240 km on a roadbike?

Is 240km doable on a quality road bike in a day?
Have you perhaps tired such feat before?
24 km/h is almost idling away on a road bike so it should be no problem to do this whole thing in 10 hours... piece a cake. Or am I off beam here?

I used to help support a group of riders who did 80 - 100 miles a day but this was in very hilly country and it took about 10 hrs. I would suggest you go see how far you can do in 4 -5 hrs if you are already quite fit and used to cycling. Remember you will need support crew or else you will need to carry tools, spare tube, LOADS of water or electrolyte drink and food.
Good luck.

very doable. it will be a long day, but it is something you can manage. in america we have double centuries (200miles/322km) and i have done one once, so i am sure 240km is doable. comfort is key. you need to be comfortable on the bike. use 25mm tires, and make sure everything is comfortable. even a small thing will just kill you after being on the bike that long.

I can't give you any personal experience, but I do know a yearly ride in Melbourne (australia) called "around the bay in a day" with a 250Km and 210Km options, which often sells out months before the event.

Evidently it's possible to do, because over one thousand people manage to complete it.

Maybe give their training schedule a try, to see if you are to the challenge
http://www.bv.com.au/great-rides/40602/

And here's an useful guide to building up your endurance:
http://www.bv.com.au/bikes-and-riding/10...

I'm an experienced cyclist and I often cycle 90 km but even that is pretty hard work if you're maintaining a good tempo. In my opinion 240 km in one day is outwith the scope of anyone except a very proficient cyclist who has done some serious preparation. It would also depend on weather conditions- if you had a strong wind in your face it wouldn't be possible.

You can do it if you train for it. Any one of the "how to train for a century" plans will work. Personally, I am planning to ride 200K on my 60th birthday.

HTH