Have been injured for over two months now with severly twisted right knee tendons, muscles and ligament.
Back on the bike for the first time yesterday, this is how I felt.

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Hey, good luck,

I'm on the same boat,

surgery for ACL "rupture",

lucky us, riding a bike is the first physical activity indicated for knee injuries

need to be careful not to catch a tendinitis because muscles around the knee that guide the patella have been weaken.

Funny how cycling is often regarded as a sport easy on the knees. Do they mean leisurely rolling along? Hard riding can be taxing on the knees. Seems ample time to warm up is one of the important rules to abide by. I actually had good results with some massage oil applied before heading out.

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This is definitely easy for the knees, even when riding hard and a lot.

Soccer, tennis, basket or running are a lot harder for the knees, a lot.

Tendinitis is the most common in cycling but this is nothing if you compare to cartilage, meniscus or ligament issues.

The only bad thing in cycling is the number of leg revolution. You have to start with a healthy knee because if you have a bit of "play" in the knee, cycling will definitely make it worse.

I did ride my bike as a rehabilitation before surgery of my ACL, and I had a bunch of play in the knee, and I caught a tendinitis in 3 rides.

It would depend on the gearing you use and the efforts.
Use lower gearing and higher cadence until the muscles get stronger around the knee.
I did have an ACL tear but I used cycling to rehabilitate it. I did not get an operation to repair.
It's been 15 years now since I tore it skiing.

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I never took drugs to improve my performance at any time. I will be willing to stick my finger into a polygraph test if anyone with big media pull wants to take issue. If you buy a signed poster now it will not be tarnished later. --Graeme Obree

Cycling is not only harmful to the knees due to repetition as Sammy Sanchez suggests and it is misleading to suggest cycling is not hard on the knees "when cycling hard and a lot". It is actually very demanding on the knees when riding like I guess most of us do. People often forget that cycling requires very strong muscles contracting across the knee. Add in to that co-contractions (e.g. the quads and hamstrings contracting and being active at the same time as each other when delivering power) and you can very quickly get very high contact forces and contact stresses in the various tissues of the knee.

Just because cycling isn't weight bearing in the same way as running does not mean forces acting in the knee are not high. It is just a different mechanism of producing high joint contact forces.

Cycling for rehabilitation is not intended to be anything like most of us would enjoy or be happy with. Cycling for rehab is mainly designed to get range of motion back (with very very light cycling) and to start to gently get the various muscles used to being active again. I would suggest really attacking more general knee rehab exercises suggested by your physio before trying to do too much on the bike. Get the knee feeling strong and settled again in all other walks of life (such as going up and down stairs) and don't be fooled into thinking cycling is easy on the knee

I had surgery in both knees now. The last one, 4 months ago, acl.

Cycling is good to recover movement, strenght should be recovered with proper exercice, not with cycling. Using the seatpost a bit higher has worked for me in the first rides, less pain in the knee when pedaling.

Try to recover properly before running the bike as a treatment, it's not, it's a part of it, not it. Use the stationary machines in the gym, small weights, increase slowly, focus on the movement.

And btw, %#&k the knees.