An interesting item has arisen on the 41 forum, and I thought I'd pose the question here. This is obviously a completely unscientific and very subjective comparison, but I still find it interesting, and quite fun:
How would you compare cycling distance with running distance, in terms of effort and exertion?
I was a big runner 35 years ago - but haven't been on the pavement for years, and don't plan to buy running shoes at any time in the near future. However, in a conversation with some cycling buddies a while ago I was saying that it seemed to me that running a marathon would be way harder than riding a fast century. One of the guys surprised me - said that he's run over 20 marathons, and felt that riding a fast century was far harder than running a marathon.
In the conversation in the 41 forum, folks are saying that it's about a 5:1 ratio. I.e. running a reasonably quick 10 miles is about as hard as doing a reasonably fast 50 mile ride.
If you believe the 5-to-1 ratio is about right, then we're close to "running a marathon" every time we do a 200km brevet . Funny - I've never thought of myself as being in the same league as marathon runners!