Well, I suppose I'm just old and out of shape, but a 7 hour century takes training for me.

I was just looking at my training log from last year and I see that after doing a flat metric century at the end of April, I didn't do any more rides longer than 40 miles before doing a very hilly regular century at the beginning of June. That one took me 7 hours and 25 minutes.

On the "performance" side of things (to the extent that I can even apply that term to my riding), I just did that same end-of-April metric century (Monster Cookie) and cut 20 minutes off my time from last year (3:35 this year) and I can tell you that it wore me out.

3000 feet over a century is not that taxing (unless its one short steep hill).

Wow! You all sound incredible. Very long distances and fast paces. Must take alot of dedication and love.

I am a slow-poke. 14-15.something mph is usually my average speed. But it is kinda hilly around here.
I will be 44 this year and have been riding since 2008, minus the winters. In ok shape for my age I think. 5'7" 175 lbs. My only exercise is commuting. I am not an athletic type at all.

Last year I did a 50 miler, and that was pretty easy, but I did train a little. It was undulating terrain that got more undulating the further west I went.

I want to try to see how far I can go with no training at all, just for fun. Just so I will know what I can handle. I'm not talking about going till I bonk, but going til I feel it is enough.

There is a cool route that runs west straight from my home to a bike shop 20 miles away and I could use that route as it is easiest for the wife to find me if I do bonk. It is pretty much up and down the whole way with the hills getting much larger the more west you go. It would be interesting to see if I could go all 62 miles for the metric century without any training just to learn my baseline limits.

I think regular commuters sometimes are not aware of their own strength and it takes a break in the routine to bring it up. I am a middle-aged chick, can stand to lose a few.... dozen...30 mi RT trip across downtown, traffic and all, holding average between 15 and 16 mph. One morning on a weekend I set out on the MUP to explore a tricky transition between two paved sections. I found it, kept going further into the park and next thing I remember I came to the end of the trail - 26 miles out. Aack!!! Well, there is no other way but back. Came home hungry as heck, ate massive lunch and proceeded with the remaining household activities.

Yes, I did my first metric century last year on my 40th birthday and I did no training to prepare. My commute is the same length as yours and my previous longest daily distance was only 50km. My route was quite flat but I did have to deal with a strong head wind for a while. It was challenging compared to the commute but not all that bad. Like yourself, I had wondered if my commuting fitness would translate into longer distances.

That definitely depends on your fitness level (and how the 3000 feet is calculated). If all you do is flat riding, hills are very tough.

UPDATE:

So I finally did a metric century, with no training other than my 12-19 mile round trip commuting.
Just wanted to see if I could do it based on my commuting only and no training rides.
Undulating terrain that got hillier during the last 30 miles. 90+ degrees and humid. Last Saturday.
It was a nice ride. Energetic, but not killing myself.
Went with a friend from church.
He does long rides, and a century back in May and I asked to go along if he was doing any long rides anytime.
He said he was doing a 60 miler Saturday. So I went along, and added 2 more miles + to make a 100km ride.
It was a blast! No problem. I still felt pretty fresh after 30 miles.
As 40 and 50 ticked off and I still felt strong, I figured it looked like I was going to make it.
So I had a great time and look forward to many more.
Only problem I had was after 30 miles, when the hills got bigger, my head would pound as I went up hills. I think it was from the heat. On flats and downhills I was fine, though. No head pounding.
Thanks for the encouragement and advice, everyone!!

the other day, after 3 weeks of commuting, I did an 80km ride without much problem in a little over 4 hours on an MTB.

my original plan was 100km but I ran out of time

i'm in ok shape (165lbs, 6'3")

A metric century isn't all that hard. It can be done in under 4 hours without too much suffering. Too maintain that pace and get a sub 6 hour full century. That becomes a true test of will power. If you don't care how fast you go then a metric century is entirely possible. A full century you could probably do but for the next few days (and the last 20 miles) you would pay with pain.

Every month or so I do a 118 mile fg ride w/85 GI and 5 cat 5 hills. What I do is take the Friday before and Monday after off of my regular 33 mile rt commute w/a 500 ft elevation drop into work and a 500 ft climb home. I work 2nd shift which means I'm pulling the meaty mileage in the cool of the evening. And yeah I end up doing switchbacks on some of the hills on the fg ride, but each time I do the ride I'm able to pull a bit more straight on.

Those weeks I do 132 commuting miles and 118 fg miles for a 250 mile week. The only downside is the length of time it takes. Sometimes, I'd rather be watching baseball, but when my vitals, and cholestral numbers, etc. come in it makes it all worth the sacrifice.

I too do a century every month, though not FG in my case (usually ride a three speed or other vintage bike). I started doing this the year before last because I realized I wasn't doing any riding other than my commute (18 - 20 miles daily). I'm not really fast; so a century takes almost all day. And sometimes it leaves me feeling pretty wiped out.

I won't say it's easy, but nor would I call it a test of willpower. If I ride 50 miles from home and turn around, I have to get home. As hard as it gets, I still have to get there. And I always do.

You're good to go! I trained for my first metric century by eating an eclair and drinking a large coffee on the ride from my truck to the starting line. Think about it -- (round-trip commute x 2.5 = 60 miles) - (8 hours of work) = easy metric century.

Even trained lots of climbing makes the century tough.

On the 28th of this month I'm doing one that goes up and over Highwood Pass TWICE here in Alberta... about 2200m (7200') of elevation gain overall.

... I fully expect to nearly die regardless of what pace I go.

I am planning a century this coming Saturday, I have 7 hrs available, I haven't ridden more than my commute since mid-May, I'll let you all know how it goes. The 7 hrs is a hard deadline so I am stopping in time to shower and get to my daughter's play no matter how far the ride has gone...

6:08 not so bad, but I was hoping for faster. In spring I was holding 18mph for 3 hrs, but apparently no can do for 5+ right now (w/o actual training). 5k feet of climbing, my phone said, just over half the climbing of my 1st century (which I rode fixed, definitely something never to repeat but worth having done in the 'someday we'll look back at this and laugh' category).

Depends on how you ride your commute, how fast you want to ride the century and the ride conditions (hills, headwind).

Generally I will consider myself ready for an event if I've trained up to 50-75% of what I need to do on the day, as long as I've had a rest day the day before the event. When I did my first century, I'd only done a little over 50mi as my longest training ride, but it wasn't an issue. I'm planning to try a 11000+ft century later this year and so far I've trained up to doing a ~45mi/6000ft morning ride without too much soreness the next day.

Trying to do a century on one ride without any kind of break is hard! Closest I have come is 87 miles doing 50 miles earlier in the day and 37 miles in the evening. First 30 miles I can do easy at a 20mph pace, but every 10 miles after that I get slower and slower and seem to exponentially require more liquids to stay cool and hydrated, especially in 90° heat with the sun beating down on you. After 50 miles my arms and back start to hurt and my speeds are reduced to almost single digits.

With that being said a century can be done without training, but it is going to be very taxing on the body and take a good chunk of time out of your day. More training will make it more effortless, at least I hope so. 60 miles is the best I can do at one time. I am going to try for a century again when it is much cooler outside.

I commute about 12-15 mi/day, which isn't much, but can still do loaded tours in which I'm riding 65-90 mi/day, no problem at all. If you're in reasonably good, but not great shape, doing a century shouldn't be much of a challenge, as long as you're not trying to do it at time-trial pace. I think most commuters could do it at a moderate pace without hurting themselves at all. Just be sure you have a very comfortable saddle, multiple water bottles, and enough carbs on hand not to bonk.