wheel will help make the cut easier. If you decide on a hacksaw I would suggest using one or two hose clamps as guides to ensure a straight cut.

Thanks guys, that's good info!

From what I can seen on the Schwinn website, athrowawaynic is correct that it is a 25.4mm clamp diameter. Handlebars with a 630mm width are most common and easiest to find. Check to see if there is a bicycle co-op in your area that should have plenty of used ones.

Swapping out the bars is relatively simple. You have to remove the grips which are just slipped onto the bars. Use a thin screwdriver or 2.5mm allen wrench under the grips and spray in water, Windex or alcohol (but don't use an oil based lubricant). Pull out the screwdriver and the grips will be lubricated enough to twist off. The shifters/brake levers are secured with a bolt of some kind. Since they are single unit, there should only be one. Slide them off. Loosen and remove the two bolts on the stem (in the middle of the bar) and the handlebar will come right off.

The replacement is just the opposite of what you did to take it off. Snug the stem bolts down so that the handle bar doesn't twist and tighten the brake levers enough so that they don't move. You don't need to be a total gorilla about it but make sure the bar doesn't twist before you ride.

If you have some hairspray, spray it inside the grips and slide them back in place. This will keep them from turning. If you don't have hairspray, rubbing alcohol (or even drinking alcohol) will work but it takes longer to dry.

It sounds more complicated than it is. Good luck

I would suggest that you only tighten the shift/brake lever clamps so that they do not move with use but will move with firm force. This is called "race tight" and is done to minimize the chance of injury in a crash.