Marathon on a bike

i could never do a marathon, but i have cycled 100+ miles, day after day, for... days... (6) - averaging 18mph... with luggage. So, i Personally believe that a marathon is MUCH harder than 112 miles, or anything around that number.

I did 130 in a day, that was quite unpleasant... i'd imagine 150 or more miles, by bike... at 18mph ish, (roughly 8.5 hrs on the bike) would be getting close to the pain you would feel at the end of a 26 mile run. Running is so much more intensive.

On flat, road bikes pretty much roll along at 15mph with minimal input.

i agree when i first started training after only 4 training rides going from 40 to 80 then 20 miles i could ride 100 with out feeling any where near the pain of a marathon. However bristol to london about 140 miles was probs a good equivelent even done slow that is a long ride so i think 150 miles is a bike marathon.