For most riders, the first step in getting the right size bike is to stand over the frame with both feet flat on the ground. A properly-sized road bike frame will give an inch or two clearance between the top tube of the frame and your crotch. Not too much, not too little. A mountain bike should have more space - maybe the width of your hand across your fingers.
On women's bikes that don't have the high top tube going between the seat and the handlebars, you can skip this step.
Notice on how this rider's leg is almost fully extended at the bottom of his stroke, with just a slight bend to the knee. You want your seat set to the height that allows your leg the same extension.
You want to have the bicycle seat set to a height that allows your leg to extend until it is almost completely straight when you are sitting on the seat. There should be only a slight bend to the knee when your foot is on the pedal in the bottom position. This will maximize power and minimize fatigue.
A common mistake is for people to think that they should be able to sit on their seat and still plant their feet firmly on the ground. Riders should come off their saddles and straddle the bar when stopping the bike. If you can sit on the seat and touch your feet to the ground other than on tippy-toes, your seat is too low.
For maximum comfort and pedaling effeciency, you want your seat to be pretty much level, so that you can sit on it and pedal without having to consciously monitor where you are on the seat. Too much forward tilt, and you'll feel like you're sliding forward. Too much backward angle, and you won't be able to get any power and you'll have the sensation that you're slipping off the back. Both of these situations are distracting and uncomfortable.
When on a bike seat, your weight should be borne by the same spots on your rear that you feel underneath you when you sit upright on a hard firm surface. In addition to adjusting the tilt angle, you can also move the seat forward and backward in relation to the seat post. This will help make sure you're comfortably centering your weight in the right places.
Proper Handlebar Adjustment
The goal of handlebar height adjustment is to find the position where you can ride comfortably without putting strain on your back, shoulders or wrists. There is a lot of personal preference here, and a fair amount of variation between body types, so don't be afraid to experiment until you find the setting that is best for you. And remember, the staff at your local bike shop are always happy to offer advice on finding the proper fit.
Generally, the following guides may be used for different types of bikes:
- Road bike: on a road bike, the top of the bike's handlebars should be a bit lower than the top of the saddle, in the range of an inch or two. This allows for a definite forwarding-leaning, more aerodynamic ride.
- Mountain bike: on a mountain bike, the handlebars will often be set even lower, perhaps three to four inches below the saddle. The point in this is to provide a low center of gravity, particularly if you're going to be riding off the pavement. so as to give a lower center of gravity. Also, mountain bike riders often come out of the saddle to negotiate bumps, logs and other obstacles, and the lower handlebars provide a better, more balanced position in distributing the rider's body weight across both wheels.
- Hybrids and Cruisers: With these bikes, where you're sitting much more upright (in contrast to road and mountain bikes) the handlebars will be raised correspondingly higher, approximately an inch or two (or more) higher than the seat. This means much more of your body weight will be borne by your rear, instead of your shoulders, wrists and arms.
Remember, when setting the height of your handlebars, personal preference and variations in physique will have an important effect. You should feel free to make adjustments until you find the position that allows you to ride comfortably for extended periods of time. In general, the higher the handlebar is set, the more upright you will sit.
NOTE: All handlebars have a minimum insertion mark. Make sure you don't raise your handlebars into a fixed position so high that you pull this mark up out of the frame. Below this point, it means that there is less than two inches of the handlebar stem remaining inside the frame, and the handlebars are susceptible to breaking which will cause a mean crash.