Authors: Tim Farin and Dr Carolin Collin
Wearing a knee brace on his right knee in the German Bundestag: this is how Finance Minister Lars Klingbeil (SPD) appeared in September 2026. On Instagram, he revealed what had happened: the politician had suffered a cruciate ligament tear and jokingly wrote off his football career. Hashtag: Gravelbike. The press office later explained that the politician had tripped over a stone in the woods and injured himself in the process. The diagnosis was a torn posterior cruciate ligament.
Many people are more likely to associate a cruciate ligament tear with contact sports such as football or handball than with cycling. Other parts of the body (collarbone, shoulder, skull, hand, arm) are more commonly affected. But the ligament that connects the thighbone to the shinbone can also tear whilst cycling.
How does a cruciate ligament tear occur whilst cycling?
“A cruciate ligament tear whilst cycling is usually not caused by the pedalling itself, but by a fall,” says Prof. Dr Frank Hildebrand, President of the German Society for Orthopaedics and Trauma Surgery (DGOU). In mountain biking, the risk is greater due to the more challenging terrain, technical sections and the higher risk of falling. In road cycling, the overall risk is considered lower – though, of course, a cruciate ligament tear following a fall on tarmac cannot be ruled out.
What role do the cruciate ligaments play when cycling?
The anterior and posterior cruciate ligaments are located inside the knee joint and cross over one another. Together, they stabilise the connection between the thighbone and the shinbone. Among other things, they limit excessive rotational movements and prevent the knee from being overextended.
The anterior cruciate ligament (ACL) primarily controls how far the lower leg slides forwards. It also limits rotational movements in the knee – particularly when the body is slowing down, changing direction or when the foot is fixed to the ground.
The posterior cruciate ligament (PCL) primarily prevents the lower leg from sliding backwards. It therefore acts as an important stabiliser. During normal pedalling, the knee mainly moves through a controlled flexion and extension motion. There are no sudden changes of direction, landings or rapid rotations. This risk arises in the event of a fall: when the body and the bicycle move in different directions, strong rotational and shear forces can act on the knee. This is particularly true if the foot is locked in place, for example, if it is stuck in a pedal (as in a skiing accident with fixed ski boots).
How can you tell if you have a cruciate ligament tear?
Typical symptoms include rapidly increasing swelling, pain and a feeling of instability. Some people affected report hearing or feeling a cracking sound. Later on, the knee may suddenly give way when stepping down – this so-called ‘giving-way’ phenomenon is an important warning sign.
It is important to seek medical advice. The symptoms may also be caused by other injuries. Following a fall, for example, injuries to the meniscus, cartilage or collateral ligaments may be a possibility. Associated injuries, in particular, have a significant impact on treatment and the duration of rehabilitation. In Klingbeil’s case, for example, the medial collateral ligament was also affected.
Following such an accident, you should therefore: stop riding, protect and rest the knee, elevate the leg, and seek medical attention for the injury as soon as possible. Applying cold can help relieve pain during the acute phase. Anyone who is unable to put weight on their leg, notices a significant misalignment, is in severe pain or finds their knee locked should seek medical help as a matter of urgency.
Surgery or physiotherapy?
Not every cruciate ligament tear automatically requires surgery. Whether surgery or conservative treatment with a brace and physiotherapy is more appropriate depends, amongst other things, on the stability of the knee, any associated injuries, the patient’s age, their sporting goals and the level of physical activity they wish to undertake, as well as which cruciate ligament is affected.
Anyone who can stabilise their knee sufficiently through targeted muscle strengthening and coordination, and who does not need to make rapid changes of direction, may be able to manage without surgery. If there are additional injuries or persistent instability, surgery may be a more appropriate option. This decision should be made on a case-by-case basis in consultation with the treating doctors.
Regardless of the treatment method, rehabilitation takes patience. The initial focus is on reducing swelling and pain, restoring mobility and ensuring proper healing. This is followed by building strength, coordination and endurance. Only once these fundamentals are in place will cautious rehabilitation cycling turn into proper training again.
When can I start training again after a cruciate ligament tear?
This depends on which cruciate ligament is affected, whether any other structures have been injured, whether surgery has been carried out, and how stable, mobile and strong the knee has become. Therefore, any timeframes given are only guidelines – they are no substitute for clearance from your treating doctor or physiotherapist.
According to Prof. Hildebrand’s assessment, the following figures apply in the case of an anterior cruciate ligament tear:
- Exercise bikes/indoor: usually after about 4 to 6 weeks
- Leisurely cycling on flat terrain: often after around 6 to 12 weeks
- Longer road bike rides: after about 3 to 4 months
- Mountain biking, challenging trails and downhill: best left until after 6 to 9 months
- In the case of an isolated posterior cruciate ligament injury, a return to cycling can sometimes be achieved more quickly. Light cycling is often possible after around 6 to 8 weeks, whilst more strenuous cycling is usually possible after around three months.
These are guidelines: a consensus statement on rehabilitation published in the *British Journal of Sports Medicine* reiterates that it is the criteria in each individual case, rather than the length of time, that should be the deciding factor. It states that it is not the number of weeks that counts, but whether the knee is pain-free, mobile, strong and stable.
Recovery times can therefore be significantly longer if the meniscus or cartilage is also injured. Such associated injuries are particularly common with anterior cruciate ligament injuries. Even after an operation, the graft must first be allowed to heal. Surgery is therefore no guarantee of a quick return to cycling.
Why cycling can be a good sport if you have a cruciate ligament tear
Cycling is not beneficial in rehabilitation because it helps a torn cruciate ligament to heal. It cannot do that. The benefit lies in the controlled movement and the fact that the level of exertion can be easily adjusted. This also helps to promote the renewal of synovial fluid.
- The knee moves smoothly. When pedalling, there are no sudden jerks or changes of direction. This can help to restore mobility, provided the knee is already able to move.
- The level of exertion can be precisely controlled. On the ergometer and on the roller, resistance, cadence and duration can be adjusted. This is particularly helpful in the early stages of rehabilitation: the level of exertion can be increased gradually without posing a risk of falling.
- Muscle strength is gradually rebuilt. Following a knee injury, the quadriceps in particular tend to weaken rapidly. Regular, adapted cycling can help to rebuild the leg muscles and restore general stamina. The intensity of the training is determined by the rehabilitation plan, how you feel, or medical clearance.
- Cycling helps prepare you for everyday life and sport. If you want to start cycling longer distances again, you can gradually increase the duration of your rides. This allows you to monitor how your knee reacts to the strain – without immediately exposing it to the unpredictable forces of a trail.
A small study on the load placed on the anterior cruciate ligament provides important insight into this. In a study from 1998, the loads on the anterior cruciate ligament were measured in eight participants whilst cycling on a stationary bike. Various combinations of 75, 125 and 175 watts, as well as 60 and 90 revolutions per minute, were examined. The peak load measured on the ligament ranged between 1.2 and 2.1 per cent; the average was 1.7 per cent. No significant differences were observed between the resistance levels and cadences examined.
This suggests that stationary cycling places a comparatively low load on the anterior cruciate ligament under the conditions studied. However, the study was small and was not carried out on people who had recently suffered a cruciate ligament tear – rather, it involved healthy knees. It is therefore not possible to derive a general recommendation for training from it. It does, however, explain why the exercise bike often plays a role in cruciate ligament rehabilitation.
What you should bear in mind when returning to work
First the ergometer/roller, then the road
The ergometer is usually the safer choice to start with. It’s stable, you don’t have to stop or swerve, and you can adjust the resistance precisely. Getting back into cycling usually starts with low resistance and a short, gentle session. Heavy pedalling in a high gear, sprints and cycling out of the saddle should be avoided in the early stages, unless your physiotherapist advises otherwise.
Take pain and swelling seriously
You may experience a slightly unfamiliar sensation at the start. However, increasing pain, new or significantly more severe swelling, a feeling of instability or the joint buckling are warning signs. Even if symptoms only appear hours after the session, the level of exertion may have been too high.
Outdoors, only on safe routes
Once your knee is stable enough, you can move on to gentle cycling on flat, quiet roads. To begin with, choose a route where you can stop safely at any time. You should only reintroduce uneven surfaces, gravel, tight bends, wet conditions and situations with a high risk of falling once the treating specialists have assessed that your knee is stable enough to cope with them.
Mountain bikes and gravel bikes are not the same as road bikes
On a road bike or on a smooth road, it’s relatively easy to control your movements. In mountain biking, and often in gravel biking too, however, you have to contend with sudden changes of direction, obstacles, slippery surfaces and falls. That’s why it takes much longer to get back to riding on trails and downhill than it does to resume a leisurely ride on the road.
It’s not just about being pain-free
Before you resume demanding cycling, your knee should be pain-free and mobile. It also needs sufficient strength and stability. The muscles in both legs should work as evenly as possible; a precise assessment should be carried out by a physiotherapist or sports orthopaedic specialist.
