Proper Road Bike Fit

The most important consideration when choosing a road bike is proper fit. A $900 bike that fits perfectly will be more efficient (and more fun to ride) than a $3,000 bike that just doesn't feel right.

There's a lot more to fit than simply choosing a particular "frame size" or being able to straddle the bike's top tube.

Proper fit starts with selecting a bike that matches your body's size and proportions. Then, various adjustments fine tune the bike to your particular riding style and flexibility. There's no magic formula that's right for everyone. Your ideal fit may change as you ride more miles and increase your flexibility, or as you get older and less flexible. A skilled bike fitter can be a big help if he's willing to listen to you. But this really isn't rocket science. Most riders should be able set up their own bikes if they understand a few basic principles and are willing to experiment.

Assuming you have a properly-sized bike frame, the most critical adjustments are saddle position (height, fore/aft, and tilt), handlebar height, and stem length. Many comfort issues can be resolved just by raising the handlebars and/or installing a stem with a shorter horizontal extension.

Bikes usually come in several frame sizes, and frame size is always specified by the seat tube length. But choosing a bike strictly by seat tube length is like buying a shirt based only on neck size; it ignores other important measurements. The top tube length and seat tube angle are also important for good fit. For example, if you have short arms or a short torso, you would want a relatively short top tube. Or if your femur (thigh bone) is long for your height, you might benefit from a slack seat tube angle (about 72 degrees). If the frame's geometry matches your proportions, you will feel more comfortable on the bike, and ride more efficiently. You will also achieve the proper weight distribution between the front and rear wheels (ideally 45% front / 55% rear). Frame geometry information is often available from the manufacturer's brochure or website. Be sure to check how the frame dimensions were measured. In the case of seat tube length, manufacturers have at least three ways of making the measurement! That can cause confusion when comparing different bikes. A 56 cm frame from Brand X may be the same size as a 58 cm frame from Brand Y.

A: Seat Tube Length (measured "center to top")
B: Seat Tube Angle
C: Head Tube Length
D: Head Tube Angle
E: Steering Axis
F: Bottom Bracket Height
G: Top Tube Length
H: Chainstay Length

Safety check: When straddling the top tube in your cycling shoes, you should have at least an inch of clearance.

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A good shop will spend the time to help you select an appropriate bike, and will make sure you are fitted properly. Some shops have a "fit cycle" which allows easy adjustment of every possible fit parameter so you can determine your exact requirements. The fit session may be free if you purchase a bike. Make sure the fitter understands your preferences and the type of riding you plan to do. If you feel you're being steered to a particular bike just so the shop can reduce its inventory, look elsewhere. Don't let yourself be talked into a "killer deal" on a bike that doesn't fit you properly. A bike that isn't comfortable is never a good investment. If necessary, have the shop order the correct size bike from the factory, even if it costs a little more.

Shops may use various formulas and "fit systems" to set you up on the bike. These can be good starting points, but proper fit involves more than formulas and body measurements. A 25-year-old racer and 55-year-old recreational rider with identical body measurements may require very different bike setups. The young racer is probably more flexible and will likely want low handlebars and a stretched out "aero" position. The older (or newer) rider will likely be more concerned with comfort. Make sure you're satisfied with the fit before accepting the bike. Take a real test ride (not just around the parking lot) if possible.

Very tall and very short people (and those having unusual proportions) usually have the hardest time finding a bike that fits well. In some cases, a custom frame is the answer. But by careful shopping, most people can find a stock bike that fits well.

Or do it yourself:

Saddle Adjustment

When setting up your bike, first determine the proper saddle height and fore/aft position. Saddle height should be adjusted so that your leg is just slightly bent at the bottom of the pedal stroke. (If your hips rock when you pedal, your seat is too high.) An oft-quoted formula is that the distance from the top of the saddle to the pedal axle (with the crank fully extended) should be 1.09 times your inseam. Another formula (the "Lemond Method") states that the distance from the top of the saddle to the center of the bottom bracket should be 0.883 x inseam length. (Note: Inseam is NOT the same as trouser length. Measure from floor to pubic bone, without shoes, with feet 6-inches apart.) These formulas provide good starting points. But shoe/cleat thickness, foot size, pedaling style, and other factors also come into play. Probably the best approach is to raise the saddle in small increments until your hips just start to rock when you pedal, then lower it a couple of mm.

Beginners often feel more secure with their saddle very low, allowing both feet to touch the ground when stopped and sitting on the saddle. This is much too low. A low saddle doesn't make full use of the leg muscles, and may cause pain in the front part of the knee. If your saddle is too low, try raising it a little at a time until you eventually reach the optimum height.

Proper fore/aft adjustment should place the front of your knee over the pedal spindle when the crank is in the "3 o'clock" position. Riders who do a lot of seated climbing may prefer a position 1 or 2 cm behind the pedal spindle. It's best to have someone make these measurements for you using a plumb line while the bike is on a trainer. (Since saddle height, and fore/aft adjustments interact, remember to check both after adjusting either.)

Make sure your saddle is perfectly level. If it's tilted downward even slightly, your arms will have to work continuously to keep your body from sliding forward. That can be tiring on a long ride.

Handlebar Adjustment

Once the saddle position is set, you can check the position of the handlebars. Racers like to have the bars at least 2 to 3 inches below the top of the saddle to get an aerodynamic position. Recreational riders often set the bars at the same height as the saddle for more comfort. Experiment to see what height you prefer. If the frame is too small, you may have trouble getting the bars high enough for comfort. A tall stem and/or a stem that rises upward can help. Remember to heed the minimum insertion line on quill type stems. On threadless systems, spacers can be moved from above to below the stem to raise the bars (assuming the steerer tube hasn't already been cut too short).

After setting handlebar height, check the horizontal distance from the saddle to the bars. There are formulas and old wives tales about how to do this, but ultimately it comes down to what feels right for you. If you find yourself riding with your arms straight most of the time (no elbow bend), the bars are probably too low or too far forward. When the bars are positioned correctly, you should feel comfortable with your hands on the brake hoods and your arms bent at the elbow. Your torso should be angled forward about 45 degrees, and you should not feel cramped or overly stretched out. Try standing up on the pedals and see if the bar position still feels right.

It's not uncommon for a new bike to come with an overly long stem. Don't be afraid to ask the shop to swap it for a shorter one if you feel too stretched out. DO NOT slide the saddle forward or back to compensate for an incorrect stem length. That will compromise your saddle position relative to the bottom bracket.

Ideally, the stem extension should be about 90 to 120 mm (depending on frame size). If you end up needing a stem outside that range, the top tube may be the wrong size for you. If you're buying a new bike, you may want to consider a different model.

The bottom part of the bars should either be parallel to the ground or angled slightly downward. The brake levers should be positioned so you can operate them easily whether your hands are on the brake hoods or on the drops. Normally, a straightedge placed along the bottom section of the drops should just touch the end of the brake lever. But don't be afraid to experiment with lever position if it doesn't feel right.

Most riders spend a lot of time with their hands on the brake hoods. That's fine, but riding with your hands on the drops is more efficient, particularly when heading into the wind. If your bars are too low, it may not be comfortable to use the drops. Also, some folks with short fingers find it hard to brake or shift from the drops. Switching from "anatomic" to conventional drop bars (if you can find them these days) may help.

General

It's normal to feel a few aches and pains on the first few spring rides. But if pain is persistent or severe, it could be due to improper setup. A stiff neck, sore back, or painful shoulder may be helped by raising the handlebars. As you become more flexible, you may want to gradually lower the bars to achieve better aerodynamics.

If you have an indoor "trainer" that attaches to your bike, you can use it to evaluate your setup. Just make sure the bike is perfectly level. (You may need to put a board under the front wheel.) A half hour on the trainer will often pinpoint fit problems that you wouldn't easily notice on the road.

The information above will get you in the ballpark. Don't be afraid to experiment. It's best to adjust one thing at a time, and do it in small increments (e.g., don't change seat height by more than 1/8 inch at a time). Then take a long ride to evaluate the changes. When you get everything "dialed in," you'll know it!

In summary, small adjustments can make a big difference in comfort and efficiency. Saddle, stem, and handlebar adjustments can often compensate for SLIGHTLY incorrect frame dimensions. But starting with a frame that's perfectly matched to you and your riding style is definitely the way to go.

© Art Harris, 2002