While most bikes are technically sound, improper positioning on the bike can result in a disappointing ride. Proper fitting ensures maximum comfort and a great ride with superior power/wattage. Anything less means riding with sore/numb hands, feet, derriere and inefficient performance. Whether you ride on-road or off, pedal casually or competitively, it's important to pay close attention to how your bicycle fits your body. A properly fitted bike will allow you to ride comfortably and safely, avoid injury, and produce more power, so you go faster with the same or less effort.
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In general, when fitting a bicycle, there are five basic components to consider:
1. Frame size
Simply start by taking your elbow and lean it against the front of your saddle. Your middle finger should be touching the middle of your steer tube exactly. This measurement will determine the precise position of your saddle relative to the stem.
2. Saddle (seat) height
Once your seat to stem distance has been established you can now raise your saddle height. Put your armpit on the saddle and make sure your middle finger is exactly touching the top of the bottom bracket. Femur and forearm proportions have been found not to vary between test subjects therefore this is an extremely accurate measurement technique.
3. Saddle position
4. Saddle tilt
5. Handlebar position
Stem height and length has a direct correlation with the fore and aft saddle position. There is a slight amount of room to play with this measurement however because it has a lot to do with your flexibility. However, it's been found that there's a fundamental connection between torso rotation and finger size.
Frame size is perhaps the most important of all measurements because once you purchase the bike, there are very few—if any—minor adjustments that can affect the overall frame. Frame size is not necessarily dependent on your height; rather, it is more a matter of leg length. Simply, the frame should be easily straddled with both feet flat on the ground, and with perhaps an inch or two of clearance.
• For a road or hybrid bike, you should have an inch or two of clearance between your crotch and the top tube.
• For a mountain bike, clearance should be about four inches—especially if you plan to ride in rugged terrain where an unplanned dismount is likely.
A saddle (seat) set too high or too low can cause pain and lead to injuries of the back and knees, and it will also affect the efficiency of each pedal stroke. As a starting point, set the saddle height so that your knee is slightly bent when the pedal is at its lowest position and the ball of your foot is on the pedal. It is recommended to make adjustments in very small increments and, if applicable, to wear your cycling shoes during the adjustment process.
To check the saddle position, sit on your bicycle—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, your forward knee should be directly over the respective pedal axle (with the ball of your foot on the pedal). For precise measurement, use a plumb-bob to help you visualize the alignment. If adjustments are needed, loosen the seat post and slide the saddle forward or backward, keeping the seat level.
Saddle Tilt and Design
Generally speaking, your saddle should be level. Check this adjustment by using a carpenter's level balanced on the saddle while the bike is on level ground. If your saddle tips too much in either direction, pressure will be placed on your arms, shoulders, and lower back.
Handlebar Position and Distance
Handlebar setup is a matter of personal preference because it will affect shoulder, neck, and back comfort. Generally, handlebars are positioned higher for comfort (a more upright riding position) and lower for improved aerodynamics.
Always Wear a Helmet!
A bicycle crash can happen at any time; however, according to the National Highway Safety Traffic Administration, a properly fitted bicycle helmet reduces the risk of head injury by as much as 85 percent and the risk of brain injury by as much as 88 percent. The following are tips to help ensure the correct helmet fit:
• The helmet should be level on the head, and it must cover the forehead.
• The Y of the side straps should meet just below the ear.
• The chin strap should be snug against the chin so that when you open the mouth very wide, the helmet pulls down a little.
• Put your palm on the front of the helmet, and push up and back. If it moves more than an inch, more fitting is required.
• Shake your head around. If the helmet dislodges, work on the strap adjustments.
• Do not wear a hat under the helmet.
• All helmets sold in bike shops must be approved by the U.S. Consumer Product Safety Commission (CPSC) and should carry a CPSC sticker.