Knee Pain From Cycling: Bike-Fit Mistakes That Hurt Your Knees

Your knees turn the pedals thousands of times a ride

Cycling is often recommended as a knee-friendly sport, and for good reason: there’s no pounding and no sudden twisting. That’s why so many Singaporeans take to the park connectors, the round-island route and weekend rides out to Changi or Kranji. But there’s a catch. On a typical ride, each knee bends and straightens thousands of times in exactly the same pattern. If that pattern is slightly off, small stresses add up quickly.

Most knee pain from cycling isn’t an injury at all. It’s the result of a bike that doesn’t quite fit, or riding that ramped up too quickly. The usual suspects are:

• A saddle that’s too low or too high
• A saddle set too far forward or back
• Cleats that twist the foot
• Feet set too close together or too far apart
• Cranks that are too long for your legs
• A sudden jump in distance, climbing or intensity

Where your knee hurts usually points to which one needs adjusting.

Start with the table below to match your pain to the likely cause, then use the home check to fine-tune your bike.

Where it hurts tells you what to adjust

These are starting points, not rules. Pain that doesn’t respond to small changes, or that comes with swelling, locking or giving way, needs a medical assessment. For runners with similar patterns, see our guide to knee pain after a marathon.

The six most common bike-fit mistakes

1. Saddle too low

This is the most common cause of pain at the front of the knee. With a low saddle, the knee stays more bent through every pedal stroke, which increases the compressive force behind the kneecap. A review of saddle-height research found that patellofemoral (kneecap) compression appears to rise as saddle height falls, and suggested setting saddle height so the knee is bent about 25 to 30 degrees at the bottom of the stroke to reduce the risk of knee injury.

2. Saddle too high

A saddle set too high makes you overreach at the bottom of each stroke. Signs include your hips rocking side to side on the saddle, toes pointing down to reach the pedals, and pain at the back of the knee. Small changes matter: the same review found that a 5% change in saddle height was associated with about a 35% change in knee movement.

3. Saddle too far forward or back

The saddle’s fore-aft position changes where your knee sits over the pedal. Too far forward tends to load the front of the knee. Too far back can stretch the hamstrings and the back of the knee. Adjust in small steps of a few millimetres and re-check saddle height afterwards, as moving the saddle back effectively raises it.

4. Cleats twisting your feet

If you clip in, your cleats fix the angle of your foot. When that angle fights your natural foot position, the knee is twisted with every stroke. Heels forced outwards tend to strain the inner knee, while heels forced inwards strain the outer knee. Pedals with some “float” allow a few degrees of movement and can help.

5. Feet too close together or too far apart

The width between your feet on the pedals should roughly match your hip width and natural stance. Too narrow can push the knees outwards, while too wide can pull them inwards. Pedal spacers or longer pedal axles can widen the stance if needed.

6. Cranks that are too long

Longer cranks make the knee bend more at the top of each stroke. Riders with shorter legs, or anyone with pain at the front of the knee on a bike fitted with standard cranks, may benefit from shorter cranks. This is worth discussing with a professional bike fitter.

A 10-minute home fit check

You’ll need your bike on an indoor trainer (or leaning against a wall with someone holding it), your usual cycling shoes and shorts, a phone to film with and an Allen key set. Change one thing at a time and ride for a week before changing the next.

1. Check saddle height. Sit on the saddle and pedal backwards slowly. With the pedal at its lowest point and your foot in its normal position, your knee should still be slightly bent, not locked straight. Film yourself from the side: the knee should be bent roughly 25 to 30 degrees at the bottom. If your hips rock or you reach with your toes, lower it. If your knee is clearly bent and you feel cramped, raise it. Adjust by 2 to 3 mm at a time.
2. Check fore-aft position. With the cranks level, the front of your knee should sit roughly above the pedal axle. Use this as a starting point, then adjust for comfort.
3. Watch your knees from the front. Film yourself pedalling, front-on. Your knees should travel up and down in fairly straight lines over your feet. Knees that dive inwards or bow outwards suggest a cleat, stance-width or foot-support issue.
4. Check your cleats. Sit on a table with your legs hanging. Notice the natural angle of your feet. Your cleats should let your feet sit at roughly that angle when clipped in, with the ball of the foot over the pedal axle.
5. Check reach and handlebar height. You should be able to hold the hoods with a slight bend in the elbows and without straining your neck. A position that pulls you forward can change how you sit and load your knees.
6. Ride and note how you feel. Do an easy 30 to 45 minute ride, then note any pain, where it is, and how it feels the next day.

If you ride often or the pain keeps returning, a session with a professional bike fitter is well worth the cost.

It’s not always the bike

A perfect fit won’t protect your knees if the riding itself overloads them. Look at these too.

Doing too much, too soon. Signing up for a long charity ride, switching from weekend coffee rides to daily commuting, or adding hill repeats can all increase knee load faster than tendons adapt. As a guide, increase weekly distance gradually and include easier weeks.

Pushing big gears at low cadence. Grinding a heavy gear up a flyover or into a headwind along East Coast Park puts high force through the knee on every stroke. Shift to an easier gear and aim for a smoother, quicker pedalling rhythm.

A new bike, new shoes or new cleats. Any change to your contact points changes your fit. Many knee problems start in the weeks after a new purchase. Copy your old measurements before you swap, then fine-tune.

Weak hips and thighs. Cycling builds the front of the thigh, but the muscles that keep the knee tracking straight, such as the glutes, often stay underused. Off-bike strength work such as single-leg squats, bridges and side-lying leg raises, twice a week, helps keep the knee aligned.

Foot shape. Flat or highly arched feet can change how the knee moves over the pedal. Cycling-specific insoles or wedges may help, and a bike fitter can assess this.

An existing knee problem. Early knee arthritis, an old meniscus tear or kneecap pain can all flare up with cycling, even with a good fit. If your pain began after an injury or doesn’t behave like the patterns above, a medical assessment comes first.

When to see a specialist

Most cycling knee pain settles with fit adjustments and smarter training. Book a medical assessment if:

• Pain persists for more than two to three weeks despite adjusting your bike and reducing your riding
• The knee swells, locks, clicks painfully or gives way
• Pain started after a fall or crash
• You have pain at rest or at night
• Pain is getting worse rather than better

At International Orthopaedic Clinic (IOC), knee pain in cyclists is assessed by Dr Alan Cheung, Senior Consultant Orthopaedic Surgeon. A keen cyclist himself, he has served as team doctor for the Singapore Cycling Federation and holds a Diploma in Sport and Exercise Medicine. IOC’s knee services include assessment, imaging and sports medicine treatments, and surgery when it’s needed.

This article is for general information and does not replace a medical assessment.