I have an impingement in one shoulder, so I've been working on doing long hangs. I've done hand work all my working life, but my grip strength is still crummy. Over a few weeks, I've worked up to doing 3 X 60" X 30" hangs. Goal is 10 X 60" X 30". Not easy, at least not for me. I ran across this video demoing hanging ab work:
https://www.youtube.com/watch?v=Bb-xofLVoo0
Note that he's using lifting grips, probably Harbinger. If I had to do that instead of Roman Chair, that's what I'd use.

I went alpine skiing two days ago, first time this year, big moguls with soft snow. I noticed today after my hour on the rollers that my abs were a tiny bit sore, so I planked for 5 minutes, just to see. First plank I've done in probably 18 months. Anyway, just saying that dumbbells, squats, and hanging knee raises will get you a long way with core. For cycling, you want the hip flexor involvement. That's how you lift that rear leg.

I left out Romanian deadlifts in my list above of core work. I haven't been doing them this year. Don't have time to do everything. They're really good, though.