You might have a problem with technique. Believe it or not, you can ride a bike incorrectly and cause damage. Same for the proper seat height. If you don't have it set properly, can can cause issues. Pedaling should be a smooth motion. If your upper body is swaying and dancing at all, you're putting stress on your core and knees. You don't want that. Your hips and core shouldn't move side to side, or much at all. They should be visibly static. It should all be push/pull in your quadraceps, hamstrings, and glutes. There are a lot of youtube videos on how to set your seat height and how to "make circles". Making proper circles is not easy, nor a natural motion, but it does become muscle memory with practice. I know. I know. It's riding a bike, and everyone knows how to do THAT. If you're doing it for exercise and a lot, you could indeed be doing it wrong and causing problems.
As for rowing machines, I've used them a bit. They're good for building strength in the lower back because while the core is strongly engaged, it is a controlled, strictly linear motion. Your body isn't jiving all over the place to compensate for any weaknesses in muscle groups or in technique. Well, there is a technique, just like with any motion, but you know. You could find a gym with rowing machines with a 3-day pass or week pass and give them a go.