Kaye has a bike that’s too big for her to ride comfortably and wanted to know how to choose the right size bike. She’d been told that tire size was the most important factor to consider, but wasn’t sure that sounded right. In this case, heeding her instincts was right. What she needs to know was what size frame to buy.

Hands down, the best way to get a bike that fits is to shop at a reputable bike store. The staff there can discuss types of bikes, help you select the right size, and make sure it’s properly adjusted to you before you leave the store. What if, however, you don’t have a local bike store? Perhaps you can’t afford a new bike, but think you’ve found the perfect used one. While there are many decisions to be made, the final consideration before you pay is ensuring the bike is the right size.

Taking some simple measurements from a bike that fits you comfortably, even if it’s not the one you want, can make all the difference. If the bike you currently own isn’t quite right, try out some others – at a store, from a friend, wherever you can. Once you’ve found a size you like, get out a measuring tape, paper and a pen. To be safe, record measurements in both inches and millimeters. Depending on the manufacturer, their specifications might be in either unit.

First, measure from the middle of the crank spindle (where the bolt is that holds the pedal crank arm on the bike) to the top of the seat post. If you're looking to order a bike, this will be a critical measurement for ensuring the bike is the same height as the one that fit you.

You can also look at standover height (approximately the length of your inseam minus 1-2", or the distance from the floor to the top of the top tube - you should be able to straddle it comfortably with both feet flat on the floor), but unless the bike you're considering has a straight top tube, this won't be much help. You’ll also want more clearance between your crotch and the top tube if you’re riding a mountain bike rather than a road bike.

Check also how far your handlebars are above or below your seat. To calculate this difference, measure from the floor to the top of your seat and from the floor to the top of your handle bars. Subtract one number from the other and you’ll know how far your handlebars are above or below your seat.

Next, you also want to measure the top tube length, the distance from the center of the head tube (where your handle bars are) to the center of the seat post. If this distance is too long for you, you'll end up being uncomfortably stretched out. If it’s too short, you may be riding too upright.

If you can take all of these measurements on a bike that fits, you then want to make sure they're the same on the bike you buy. This should allow you to order a bike with some confidence. That said (and I'll say it again and again), your best bet is always to buy from a reputable local bike shop. They can help you find the right size bike and make sure it's adjusted to fit you.

My beloved bike is a Terry Madeleine. Terry bicycles are designed specifically to fit a woman’s body, especially women who have shorter torsos than your average man (which is many of us). Because Terry sells primarily through their website (www.terrybicycles.com), they have developed a great Terry Bicycle Fit Calculator. It allows you to change the measurements mentioned above (and a couple of others) and see how the configuration of the bike changes. Even if you don’t end up buying a Terry bicycle, it’s worth your time to play with the calculator.

However you choose to purchase your next bicycle, take the time to make sure it fits you properly. Otherwise you might suffer – enough said.