At what point do you consider a route hilly?

1% average gradient would be the start of hilly for me and 2% would be really hard, again for me.

So, a 1% 100 mile route would have 5280 feet of climbing and a 2% route would have 10,560 feet. If you anyone lives in Florida, it is nearly impossible to get a 100 mile 1% route whereas where I live, it is almost impossible not to have a 1% route becasue the Appalachian mountains are torture.

The hilliest I ever recall was registering 13,000+ feet on a 125 mile ride but typically log 8-10,000 feet on my Brevets.

The type of climbing or road grade is probably more important to gearing selection. In the western part of the USA, the grades are relatively shallow at maybe 6-8% but they are long (10+ miles) whereas in the East, they are steep (10-16%) and much shorter (1-5 miles). A route in the West might have the same average gradient as a route in the East, but I will need much lower gearing for an eastern bike route due to the severity of the steepest gradient but on a 15% slope, gearing is irrelevant for me because I am grinding away no matter the cogset. Out west, i would probably need no more than a 25 tooth cog and would favor aerodynamics whereas in the East, I'd need a 28 or 32 cog and would focus on lighter weight if give a choice in wheels.

I did a 104-mile ride last summer with 6,200' of climbing. I would consider that to be fairly hilly, but certainly not mountainous by any means. There were long drags, plenty of little, almost constant, rollers and a few long, steep hills on that route. It was a mix of N.E. Ohio hill types on or near the glacial terminal moraine.

The spacing, steepness and length of the climbs have as much to do with whether a given rider considers a particular ride to be 'hilly'. A century with one good 5000' mountain to get over in the middle of the ride may or may not be considered hilly if the rest of the ride is pancake flat. A century of constant steep, but short, climbs that added up to 5000' would be considered hilly by most riders.

I agree with Weatherby regarding climbs and gearing. It should be added that different types of riders prefer a certain type or types of climbing. Some riders do not consider the long, shallow 'grinds' to be climbs at all while that same gradient might really put the hurt on the next guy in the pace line. A steep, punchy climb may suit one fellow and his riding partner might struggle on that same wall.

It's all...relative, OP, like you said in your first sentence.

Brian Toone, one of STRAVA's climbing statistic record holders, would probably call a 10,000' century 'flattish' while my legs would definitely term that a very hilly/climbing ride.

Thanks Weatherby and CAMPYBOB, I read a similar thread from searching Google before and someone said,

Hilly = 'number of feet climbed is close to the mileage times 100'

People seemed to agree with it generally. Does it seem accurate at all in your experiences, or is it just wishful thinking that you can tidy up a messy question with a convenient round number equation?

Well, if I rode one mile and climbed only 100' I sure as Hell would not call it hilly. If I rode 2 miles and climbed only 200' I would not call it hilly.

And like I said...I would call that 6,200' of climbing I did over 104 miles 'hilly'. So no, I would not agree with that blanket statement. I don't think there is some magic formula to define 'hilly'. There are too many variables. Age. Conditioning. Speed. Gearing. Goals. Terrain. Mileage. Even wind conditions.

I'm kind of reminded here of Nassim Taleb's idea that you should be careful of the sort of thing that you apply an "average" value to. There was a route some friends of mine did in a part of England near Sheffield - which is very hilly - but which had a net drop in race altitude. Needless to say that that wasn't how it felt to those who actually had to ride the race that day!

100ft for 10 miles is flat
300ft for 10 miles is minor rolling
600 ft for 10 miles is hilly
1200 ft for 10 miles is mountainous

Then there are grades, but those are not opinion, rather just a number.

It varies. Most of the surrounding area in which I live is quite flat. If I get of town, there's quite a hilly suburb which has some very step inclines within very short distances. I definitely consider that hilly, as I get quite a workout whenever I ride over there.

I generally count my routes hilly is if I try to talk and my voice just alters all around since its so damn bumpy! Yes I know my technique stinks haha!

In West Texas, hills weren't much of a problem, since there were few of them. I am in Arkansas for the present time, and it's nothing BUT hills. It starts getting hilly as soon as I leave the carport. It is kind of "good news, bad news". Good news is I'm building stamina and riding on the flats is a breeze. The bad news is, there aren't many flat places to ride...