Cycling comfort and efficiency begin with a bicycle that fits right. This article, which includes video advice from REI Outdoor School instructors, explains the basics of bike fitting.

Road Bikes

The checklist for evaluating the fit of a road bike also applies to many urban, touring and commuting bikes. Note, however, that the aerodynamic riding position of road biking is not necessarily the most comfortable for extended bike touring or for heavily loaded bikes.



As our video shows:

Check the frame's standover height. This ensures your chosen model is correctly sized for your leg length and flexibility. (See diagram below.)

  • If you are at an REI store, select a bike, throw a leg over its top tube and straddle the tube.
  • Customarily you want about 1" of clearance between your body and the top tube (if, that is, the bike is equipped with a traditional straight top tube, one that is parallel to the ground). When you lift the bike you should have approximately 1" of clearance between the ground and tire.
    • The recommended amount of clearance is the same for men and women.
    • Wear your cycling shoes when evaluating standover height, since the thickness of the soles will contribute to your overall leg length.

Stand-over height
                             Stand-over height

  • If the bike is equipped with a slightly sloping top tube (known as a semi-compact design) or a top tube with a more pronounced slope (a compact design), expect to have clearance of 2" or more.
  • Later in this article we provide guidance for gauging this measurement outside of a store.

Adjust seat (saddle) height.

  • Ask a friend to hold the bike upright while you hop on the saddle.
  • Ideally, at the bottom of a pedal stroke you want to feel a slight bend in your knee. Aim to come within 80% or 90% of full leg extension.
  • Use a wrench (or the quick-release lever, if equipped) to secure the seat at the ideal height. Note: If you are working with a carbon-fiber frame and/or seatpost, use a torque wrench to set the height to the manufacturer's specification, or have a mechanic at an REI bike shop tighten this properly.

Adjust seat position. Your knee should be aligned over your forefoot for greatest efficiency.

  • In addition to moving up and down, the seat can be moved forward or backward.
  • Again, ask a friend to support the bike while you examine your body's position in the saddle.
  • When in the correct position, a plumb line dropped from the bottom of your kneecap would lead to the ball of your foot. This means most riders will pedal with their shins angled just slightly forward.
  • For most riders, the saddle should be parallel to the ground.
  • Choose the right stem. This is to comfortably position your arms and torso.

Check the stem. Your stem length and angle determine how far you reach and bend at the waist to reach the handlebars. If you need to increase or decrease the stem length for a comfortable reach to the bars, you will most likely need to have a bike shop change out the stem to one that is the correct length and angle. A few road-bike stems have adjustable angles that allow you to raise the handlebars by changing the stem angle.

To gauge the fit of your stem:

  • Ask a friend to support the bike while you're on the saddle.
  • If you must extend and lock your arms to reach the handlebar, the stem is too long. Road vibrations will pulsate through locked arms into your neck and back, causing aches and fatigue.
  • The goal: A riding position that results for a modest amount of shock-absorbing bend in your arms without forcing you to reach too far to apply the brakes. Tip: If it feels as though you could comfortably play piano keys on your handlebar, your arms are in a good position.
  • This should place your back at a 45° angle, which puts your head in a comfortably forward-tilted position and keeps shifters and brake levers within easy reach.
  • Note: Racers prefer more radical, aerodynamic body and arm positions to maximize speed.

Mountain Bikes

First, check the frame's standover height.

  • As with a road bike, if you are at an REI store and can physically examine several bikes, choose a model, throw a leg over its top tube and straddle the tube.
  • With shoes on, when you lift the bike you want 2" (minimum) clearance between the tire and the ground.
    • The recommended amount of clearance is the same for men and women.
    • If your bike has full suspension, you'll want less initial standover clearance (1"-2") because the bike sits higher than when you are actually sitting on the bike, which compresses the suspension.
  • It is not unusual for aggressive riders to seek out 3" to 5" of clearance.
  • Later in this article we offer tips for determining this measurement if you cannot visit a store.

Check the distance from the seat to the handlebar.

  • The preferred position will allow you to ride comfortably with just a slight bend in your elbows as you grip the handlebar.
  • The modest flex in your arm makes it easier to absorb any jolts caused by obstacles along your route.

Check the seat (saddle) height.

  • When fitted correctly, your legs should bend just slightly at the bottom of a pedal stroke.
  • If your feet can simultaneously touch the ground while in the seat, that's an indication your seat is too low.
  • In general, bicycles designed for dirt jumping, freeriding or downhill mountain biking do not need seat-height adjustments.

Adjust seat position. Your knee should be aligned over your forefoot to pedal most efficiently. This step is not discussed in our video in fitting a mountain bike, but this guidance (also described in our road-bike section) is valuable advice that should be followed.

  • In addition to moving up and down, the seat can be moved forward or backward.
  • Again, ask a friend to support the bike while you examine your body's position in the saddle.
  • When in the correct position, a plumb line dropped from the bottom of your kneecap would lead to the ball of your foot. This means most riders will pedal with their shins angled just slightly forward.
  • For most riders, the saddle should be parallel to the ground.

Check the stem. This is to comfortably position your arms and torso. (As with point 4, this advice is visually demonstrated only in our road-bike video, but it is true for mountain bikes as well, so we repeat it here.)

Your stem length and angle will determine how far you reach and bend at the waist to reach the handlebars. Some stems have adjustable angles that allow you to raise the handlebars by changing the stem angle. However, if your stem is not adjustable or you need to increase or decrease the stem length for a comfortable reach to the bars, you will need to have your bike shop change the stem to one that offers the correct length and angle.

To gauge the fit of your stem:

  • Ask a friend to support the bike while you're on the saddle.
  • If you must extend and lock your arms to reach the handlebar, the stem is too long. Trail vibrations will pulsate through locked arms into your neck and back, causing aches and fatigue.
  • The goal: A riding position that results for a modest amount of shock-absorbing bend in your arms without forcing you to reach too far to apply the brakes. Tip: If it feels as though you could comfortably play piano keys on your handlebar, your arms are in a good position.
  • This should place your back at a 45° angle, which puts your head in a comfortably forward-tilted position and keeps shifters and brake levers within easy reach.
  • Note: Racers prefer more radical, aerodynamic body and arm positions to maximize speed.

Comfort/Recreational Bikes

A note about standover height.

  • This is usually not a concern. Comfort bikes are often equipped with steeply sloping top tubes with clearance of 5" or more.
  • Some bikes in this category are designed to allow the rider to put their feet flat on the ground when seated.

Adjust the seat (saddle) height.

  • Position the seat so you can enjoy a comfortable, almost fully upright sitting position while accommodating a slight bend in your elbows as you grip the handlebar.
  • As with all other bikes, the seat should be positioned so your legs never fully straighten during a downstroke. A little flex in your knee at the bottom of your pedaling motion is desirable.
  • Most comfort bikes come with adjustable stem angles that allow you to raise or lower the handlebars. See the stem-adjustment instructions given above in the road and mountain bike sections.

Kids' Bikes

Check the standover height.

  • Whatever top-tube style is employed, seek out 2" to 4" of clearance.

Adjust the seat height.

  • Position the seat so your child can enjoy a comfortable, almost fully upright sitting position while accommodating a slight bend in their elbows as he or she grips the handlebar.
  • Kids' bikes or adult bikes, the objective is the same: The seat should be positioned so legs never fully straighten during a downstroke. It's good to have a little flex in the knee at the bottom of your pedaling motion.

Talk to a Bike Fit Expert

Whatever style of bike appeals to you, ideally you can visit an REI store and consult with one of our bike mechanics to help you sort through the fit issues involved with a bike selection.

Online Bike Fitting

Happily, choosing the correct frame size can be achieved without a visit to a store.

REI includes a sizing chart with each bike we feature online. The chart includes the standover height for each frame size of that particular bike. The distance between your inseam and the standover height should fall within the ranges discussed in the sections above.

For example, if you have an inseam of 30", and you're buying a mountain, urban/commuting or touring bike, you will want a standover height between 25" and 28", depending on how aggressively you ride. For a road bike, your preferred standover height would be 28" or 29". For a comfort bike, the right standover height would be in the vicinity of 27" or 28".

To measure your inseam:

  • Locate a large-format book (the coffee-table variety), tape measure and pencil.
  • Stand against a wall, with shoes on.
  • Wedge the book between your legs, with the book's spine parallel to the floor while against your crotch.
  • With the pencil, lightly mark on the wall where the book's spine meets the wall (at your crotch).
  • Measure from the mark to the floor. This is your inseam measurement.

Sizing Kids' Bikes

Children, especially girls, tend to have long legs and short torsos. When buying a bike for children, the most important factor is that the bike should not be too large. Do not choose an exaggerated standover height hoping your child will "grow into it." A too-large bike can become unwieldy in a child's hands and lead to a loss of control as well as confidence.

Other Adjustments

Saddles, handlebar tilt, some stem angles, flat bar shifters and brake levers can all be adjusted to create a more comfortable fit. To understand where you need to fine-tune your ride, do 2 things first:

  • Experiment: As you ride your new bike, try different setups before you decide on one. Ride with your handlebar or seat a little higher but make small adjustments; ride the new setup long enough to allow your body to adjust to it.
  • Take mental notes: 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.

After getting acquainted with a new bike, REI encourages riders to make a return visit to a store for follow-up consultation on fit-related topics with a bike mechanic.

The following general guidance provides some self-evaluation/self-service suggestions.

Seat Position

Saddle position should align the knee over the forefoot/pedal spindle. Resist any inclination to adjust your saddle to achieve the proper reach to the handlebars.

Seatpost binder bolt
                            Seatpost binder bolt

Seat height: When extended in a downstroke position, does each leg retain enough bend so that it falls just short of being fully straight? If so, your seat is properly positioned.

To move your saddle up or down, loosen the seatpost binder bolt (or quick-release lever, if equipped) located at the top of your seat tube. 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 before riding.

Seat tilt: REI recommends starting with the saddle parallel to the ground to get a rider acquainted with this traditional setup. Some cyclists in time may prefer a forward tilt. Others might want a backward tilt. Yet a no-tilt alignment is often the best approach. To find a tilt position that suits you, experiment with different setups. To make saddle tilt adjustments, simply loosen the saddle binder bolt (or bolts) at the top of your seatpost (directly underneath your saddle) and adjust as needed. (Note: The saddle binder bolt (or bolts) is different from the seatpost binder bolt.) Retighten the saddle bolt(s) before riding.

  • Note: As mentioned earlier in this article, if you are working with a carbon-fiber frame and/or seatpost, use a torque wrench to properly secure the height to the manufacturer's specification, or have a mechanic at an REI bike shop take care of this.

Seat fore/aft position: In the ideal pedaling position on any style of bike, riders will pedal with their shins angled forward just slightly. A line could be drawn from the bottom of your kneecap to the ball of your foot. If your shin is too vertical, that line would be pointing at your heel. (Review our road-bike fit video for a demonstration.) To achieve the correct shin tilt, loosen the seatpost binder bolt and slide the saddle forward or backward as needed.

Seat style: Saddle technology has flourished in recent years. A wide variety of saddle widths and styles can be purchased your individual fit and comfort preferences.

Handlebar Position

Most bikes are now equipped with fixed-positioned stems. To adjust the position of your handlebar, you may have to choose a new stem, a different handlebar or both. Step risers and other components allow stem heights, angles and lengths (plus handlebar height and width) to be modified.