Smart Moves on the Bike

author : AMSSM

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Proper Bicycle Fit and Treatment of Common Cycling-related Medical Problems

Troy Smurawa, M.D.
Member AMSSM
Akron, OH

According to APTA member Erik Moen, PT, CSCS, “Good bike fit promotes good posture with muscles and joints working in harmony. If this doesn’t exist, riders will likely experience pain and be predisposed to injury.” Moen, an elite-level coach through the United States Cycling Federation and director of physical therapy at PRO Sports Club Seattle, says, “The first thing I do, as should any patient complaining of bicycle-related pain, is to bring the bicycle in to check for a proper fit. In most instances, a poor bike fit is at the root of the problem.”

Most cycling experts agree that the most common bike fit errors include incorrect saddle height (high or low), improper handlebar reach (long or short), and misalignments of the pedals and shoes. Cyclists should address shoe set-up, saddle position and handlebar placement to ensure that they have a proper bike fit. Also, cyclists should re-assess their bike fit after bad falls or crashes due to possible movement of cleats, saddle, brake hoods or the handlebars.

Shoe Set-up
When determining proper shoe set-up, cyclists need to factor in that shoes may have different sole thicknesses, pedals may have a different stack heights, and cleats moving fore and aft will affect the relative length of the foot.

Properly sized and fitted shoes should:

• provide support to the arch

• put cleat slots in the proper location relative to the forefoot

If the shoe is too small for the arch length, the cleat will be too far back on the foot.

Proper cleat placement should be located under the second metatarsal head. The second metatarsal is the point of rotation along the transverse axis. This placement provides more efficient biomechanics and delivers greater acceleration of the pedals. It also increases the mechanical advantage by lengthening the effective lever arm. Proper shoes and cleat placement should produce a knee alignment that creates a straight line from the hips through the knees to the second metatarsal head.

Saddle Position
The key goal of saddle position is to maintain good body posture on the bike so as to stabilize both your body and the bike, allow you to breathe comfortably; and generate maximal power output. Proper cycling posture creates a slight forward rotation of the pelvis. This forward rotation will create a neutral spine position, allow activation of core stabilizing muscles, open the abdomen up to facilitate breathing and digestion of food, and improve power output. Posterior tilt limits the abdomen from opening up to allow for deep breathing and digestion, turns off the gluteal muscles resulting in loss of power, and requires flexion of the lumber spine resulting in low back pain.

There are three components to achieving the proper saddle position: height, tilt, and setback.

1. Saddle height should allow for a comfortable extension of the legs without causing the cyclist to over reach the pedals. A saddle set at the proper height should have a 145-155 degree angle at the knee with the leg at maximum extension. Setting the saddle too low increases the pressure on the anterior knee, leading to anterior knee pain as well as limiting maximum power output. Setting the saddle too high increases the strain on the back of the leg, causes hamstring injuries, and forces the cyclist to rock his pelvis back and forth through the pedal stroke.
    

2. Saddle tilt on a well fitted bike with an appropriate saddle will allow the cyclist to position the saddle quite close to level without causing discomfort. The nose of the saddle should not exceed 2.5 degrees in either direction. A forward-tilting saddle will cause the rider to slide forward, placing increased weight on the arms and forcing him to use the handlebars to stabilize. A backward-tilting saddle will cause the rider’s pelvis to rotate posterior, compromising posture and increasing strain on the lower back and pressure on the saddle.
    

3. Saddle setback is the fore and aft positioning of the saddle and is affected by the position of the handlebars and the amount of pelvic rotation and back flexibility. To determine the saddle setback position, the cyclist should place his right foot at the 3 o’clock position and drop a plum line from the tibial plateau (the bony prominence at the front of the knee below the kneecap). This line should bisect the pedal axis. The seat should be moved fore or aft to achieve this position. A setback that is too far forward will put increased pressure on the anterior knee as well as position the rider’s center of gravity too far forward creating an unstable position. A setback that is too far backward increases lumbar flexion strain, causes a loss of power, and decreases the hip-torso angle, cramping the front of the rider’s body.

Handlebar Placement
The location of the handlebars will be determined by a cyclist’s height, strength, coordination and functional goals. The handlebars are positioned so that the cyclist is able to maintain good posture and a good hip-torso angle without over-reaching. The elbows should be slightly bent with the hands resting on the top of the handlebars, on the brake hoods, or in the drops. If using aerobars, the elbows should be directly below the shoulders and bent at 90 degrees. Too long of a reach will put stress on the back and shoulders and cause the rider to slide forward on the saddle. The height of the handlebars depends upon saddle setback, type of bike (road vs. triathlon vs. mountain), cycling distance, flexibility of the hamstrings and lower back, and individual morphology (torso, leg, and arm length). The further back the setback, the higher the handlebars need to be raised to achieve good hip range of motion. The better the hip and back flexibility, the lower a rider can effectively set the handlebars. Cyclists riding shorter distances can tolerate a lower, more aerodynamic position whereas cyclists riding longer distances may need a higher, more comfortable position. Time trialing bikes used in triathlons require a lower, more aerodynamic position whereas mountain and recreational bikes with a higher position will have better stability and allow more control of the bike.

Troubleshooting Common Bicycling Pains

Neck and Back pain
Cycling-related neck and back pain is usually due to muscle strain. Anything that forces the rider to increase stretching of the neck or back forward may cause pain. Hill climbing and big-gear pushing results in back pain, as riders tighten their back muscles to produce more power. Other important factors that can contribute to neck and back pain are handlebar position, saddle position, body position, top tube length, flexibility, and riding distance.

Hand numbness or pain
Cyclist’s palsy is caused by compression of a nerve in the hand causing pain, tingling and numbness along the course of the nerve. Compression in the heel of the hand (below the little finger) affects the ulnar nerve and presents with symptoms in the little and ring fingers, whereas compression at the wrist affects the median nerve and presents with symptoms in the thumb, index, middle and ring fingers. Symptoms are worse while riding and may last several hours afterwards. Although this problem usually improves after riding stops, if it is ignored, it can lead to permanent nerve injury.

Knee pain
Overuse knee problems are due to the repetitive and constant nature of riding over time, and are one of the most frequent reasons cyclists seek medical attention. Knee complaints can be identified as either anterior, medial, lateral or posterior of the knee. Even without knowing the specific diagnosis, by identifying where the knee hurts, it is possible to make bike position adjustments.
 

Iliotibial Band Syndrome
The iliotibial band is a fibrous band of tissue that runs along the lateral aspect of the knee. The band becomes inflamed and painful either at its insertion into the lateral aspect of the tibia or as it rubs over the lateral aspect of the femur. It is typically caused by excessive stretch on the band from too much pull on the lateral knee.

 

Foot numbness or pain
Pain, burning and numbness in the feet or the toes is usually caused by pressure around the foot. Rarely, it could be a result of nerve compression from the back or thighs causing sciatica. Shoe fit and cleat position typically contribute to the problem.

 

Saddle soreness and discomfort
Sores of the buttocks and groin area commonly occur in cyclists. Saddle sores are often related to the type of saddle, saddle position, clothing, and riding a cyclist experiences. Infection, pressure and friction are the three main factors causing saddle sores. Bacteria entering blocked sweat glands or hair follicles can lead to an infection. Increased saddle pressure from poor saddle position, lack of padding, or prolonged riding leads to a breakdown of the skin. Increased pressure between the pelvic bones and saddle compresses the nerves and arteries and can cause numbness. Chafing occurs on the inside of the thighs from repeated rubbing during the up-and-down motion of the pedal stroke. Sores occurring repeatedly on the same side may be related to the leg on that side being shorter. Using a firm bike saddle with proper positioning and wearing clean, dry, padded cycling shorts is the best way to avoid developing saddles sores.

Equally important to proper bike fit is a rider’s physical condition. “Good flexibility of the hamstrings, quadriceps, and gluteal muscles is crucial because these muscles generate the majority of the pedaling force.” observes Moen. He adds, “Proper stretching, balance and flexibility exercises help with coordination of cycling related skills such as braking and cornering.” Improving strength, flexibility and fitness will help a cyclist achieve a more comfortable, efficient and powerful riding position.

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date: July 17, 2005