Fitting Your Bicycle
The Basic Ingredient
A comfortable, perfect-fitting bike means your skills will improve immeasurably as you go out and enjoy each ride. And it all starts with the frame. Handlebars, stems and saddles can be swapped out or adjusted to create a better-fitting bike. But getting the frame right is the important first step.
Two Steps to a Good Fitting Frame
Step 1 Get the Frame Height Right
With shoes on, measure from your crotch to the floor. This gives you your inseam length.
Most stores feature a sizing chart for each bike. Start by looking at the stand-over height to determine the frame size that is right for you.
For mountain, touring, and town and trail bikes, stand-over height should be at least 2" shorter than your inseam length; 1" shorter for road bikes.
For example, if you have an inseam of 32", and you're buying a mountain bike, you'll want a stand-over height of about 30".
If the bike has a sloping top tube, as many women's bikes and full suspension mountain bikes do, REI has taken the stand-over height to be measured from a line that is parallel to the floor and bisects the top tube where it joins the head tube. In other words, we pretend the top tube extends horizontally from the front of the bike and measure from there.
Step 2 Get the Frame/Top Tube Length Right
In order to keep your upper body properly positioned while riding, finding the right top tube length is also important. Fortunately, the majority of people will find that selecting a bicycle size using the stand-over height measurement will also provide a frame with an appropriate top tube length. However, keep in mind that just like the saddle height can be adjusted by moving the seatpost up and down in the seat tube, the same is true for the handlebars; they can be adjusted for the amount of reach needed. For those of us with torso and/or arm lengths that are longer or shorter than “average”, or if you would just like to sit a little more upright, simple changes in handlebar height, stem length, and fore/aft saddle adjustments can help fine-tune your bike's fit.
Other Factors to Consider
- Women tend to have long legs and short torsos. For them, the stand-over height is more important than the top-tube length. REI offers women's models that are specially designed with a shorter top tube to accommodate this body type.
- When buying a bike for children, the most important factor is that the bike should not be too large. A large bike can become unwieldy in their hands and lead to a loss of control as well as confidence. REI carries bikes made specifically for kids that come in a variety of frame sizes.
- If you find yourself to be in between two sizes, choose the smaller frame. It is almost always more appropriate to adjust the seat, stem and handlebars to accommodate a slightly larger rider than visa versa.
How do you adjust the seat and handlebars? Read on!
Simple Adjustments, Perfect Fit
Once you have your bike in hand it's time to "dial in" the perfect fit. Dialing-in is a slang term for optimal performance. Handlebars can be swapped, saddles adjusted, gearshifts moved, all to create the very finest biking experience.
Listen to Your Body
There are no indisputable rules for adjusting your bike to fit your body. The formulas serve as a good gauge, but the right fit for you will depend on your body shape and how you like to ride. To get the right bike fit, you have to do 2 things:
- Experiment — As you ride your new bike, try different setups before you decide on one. Ride with your seat slightly forward or your handlebar a little higher, then switch things around.
- Be aware — Pay attention to any aches or pains that develop as you go. For example, a cramped back may be telling you to raise your handlebars slightly, while sore knees may be telling you that your saddle needs adjusting.
"Pedal backward with your heels on the pedals. Your heels should just lose contact with the pedal at the bottom of the stroke. Also, make sure when you do this that you're not rocking your hips."
— Lee Miller, Bike Specialist, REI Seattle store
Check Your Saddle (Seat) Position
Saddle position is largely a matter of personal preference. But, as it affects your body while riding, it's important to find a position that works well.
- Saddle height: Correct saddle height can lower the stress on your knee joints and give you a more powerful pedal stroke. Your saddle should be high enough that your legs almost (but not quite) fully extend at the bottom of each pedal stroke. To check for correct leg extension, rotate your pedals to the 12 o'clock and 6 o'clock positions (while sitting on your saddle). The leg touching the 6 o'clock pedal should bend slightly at the knee when your foot is in its regular pedaling position.
To move your saddle up or down, loosen the binder bolt (or quick-release lever) located at the top of your seat tube — the somewhat vertical frame tube that your seatpost slides into. Slide the seatpost up or down in the seat tube as needed, being careful not to raise it beyond the "minimum insertion mark" etched into its side. Retighten the binder bolt or quick-release lever securely before riding.
- Saddle tilt: There is no such thing as a correct amount of saddle tilt. Some cyclists prefer a forward tilt. Others prefer a backward tilt. Still others like their saddles completely level. To find a tilt position that works for you, take a few test rides and experiment with different setups. To make saddle tilt adjustments, simply loosen the binder bolt at the top of your seatpost (directly underneath your saddle) and make your adjustments. Be sure to retighten the bolt securely before riding.
- Saddle fore/aft position: The fore/aft position of your saddle can have a significant effect on your body position while you ride. To check for correct fore/aft position, sit on your saddle (using a friend or a stationary object to keep yourself balanced) and rotate your pedals until they are horizontal (at the 3 o'clock and 9 o'clock positions). If your saddle is positioned properly, the small bony bump just below your kneecap should line up directly with your forward pedal axle. To check this, simply hang a piece of string with something tied to one end (like a pen) from the bump. The string should hang down directly over the pedal axle. If it doesn't, make adjustments by loosening the seatpost binder bolt and sliding your saddle forward or backward. Be sure to retighten the bolt securely before riding.
Check Your Handlebar Position
To find the handlebar height that works well for you, start with your handlebar stem about 1" lower than the height of your saddle nose. If your lower back starts hurting and you want a more upright body position, raise your handlebars slightly. If you find that you want a lower, more aerodynamic position, lower the handlebars slightly.
On a road bike, switch your hand positions from the handlebars to your brake hoods to the handlebar drops (if you have drop-style bars) from time to time. Find a handlebar height that is comfortable no matter where your hands are positioned.
For a mountain bike, decide which terrain you'll likely ride over 80% of the time. A rider who likes downhill-style riding may want a higher handlebar or "riser" bar, while a cross-country rider will want a lower handlebar for climbing and technical riding.
In both cases, make sure that you can wrap your fingers around your brake levers quickly in case you need to apply maximum braking power fast.
To adjust the height of your handlebars on a road bike:
- Loosen the stem expander bolt located at the top of your handlebar stem (the bolt head should be clearly visible) until it's about 1/4" above the top of the stem. Be careful not to loosen this bolt any further, or the expander nut (hidden inside your stem) may fall into your frame.
- Tap the top of the expander bolt sharply with a rubber mallet (or place a block of wood on top of the bolt and use a regular hammer) to loosen the expander nut inside the stem. This should allow you to rotate the handlebars easily and move the stem up or down (as you hold the front wheel in between your knees). Reposition the stem and handlebars up or down as needed, then retighten the stem expander bolt firmly. Be sure not to raise your stem beyond the minimum insertion mark etched into its side.
If your bike has cantilever brakes, you might have to readjust your front brakes each time you reposition your handlebars. To learn how to perform this adjustment yourself, pick up one of our great at-home bicycle maintenance books.
NOTE: Most mountain bikes come equipped with an AheadSet® system. The stem height on these systems cannot be adjusted. To raise or lower your handlebars, you'll have to choose a new stem or a different set of handlebars or both. AheadSet stems typically come in 90-, 40-, 20-, or 10-degree angles to accommodate various styles of riding.
The space created by your arms and your handlebar is considered your "cockpit" space. You don't want to be too crowded or too stretched out in this space. Saddle adjustments will solve most cockpit space problems but you may also need a wider or narrower handlebar. It's best to let a bike shop handle this adjustment or parts-swap for you.
You should now have a bike that fits comfortably and will provide you with years of enjoyment. There's only one thing left to do — that's right — get out there and ride!
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