Knee pain from cycling: where it hurts tells you what to check
Knee pain from cycling usually comes from the bike setup, not from your knee. Where it hurts tells you where to look. Pain at the front often means the saddle is too low or too far forward. Pain behind the knee often means it is too high. Pain on the outside often means the cleats. In every case, measure your knee flexion at 6 o'clock first: 25–35° for a road or TT fit, 25–37° for a comfort fit. If the pain stays after rides, or one knee is much worse than the other, see a physio or a professional fitter.
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Where does your knee hurt?
Point to where it hurts and find your row below. Each row gives the usual cause and the first thing to measure. These links come from sports-medicine reviews of cycling injuries (Holmes et al. 1994; Silberman et al. 2005; Wanich et al. 2007).
They are common patterns, not a diagnosis. One pain can have several causes, and some are not on the bike.
Right leg at 6 o'clock, rider facing right
- 1
Front of the knee
Often a saddle too low, or too far forward
Check knee flexion at 6 o'clock, then KOPS
- 2
Behind the knee
Often a saddle too high, or too far back
Check knee flexion at 6 o'clock, then KOPS
- 3
Outside of the knee
Often cleats, then a saddle too high
Cleats need a fitter. Then check knee flexion
| Where it hurts | Often points to | Check first |
|---|---|---|
| Front, around or under the kneecap | Saddle too low or too far forward | Knee flexion at 6 o'clock (over 35° is too low), then KOPS |
| Behind the knee | Saddle too high or too far back | Knee flexion at 6 o'clock (under 25° is too high), then KOPS |
| Outside, on the bony bump | Cleat angle or float, then saddle too high | Cleats (ask a fitter), then knee flexion at 6 o'clock |
| Inside of the knee | Cleat angle or too little float | Cleats (ask a fitter) |
Why cycling hurts knees: repetition, not force
Each pedal stroke puts only a light load on the knee, much less than a running step. The problem is the count. You do about 5,000 strokes an hour, and your foot is clipped in, so the knee follows the same path every time (Holmes et al. 1994). A small error in that path adds up.
So knee pain is common in cycling. The knee is one of the most frequent sites of overuse injury (Dettori and Norvell 2006). About 50% of cyclists get overuse knee pain (Bini et al. 2011). In a group of 109 pro road riders, 36% had pain at the front of the knee in one year, and knee injuries kept riders off the bike more than any other (Clarsen et al. 2010).
The path of your knee depends mostly on saddle height, saddle fore-aft and cleats. You can adjust all three. Reviews list bike fit first among the ways to prevent these problems (Wanich et al. 2007).
The same knee at three saddle heights
| Panel | Knee flexion | Pain it is often linked to | What to do |
|---|---|---|---|
| Left | 15° | Behind the knee, sometimes outside | Lower the saddle 10–15 mm, re-measure, then 5 mm steps |
| Middle | 30° | Not saddle height. Check fore-aft and cleats | Nothing. Anywhere in 25–35° is fine |
| Right | 45° | Front of the knee, around the kneecap | Raise the saddle 10–15 mm, re-measure, then 5 mm steps |
These are common patterns, not rules. A knee at 30° can still hurt, and a knee at 15° can feel fine. The angle tells you what to change first.
Front of the knee: saddle too low or too far forward
This is the most common one. It hurts around or under the kneecap, often more on climbs or in big gears. The evidence here is the strongest. A lower saddle pushes the kneecap harder against the thigh bone (Bini et al. 2011). In a lab study of 20 riders, the lowest saddle gave the highest knee loads. That saddle put the knee at about 58° at 6 o'clock, far out of range (Wang et al. 2020).
Check knee flexion at 6 o'clock. Over 35° (37° on a comfort fit) means the saddle is too low. Between 35° and 40°, raise it 5–8 mm. Over 40°, raise it 10–15 mm, then continue in 5 mm steps. Re-measure after each change. If you have ridden low for years, spread a big change over a few rides.
If knee flexion is in range, check saddle fore-aft. A saddle too far forward puts the knee ahead of the pedal at 3 o'clock, and fitters often link that to front-of-knee pain. Pedalyze gives your KOPS offset as a percentage of shin length. Over +5: move the saddle back 8–10 mm. Over +12: move it back 10–15 mm. KOPS is a convention, not physics, so use it as a starting point.
Behind the knee: saddle too high
Pain behind the knee, where the hamstring tendons attach, is the sign fitters most often link to a high saddle. Your leg has to reach for the pedal at the bottom. Your hips rock on the saddle, and your toe points down at 6 o'clock. Both are easy to see in a clip.
The evidence here is weaker. A review found that a higher saddle did not change hamstring length in the lab (Bini et al. 2011). So this is what fitters see, not a proven mechanism. Use the pain as a reason to measure, not as proof.
Check knee flexion at 6 o'clock. Under 25° means the saddle is too high. Between 20° and 25°, lower it 5–8 mm. Under 20°, lower it 10–15 mm, then continue in 5 mm steps. The saddle height guide shows what each case looks like. If knee flexion is in range, check KOPS: a saddle too far back has a similar effect. Under −5 on a road or TT fit (−8 on a comfort fit), move the saddle forward 8–10 mm.
Outside of the knee: cleats first, then saddle height
Pain on the outside of the knee, on the bony bump, is usually iliotibial band (ITB) syndrome. The band rubs over that bump each time your knee passes about 30° of bend, and that happens on every stroke. The force is low, only 18% of what it is in running, so again it is the repetition that hurts. A saddle set too high can make it worse (Farrell et al. 2003).
Check the cleats first. The cleat sets the angle of your foot, and your foot sets the line of your knee. If the cleat turns your foot to an angle that is not natural for you, the knee twists a little on every stroke. Too little float makes it worse. Pain on the inside of the knee often has the same cause, twisted the other way.
A side-on photo cannot see your cleats or your knee from the front. Neither can Pedalyze. This is the clearest case for a fitter. Check knee flexion at 6 o'clock too: if it is under 25°, lower the saddle as above. If it is in range, leave the saddle and get the cleats checked.
Measure this first: knee flexion at 6 o'clock
Three of the four pains send you to the same number, so start with it. Knee flexion is how far the knee bends from straight with the crank at 6 o'clock. Holmes, Pruitt and Whalen recommended 25–30° in 1994, and a review of 62 papers agreed (Bini et al. 2011). We use 25–35°, because a 2D photo cannot see small ankle movements. Anywhere inside the range is fine.
To measure it yourself: bike level, crank at 6 o'clock, heel where it sits when you pedal. Have someone take a side-on photo from hip height. See how to take bike fit photos for the camera setup.
Pedalyze measures this angle from a photo or a clip. For knee pain, use a clip: you feel the pain while pedalling, and a pedalling leg bends differently from a posed one. The clip is analysed in your browser and never uploaded.
| Fit style | In range | Borderline | Out of range |
|---|---|---|---|
| Road, endurance, TT | 25–35° | 20–25° or 35–40° | under 20° or over 40° |
| Comfort, upright | 25–37° | 20–25° or 37–42° | under 20° or over 42° |
What a photo cannot tell you, and when to see someone
A side-on photo gives angles in one plane. It cannot see your cleats, your foot angle, or how your knee tracks from the front. It cannot spot a leg length difference. Pedalyze's error against a goniometer is not measured yet. A study of the pose detection method it uses found errors of 3–9°, worst at the foot and ankle (Bini et al. 2024). The knee bands are 10° wide, so a reading in the middle is safe. A reading near an edge can go either way.
Use the numbers to rule out the simple causes, then stop. See a physio or a professional fitter if the pain stays after rides, comes back on every long ride, is much worse on one side, comes with swelling, or is still there after two or three careful changes. A fit helps comfort, but nothing shows it prevents injury. In a survey of 849 cyclists, riders with a fit reported less pain, but not fewer injuries (Priego Quesada et al. 2019). Not sure which kind of fit you need? See is a bike fit worth it?
How to fix it: one change at a time
Each change moves more than one angle. On a 73° seat tube, raising the saddle 10 mm also moves it back about 3 mm, which changes KOPS. Work from the saddle forward.
- Before you touch anything, write down where it hurts, when, and on which side. "Front of the right knee after 2 hours" is useful to a fitter.
- Measure knee flexion at 6 o'clock. Fix saddle height first.
- Then measure KOPS at 3 o'clock and fix saddle fore-aft.
- Make one change. Mark the seatpost with tape so you can go back.
- Ride two or three times, then re-measure. A new height can feel strange at first, even when it is right.
- Pain on the outside or inside of the knee? Book a fitter for the cleats, and bring your numbers.
Mistakes that keep the knee hurting
Most of these come from wanting to fix it fast.
| Mistake | What it does | How to avoid it |
|---|---|---|
| Changing saddle, stem and cleats on the same day | If the pain changes, you do not know why. If it gets worse, you cannot go back. | One change at a time. Tape on the seatpost, a photo of the cleat before you move it. |
| Raising the saddle for front-of-knee pain without measuring | If your knee was at 26°, you are now at 23°. You swapped one pain for another. | Measure first. Raise the saddle only if the reading says it is low. |
| Measuring with the crank short of 6 o'clock | The knee is more bent, so the saddle looks too low when it is not. | Line the crank up with the seat tube. In a clip, Pedalyze reads the knee at the 6 o'clock crank position on every stroke, so one short frame does not matter. |
| Pointing the toe for the photo | The leg looks longer, so a high saddle looks right. | Pedal normally in a clip. In a photo, keep your heel where it is when you ride. |
| Treating pain on one side as a fit problem | The saddle is the same for both legs. One-sided pain often has another cause, or comes from a difference between your legs. | See a physio or a fitter. Do not lower the saddle for one knee. |
| Riding through it | Overuse pain rarely goes away under the same load. | Ride shorter while you test a change. If the pain stays after rides, stop adjusting and see a physio. |
Preguntas frecuentes
- Why does the front of my knee hurt when cycling?
- Usually because the saddle is too low or too far forward. A low saddle keeps the knee bent under load and pushes the kneecap harder against the thigh bone. Check knee flexion at 6 o'clock: over 35° means the saddle is too low. If that is in range, check saddle fore-aft. Climbs and big gears often make it worse.
- Why does the back of my knee hurt when cycling?
- Fitters most often link it to a saddle that is too high. Your leg reaches for the pedal, your hips rock and your toe points down at 6 o'clock. Check knee flexion at 6 o'clock: under 25° means the saddle is too high. The research on this link is thin, so measure before you change anything.
- Why does the outside of my knee hurt when cycling?
- It is usually iliotibial band (ITB) syndrome. Check the cleats first: their angle and float set the line of your knee. A saddle that is too high comes second. A side-on photo cannot see cleats, so ask a fitter.
- Can a saddle that is too low cause knee pain?
- Yes. It is the most common fit cause of pain at the front of the knee. Studies show the load behind the kneecap rises as the saddle goes down. Raise the saddle until knee flexion at 6 o'clock is 25–35°: 5–8 mm for a borderline reading, 10–15 mm then 5 mm steps if you are out of range.
- My knee hurts after cycling, not during. What does that mean?
- Overuse pain often shows up after the ride or the next morning first. The place still tells you what to check: front, saddle height and fore-aft; behind, saddle height; outside, cleats. Change one thing and ride shorter while you test it. If it still hurts after rides a few weeks later, see a physio.
- Does cleat position cause knee pain?
- It can. The cleat sets your foot angle, and your foot sets the line of your knee. A wrong angle or too little float twists the knee a little on every stroke. Fitters often link this to pain on the outside or inside of the knee. Pedalyze cannot see cleats, so ask a fitter.
- Can Pedalyze tell me why my knee hurts?
- No. It measures your joint angles from a side-on photo or clip and compares them with target ranges. It can tell you that your knee flexion at 6 o'clock is 42°, which often goes with front-of-knee pain, and that raising the saddle 10–15 mm brings it into range. It cannot see your cleats, your knee from the front, or a difference between your legs. It is a first check, not a diagnosis.
- Should I stop cycling with knee pain?
- Ride shorter and easier while you test a fit change. Give each change two or three rides. Stop and see a physio if the pain stays after rides, the knee swells, one side is much worse, or two or three changes have not helped.
References and further reading
The pain-to-setting patterns come from the three clinical reviews. The numbers come from the studies.
- Holmes JC, Pruitt AL, Whalen NJ. Lower extremity overuse in bicycling. Clinics in Sports Medicine 13(1):187–205, 1994.
The clinical review most fitters cite: about 5,000 revolutions an hour, the foot fixed to the pedal, and the 25–30° knee angle.
- Silberman MR, Webner D, Collina S, Shiple BJ. Road bicycle fit. Clinical Journal of Sport Medicine 15(4):271–276, 2005.
A sports-medicine review of road fit, setting by setting, with the pain patterns each setting is linked to.
- Wanich T, Hodgkins C, Columbier JA, Muraski E, Kennedy JG. Cycling injuries of the lower extremity. Journal of the American Academy of Orthopaedic Surgeons 15(12):748–756, 2007.
Lists knee pain, patellar tendinitis and iliotibial band syndrome as common and largely preventable, with bike fit first among the prevention measures.
- Clarsen B, Krosshaug T, Bahr R. Overuse injuries in professional road cyclists. American Journal of Sports Medicine 38(12):2494–2501, 2010.
109 professional riders. 36% had had anterior knee pain in the previous 12 months. Knee injuries caused 57% of the time lost.
- Bini R, Hume PA, Croft JL. Effects of bicycle saddle height on knee injury risk and cycling performance. Sports Medicine 41(6):463–476, 2011.
Review of 62 papers. Patellofemoral compressive force rises as the saddle goes down; a higher saddle did not change hamstring length. Recommends 25–30° of knee flexion.
- Wang Y, Liang L, Wang D, et al. Cycling with low saddle height is related to increased knee adduction moments in healthy recreational cyclists. European Journal of Sport Science 20(4):461–467, 2020.
20 recreational riders at four saddle heights. The lowest gave the largest knee adduction moments, at about 58° of knee flexion at 6 o'clock.
- Farrell KC, Reisinger KD, Tillman MD. Force and repetition in cycling: possible implications for iliotibial band friction syndrome. The Knee 10(1):103–109, 2003.
10 riders. The knee passes the band's impingement zone near 30° on every stroke, at 18% of the pedal force seen in running. Repetition, not force, and a seat set too high can make it worse.
- Dettori NJ, Norvell DC. Non-traumatic bicycle injuries: a review of the literature. Sports Medicine 36(1):7–18, 2006.
Non-traumatic injury prevalence in cyclists as high as 85%. The knee is among the most common sites.
- Priego Quesada JI, Kerr ZY, Bertucci WM, Carpes FP. The association of bike fitting with injury, comfort, and pain during cycling: an international retrospective survey. European Journal of Sport Science 19(6):842–849, 2019.
849 cyclists. Professional and self-done fits were both linked to less pain while riding. No link with injury.
- Bini RR, Nascimento VB, Nibali A. Validity of neural networks in determining lower limb kinematics in stationary cycling. Sport Sciences for Health 20(1):127–136, 2024.
26 cyclists. The pose detection method Pedalyze uses had typical errors of 3–9° against markers, with the foot and ankle tracked worst.
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