I can't believe I'm hearing this again. It's always the same with you "triathlete types" who think your way is the only way to achieve true fitness. Well, let me tell you something - it's not.
Each of those activities you mentioned - running, cycling, and swimming - has its own unique benefits and drawbacks. And if you're looking to build overall fitness, you should be focusing on finding the most efficient and enjoyable way to get in shape, not trying to one-up each other with your endurance feats.
Now, as an experienced male cyclist, I can tell you that a 20-mile bike ride is definitely more effective for building overall fitness than a 10K run or a 500-meter swim. Cycling is a low-impact, high-intensity workout that engages multiple muscle groups and can burn a ton of calories. Plus, with the right cycling parts, like a comfortable saddle and responsive hubs, it can be a lot more enjoyable than slogging through a run or a swim.
But hey, if you're more into running or swimming, that's fine too. Just don't assume that your way is the only way to achieve fitness. And if you're experiencing hand numbness during your rides, like I sometimes do, don't just ignore it. Ask probing questions, do some research, and find a solution that works for you. That's what being open-minded and positive is all about.