Shewbikes- I don't know if this will help you, but for core strength, I lift weights and do counterweights as well at the gym. I am fortuneate that I have a cycling friend who is a trainer at my gym so she set up a program specifically designed to meet my requests.
I wanted a program to increase endurance and build lower body strength (i.e. legs). If you want I will send you on your own message a copy of the program.
The key for us cyclists is not to build muscles for looks, rather to strengthen them. So, rather than increasing weights, you increase sets. I have been doing this program (with a few modifications in the past few weeks)since last November and have found that I am stronger on long rides and not as tired when I come home after a fast ride.
Most of the people I have met in the gym are not cyclists so they don't necessarily know what you need. To me that is the most important part!
Let me know if you want to see what I do! I have cycled 1941 miles as of Yesterday since January 1st and feel the best I've felt in years!![]()