I agree. Stick with a double. My first road bike was a triple because I live in California where we climb for miles and I was new to cycling and I didn't think I was strong enough to need only a double. But I've since replaced my triple with a compact double. My tri bike is a regular double, like most. I'm new to tri's but I've never seen a tri bike with a triple cassette.

you end up doubling gears when you have a 3 chainring configuration. Stick with two and play with your rear cassette configuration for different set ups

Just so you get the lingo down and don't get suckered by sales, the front is called a "chainring," and more specifically, you have either a "double" or "triple." The rear collection of cogs is called your "cassette." Technically yes, you can have 9 in the back or 10. I imagine you are looking at Shimano (Campy has had 10 for many years and did SRAM ever have 9?). Any cassette with nine gears or "rings" in the cassette is very much "last year’s" model, maybe 3-5 (?) years old by now. Nothing wrong with it at all – they work just fine. But Shimano moved to 10 speed/rings in the cassette a few years ago, and Campy has recently moved to 11. However, you could get a triple in front and 9 rings in the rear cassette but I suspect it is an older group set as most/all new bikes now are put out with the updated to the 10-speed version. If I saw a triple with 9 in the rear, I would bet you money it has sat there and sat there and sat there because most competitive riders do not need a triple and that bike with an older group + a triple has just sat on the sales floor. There is nothing mechanically wrong with it; it just won't move for sales.

I'd replace "hills" with mountains, as in, you ride in Colorado or up and down Mt. Washington. You should go with a double. On a road bike or tri bike, a double will work (IMHO) for 90% of riders on 90% of courses. If you go with a triple, you will outgrow the need for the smaller chain ring within the first season and you'll want to dump it, well, because all of the cook kids have doubles. ;) And it's not as easy as just switching out cranks/chainrings (and cranks are very expensive). You'd have to get a new front derailleur (for sure) and shifters, so changing between triple and double is cost-prohibitive. To do so would basically mean buying a new groupset.

This may bring up more questions than provide answers, but there is an in-between that hasn't been mentioned. First, go with the double. Then, in the rear, get a really big cassette, like 12X27. These are your gear ranges. Without getting way too techincal, bigger numbers = easier to pedal. I know it's counter-intuitive, but trust me: I'm from the Internet. 11X23 is for strong riders/flat courses. 12X27 is for hillier courses or for people who like to spin high cadence. Try this out: When you go test ride, ask what cassette they have on it? Then, when you ride, drop it down into the front chain ring and bring the rear cassette all the way up the cassette and see how "easy" that is? If that isn't enough, the other option is a compact crank set (as kpollock rides). It is still a double, but "Compact cranks are finally coming to the forefront as a viable option for riders of all abilities to consider. Anyone living in mountainous or hilly terrain should give serious thought to the benefits of a compact crankset." Please read this article about gearing and compact cranks.

+1 But you gotta sell it! You can't hesitate when you drop chain rig configs and rear cassette numbers. If you hesitate or garble it, you'll be Outed as a Poseur. . . . .

WHAT?! Stop the presses! I went back and looked at our boy's posts here and first, bezsimon is a dude and he's six foot freakin two. Do not, under any circumstance, even conisider a triple and you have no biz riding a compact. I'm just bustin' balls, but c'mon, you're a grown ass man talkin' about a triple or compact?! GTFO and ride a double with 175mm cranks. Much love :)

Here are 2 things you can take to the bank, pure fact, not opinion:
1. As stated earlier, the ones in front are chainrings, either double or triple, and
2. if you want roadies to despise you even more than they hate the average triathlete, get a triple.

Thanks for all the info. It seems its fairly clear cut that the double "chainrings" (see I´m learning:)) are the way forward. This is a whole new world for me - I didnt even know doubles existed til a week ago!

With the Shimano Ultegra there are various choices for the rear cassette - but im still thinking the range of 12-27 would be best for me as yes I do live in a mountainous place - Tenerife island to be precise which is basically one massive volcano (3718m high for those interested!) - I live at the coast which basically means as soon as you move away from the coast the only way is up! So whilst yes I´m 6´2" and about 85kg is this the cassette i should be looking at?

Best wishes
Simon

with tripple... i dont know it just seems like there are many "wasted" gears.... you can change a gear(or two!) and feel nothing at all... i live in colorado too, and compact double is just fine.
my .2 cents....

I agree. My bike came with a double ring up front, and 11-23 in back. Hills were ridiculous at first, but over time I got stronger & now it's fine.

I'm with you. The only advantage I see with the double is not getting teased. :)

It's a matter of riding preference, too. I like a cadence in the 85-95rpm range whenever I can get it, and on long rides I find spinning up hills takes a lot less out of me than mashing through at 60 or 70 rpm.

Article on cadence that might help convince the skeptics. Or not.

When I eventually graduate to a tri bike, I'll probably go compact, but with a nice big chainring in the back to let me spin spin spin! :)

jono