This is a good point that I never considered. With the century, you have a lot of hours to think and stay focused. Not to mention manage your calorie and water in-take. I realize the same applies to a marathon too, but it is a shorter length of time.
I’m curious what a lot of people think the difficulty ratio is. I did see some thoughts up-thread; what do the rest of you think? Would the bike ride have to be 200 miles (~7.5:1)? How about 262 miles (10:1)? 50million suggested 340 miles (13:1). I’ve never done either, but 10:1 is my WAG. Riding 30 miles takes a while, but it doesn’t seem as demanding as running 3 miles (5k).
I’ve done both and I have to say that the marathon was the most difficult for me.
I put it in that order of difficulty because the marathon was hardest on both my mind and my body; the century was easiest because, as mentioned upthread, at least there were periods of rest where I could coast and catch my breath. That wasn’t true for the marathon.
A good intermediate for me was a longer sprint triathalon (meaning, shorter than a half iron man) - difficult because of the switch in activities (you’re done running, but wait - instead of stopping, it’s time to bike now), but fast enough not to really hurt.
I don’t think there is any doubt that the marathon is harder than the century. The marathon just beats you up. That being said, I’ll suggest that there are cycling activities that are harder than comparable running activities:
I’ll say that racing in a 60 minute criterium (and not getting dropped) is harder than running a 10K race.
I’ll say that racing a 60 minute cyclocross race might be the hardest thing that any cyclist can do. That’s just a crazy painfest.
The two events above might not be as hard on the body as a marathon, but the sheer intensity of the effort involved for the 1 hour cycling events is pretty high. harder than running.
Long periods, running is harder. Shorter periods (say 1 hour), cycling is harder due to the extreme intensity levels.
Not toodling along? Anyway, you also have to worry about flat tires.
I talked to my Wife about this, and she agreed. There are a lot of things that can be factored in, but everything being equal (same weather, same training, same types of courses, good equipment) she feels the century is easier.
You can get into a nice rhythm on the bike, and do it virtually forever. Just keep riding, eating, and drinking.
A reasonably fit cyclist with enough time could ride 150-200 miles 4 days in a row. Cycling is incredibly efficient, and there’s no real impact on joints, muscles. You’re just turning your legs around. Running hurts.
You need to introduce more effort to the cycling. . .that’s why we were saying it might be more like riding up a grade for 100 miles. Or riding into a stiff wind for 100 miles. Or, introduce racing.
I guess my post wasn’t too clear, I meant to suggest somewhere between 150-175 miles on the bike to be equal to a marathon. I agree with others that it’s really hard to compare. I came up with my guess by thinking to myself, “Self, if your good buddy asked if you wanted to run 26.2 or ride today for training, at what point would you say “run” instead of bike.”
Not toodling along? Anyway, you also have to worry about flat tires.