Some exercises may help you get better at cycling. My aerobic capacity and endurance are good, but I naturally lack sprinting or raw power ability. Always have, in every sport I've done. So I use the gym to work on power and stability.
An example of a power exercise relevant to cycling: iso jump squats. These are not plyometric squats. They are basically the opposite. Instead of using stored elastic energy to bounce, you jump as high as you can, land back in a squat position, and pause for several (up to 5) seconds before repeating. You are trying to get yourself to fire as fast and as many muscle fibers as possible without bouncing. This is more difficult than it sounds, especially if you're doing it as part of a superset or complex.
True one-legged body weight squats are surprisingly hard to pull off, and mimic the narrow stance we use on the bike. Of course part of our thinking in the gym may also to be to undo some of what our daily routines do to us, so actually working your adductors via a more normal squat to give you balance in the hip may be beneficial. The vastus lateralis isn't the only muscle in your leg, and even the seemingly simple act of walking (or running, if you're so inclined) requires the synergism of many muscles.
Other exercises that have at least helped me get more out of cycling are ones that increase my tolerance for the bike. Core strength makes a huge difference for me. Planks and their variations, pushups on dumbbells (with an alternating row)...basically anything that really challenges you to either simply maintain a straight spine or resist rotation will help you at least feel more comfortable on the bike.
I think my gym work has made me better as a cyclist, but I've also been riding a lot since starting to lift again, so it's impossible to really prove. I do feel better in my day-to-day life, though, which is also quite physically demanding.
It is pretty well-established that for skill and strength in one exercise to transfer to another, the two movements have to be quite similar. ROM and speed of contraction are important here. This is one reason I take issue with the conclusions of studies which have tried to assess traditional strength training methods in terms of their effect on aerobic sports performance. What I have to explain to my clients is that basic, general strength training, while it can do a lot for the average person, isn't athletic training, or even appropriate for everyone's goals. It's just that you have to start somewhere, and the basic movements don't really change.
A quote I am fond of: If the only tool you have is a hammer, you tend to see every problem as a nail.