Originally Posted by AdamSean .
I consider riding a bike 100 miles unnatural, otherwise more people would be doing it.
Given that this years Death Ride - 125 miles, 15,000ft of climbing over 5 high Sierra passes - had 3,000 riders, one could say that whilst a 'regular' century is a good goal there are 3,000 folks that sign up within hours of the entry opening six months prior to the event itself that would beg to differ at your verdict of 'unnatural'.
The Furnace Creek 508 - that **** is unnatural... 508 miles, 35,000ft of climbing across 10 passes going from near LA, across to Death Valley (and below sea level) back up over 5,000ft and back towards LA. Nuts. Stupid hard. Unnatural, bordering on just plain wrong. That you need two support crews for each rider to monitor the riders progress over the day and a bit of riding (no sleep) during Death Valley heat and wind gives this ride an A+ on the 'unnatural' ranking. It's almost the Badwater marathon of cycling. (both events are held in and around Death Valley)
Maybe our definitions are different but I see unnatural as an event that really fit riders are pushed to their limits. Events that aspire kids to dream and pin posters on their walls of, events that even good club cyclist will initially think "screw that" - those are the unnatural events.
Even an event like the Death Ride, whilst being a hard day out on the bike for even the fast lads, can, with careful pacing on the hard sections, be completed by a regular club cyclist and therein lies the difference...

I reckon if you do lose a bit of weight and keep the triple on you too could complete an event like this next year, should you so chose.
Take the above rides big evil brother - the Alta Alpina Challenge:
Long? Yes. Hilly? Hell yeah. Challenging? Damn right. Unnatural and beyond the realms of a fairly fit guy? No. Pacing, feeding, sticking to "the plan."
Once you do 100 miles and can finish in good condition, you've reached the point where you've figured out a working pacing/feeding strategy. If you hadn't figured that out then you wouldn't finish 100 miles in reasonable condition. From there it's mostly a mental thing. Can your head deal with 200 miles? 300 miles? If it can then you'll most likely finish the ride - tens of thousands of Brevet and Audax riders prove that each year as they do events of 600km in distance. Many thousands do 1200km rides - that's almost 800 miles with minimal rest. Some of the guys that I rode a recent 600km with are far from what you'd call "fit", myself included. I'm basically a 140something pound guy with 30+ pounds of beer ballast around the waist but give me a course profile and the time limits required and I'll figure out a pacing strategy and make it happen. If the required pacing strategy says you gotta go faster than what you deem comfortable with then you show up and do what you can based upon pacing that'll get you through the 'hardest' cutoff point on the route. Even if you don't make it it's not a complete failure. If you rode to a schedule you then have some data to go off for the following year.
Just across to a point of contention from your other thread. Gearing. I think that you're dead wrong on your thoughts on gearing and would be well served by keeping your triple, using the small ring when required and dealing with the negligible weight difference. You'd be far better off keeping your current cranks and taking your better half out to a
really nice restaurant instead. You never hear of riders complaining they never used their bottom gear - but that third climb on the Death Ride, the first climb up Ebbetts pass, you'll see those that mashed a 34x27 up the bottom of the first climb of Monitor pass at speed, zig zagging across the road and sitting in the shade on the steeper section - you'll hear riders complaining that they don't have a low enough gear. Pacing and gearing... pacing and gearing...
Go out, have fun, ride... You know how to do a century - you've done it before. Apply what you learned of the first one and take that bit of confidence with you and make the second ride a success too.