Unless it is related to lung capacity or muscle fatigue, pain while cycling or biking is not normal, says Izette Swan, co-founder and owner of Real Rehab Sports + Physical Therapy in Seattle.

So, when cyclists complain of lower back or knee pain, or numbness or tingling in their hands, feet or butt, the culprit is often an ill-fitting bike.

“Once the body and the bike are in alignment and the pain is removed from equation, clients often see improved performance in meeting their goals (such as finishing a race), taking their competition to next level, or just more enjoyment in doing something they love,” said Swan.

This, of course, is the goal of a biomechanical bike fitting performed by a physical therapist. Not all bodies are shaped and work alike, Swan says, so it’s unreasonable to expect an off-the-shelf bike to immediately fit a person’s build and riding style, making it necessary to match the bicycle to one’s body through modifications and adjustments.

For Swan, this starts with watching a person’s body movements off the bike.

As a physical therapist, Swan considers the cyclist’s range of motion, leg and core strength, and movement patterns when walking, squatting or stretching. It helps the therapist understand what parts of the body are stronger and move more efficiently than others and where the deficits are, which may explain why the body is out of step with the bike.

Next, Swan analyzes the cyclist’s posture on the bike. What is the knee angle when peddling? How is weight distributed between the feet, saddle and hands? Is the pelvis stable on the saddle? Any combinations of mismatches between the body and how the bike is configured can cause discomfort, pain and eventual injury, Swan said.

For example, one of the most common complaints is knee pain, said Swan, for which she considers several possible causes.

“Are they peddling vertically, which means the leg and foot are moving from 12 to 6 and 6 to 12 on balanced feet and in even strokes?” she said, making references to a clock. “Or, are they peddling horizontally, from 3 to 9 and 9 to 3, which means they are shifting weight from hip to hip to put more pressure on outside of the foot that, in turn, puts more pressure on the knees?”

The fix might be a combination of skills training to help the bicyclist get to a smooth, even, vertical stroke, while at the same time adjusting the length of the crank arm, or the piece that attaches the pedal to the chain ring.

“We often find that crank arms are too long, causing the leg to extend more than it needs to,” Swan said.

Another common complaint is a sore butt.

“Intuitively, people often think the solution is a wider and bigger saddle when, in fact, it’s often one that is slimmer,” she said, pointing out the pain could be about alignment more than padding and seat width.

Once a thorough fitting is completed, Swan says she goes to work on skills training. To help the cyclist get accustomed to and take advantage of the modified bike, she will provide her or him with practice exercises and drills.

For more information about bike fitting and how it can help improve comfort and performance while reducing pain and injury, contact the physical therapy team at Real Rehab Sports + Physical Therapy.