With cycling it's even less understandable because a 100 mile ride is - from my experience at least - not in the same league as a marathon in terms of physical challenge. It's a piece of piss by comparison.
A little off topic for the RideLondon thread, but this has always been something I've wondered - what in people's opinion
IS the cycling equivalent to a marathon?
I've never been a keen runner, but did it from time to time; mainly a something to do to keep fit when I couldn't ride, or when I'd foolishly entered myself in an event that I needed to train for; and was capable of running 5K without needing planning and could do a 10K in comfortably under an hour if I gave myself 4-5 weeks to prepare. I've since quit for various reasons, but while I was still running I figured that one day I'd build my fitness up and eventually try a marathon, but that I'd give myself at least 12 months to get to that stage by slowly going up through the distances. And I know plenty of people who were much less fit than me who have done similar, in fact some of them started from zero - e.g. couch to 5K.
Now for cycling, while many on this forum might look at 100 miles as being nothing special, I'll admit that even though I consider myself a keen cyclist, I've only done a century twice and both of those were in "events" - RideLondon 2018 and Tour of Cambridgeshire 2019 (did RL 2015 but only got to do 93 miles, though would have been able to manage the full 100 had the full route been open).
So given the couch to 5K comparision for runners, do you think a member of the general public could build themselves up to a century in less than a year if all they were currently capable of doing currently was a pootle down the shops? Or maybe a fairer question would be to ask someone who was already quite fit, but didn't do any cycling, how far do you think they could manage given 6 months (the time between the ballot draw and the event) to concentrate just on the bike - 100 miles, 120, 150, 200?
Other ways of looking at it - given that a century ride is 3.814 times the marathon distance, do we feel that running is almost four times harder than cycling on the body? If not, what should the multiplier be? e.g. if you think it's five times harder, then the cycling equivalent would be about 130 miles, but only three times harder would mean just under 80 miles.
To be clear, I have no answer to this question myself, I'm just interested in other's opinions.
Mod note: This part of the discussion has now been moved to a dedicated thread here: https://www.cyclechat.net/threads/the-cycling-equivalent-of-a-marathon.257534/ Please head over there to continue and keep this thread for Ride London. Thanks