In the words of Andy Pruitt:
“Bike fit is a marriage between bike and rider”
“Make the bike fit your body;don’t make your body fit the bike.”
If you plan to participate in this months Bike to Work Week, are a bike commuter or a competitive cyclist, proper bike fitting is crucial. While cycling is generally easy on the body, in comparison to heavy impact activities, things can go wrong resulting in more than minor aches and pains. Poor bike fit, over-training, poorly designed training programs, cycling accidents and aging can all lead to injury.
While somethings, like crashes and aging, are out of your control, let’s take control of what you can! Here are some key points that should be taken in to consideration while fitting your bike to ensure proper form and prevent common injuries.
There are many ways in which a bicycle can be adjusted to fit your body and very few ways in which your body can contort to a bike. This is the moment where you remove that image of a perfect cyclist from your head and realize that we are all built differently. Someone with long legs and a short torso will not have the same fit and position on a bike as someone with short legs and a long torso. It’s not a matter of how you look on your bike its a matter of how to promote power output and avoid injury.
First, fitting factors including: saddle position, frame size, saddle setback and saddle tilt need to be addressed before considering handlebar position, pedals/cleats and foot position.
Refer to this image to answer some of your questions regarding bicycle jargon as we discuss fitting:
Bike Saddle Position:
This is the most important factor to get right! A saddle that is too low can result in patellar tracking disorders causing pain in the front of your knee. A saddle that is too high can compromise the amount of power you output and also result in extra stretching of the hamstrings resulting in pain located behind your knee.
- Road Bikes: The easiest way to approximate the saddle position on your road bike it to first clip in and ride for 5 minutes at a medium gear to loosen the muscles to ensure accuracy. Once the muscles are warm, unclip and place your both heels on the pedals, be sure you are seated as you would be while riding. With your heels on the pedals, as you pedal slowly your leg should reach full extension at the bottom of each stroke. As your heels go around the bottom they should just barely loose contact with the pedal. Your pelvis should be able to remain level with no hip rocking. If you have been able to do this with no problem your saddle is at the correct height, when you clip in the ball of your foot will be over the axles of the pedals allowing for the length of your feet to add to the length of your legs. This will result in the proper amount of knee bend at the end of each stroke.
- Mountain Bike: While the same fitting techniques can be used as for road bikes, one must consider the fact that most mountain bike crankarms are longer than those on road bikes. The saddle should be lowered the equivalent in length difference to combat the change.
Bike Frame Size:
The appropriate bike frame size can be determined using LeMond’s crotch to floor measurement. This is done by measuring in cm the distance from your crotch to the floor (your inseam measurement to the floor), then multiple by 0.65. For example, my inseam to the floor is 31 inches converted to 79 centimeters.
79 x 0.65 = 51.35 cm
This indicates that I should be riding a frame that measures from 51 to 52 cm, measured along the seat tube.
For those who need their handlebars high compared to their saddle may want to multiply by 0.70 to determine proper frame size.
79 x 0.70 = 55.3 cm
Bike Saddle Setback:
How far or close your saddle is in relation to the handlebars is dependent upon the length of your thighbone (femur). This is important in ensuring that your knee is in the proper position to drive the most power through the pedals. As well as, ensuring your hips aren’t too far forward or too far back, preventing the risk of injury and chronic pain.
The objective is to have the knee directly over the ball of the foot at the point of maximum power.
A plumb line can be used to ensure proper positioning. Drop the plumb line from the point of the knee, it should touch the end of the crank arm (which should be in the horizontal position). If the line falls ahead or behind this point, the saddle should be adjusted forward or backwards, until the line is right. After the line has been set for one leg, repeat for the other. If the plumb line doesn’t match there is a difference in femur length between legs, the difference will have to be split in the setback.
As the saddle setback is adjusted a considerable amount the saddle height may need to be re-checked.
Bike Saddle Tilt:
Your saddle should be level with the ground, if you have yours tilted up or down, your bike does not fit. Having your saddle tipped down places extra strain on your hands, wrists, arms and shoulders and can result in fatigue, pain or numbness. Having the saddle point up can result in low back pain problems along with saddle sores and numbness. There is an exception, those with unusual pelvic tilts or increased lumbar curvature may benefit from an upward tilt.
Now that the primary fitting factors have been addressed we can move on to handlebar position, pedals/cleats and foot position.
Reach determines the angle of your torso in relation to the ground. This is one of the most individual parts of bike fitting. Many factors come in to play when deciding handlebar height, including: low back and hamstring flexibility, low-back strength, arm and torso length, posture, and shoulder strength.
- An old italian wives’ tail says to determine reach, put your elbow against the tip of the saddle and extend your open hand towards the handlebar. The end of the middle finger should come within an inch or so of the bar.
- For the relationship of handlebar height to saddle height, measure your fist across the knuckles from the little finger to index finger. Then use a stem height that makes the distance between the bar top and saddle top equal to your fist measurement.
- After you have placed your handlebars take a couple rides and listen to your body, adjust based on the feedback. Be aware of the feeling in your arms and any numbness in your hands or fingers, if any symptoms are noticed your fit needs to be adjusted.
- A flat bar is more commonly used among commuters, who swap out their drop bars, or mountain bikers. This allows riders to sit more upright, useful in instances where you may stop at traffic signals.
- The reach for you flat bar should be the equivalent of the reach from the drop bar brake hoods to the saddle on your road bike.
Handlebar Width is typically the width of your shoulders but can be found in many different sizes. For more comfort a wider grip can be suggested.
Pedals & Cleats
Clipless pedals have made major improvements in cycling including preventing the pressure of toe straps and making for an easy exit in crash situations. However, what clipless pedals do not allow for is compensation for unequal leg lengths. With cleats if one leg was longer than the other, the short legs cleat would rise slightly and with straps you could find some give allowing for compensation. Now with clipless pedals it is important to address leg inequality with proper inserts as needed to prevent cases of low back pain.
“Neutral” position should be practiced while performing cycling activities. In general, the ball of your foot should be over the center of the pedal axle. This theory works best for a men’s size 9 foot, if you find yourself in the spectrum of larger feet you may want to consider moving the clip posterior towards the heal, resulting in increased stability. For those who have shorter feet you may want to move your clip up and ride more on your toes, this allows for more leverage.
Bike to Work Day 2016! Visit our pitstop on the W&OD trail at Little Falls Street on May 20th from 6:30-9:00am for light refreshments and giveaways!
If you have any questions regarding finding your ideal riding position or common cycling injuries feel free to reach out to Dr. Reilly at firstname.lastname@example.org or call for an appointment today (703)-760-8110!