newbie question

1 ring.

There is an additional set of chainring bolt holes on the inside for the smaller granny ring.

3 ring gives you more easy gears for big hills. If you live in a relatively flat area or have super strong knees and legs then a 2 ring is fine. If you love spinning up hills then 3 rings is probably better.

Thanks, but I'm not stupid, I can count rings. I meant performance wise. Why would you want over the other? What are they used for? etc...

The third ring will give you alot lower gear combination therefore making your life in the hills a lot easier. The third ring will not be of any benefit to you unless you are climbing...or you like spinning on the flats at 300 rpm's. (That last bit was a joke 😉 ) Some people would really benefit from the third ring, like me as I am not a little guy (6'4" 215lbs) but are too stubborn and tying to be macho to get the third ring. But at the same time I feel like having a double is making me a stronger rider and I am getting better conditioning by having to work harder on the climbs.

TrekCyclerChic said:

Thanks, but I'm not stupid, I can count rings. I meant performance wise. Why would you want over the other? What are they used for? etc...

TrekCyclerChic said:

Thanks, but I'm not stupid, I can count rings. I meant performance wise. Why would you want over the other? What are they used for? etc...

It's about gear inches. The smaller granny ring allows lower gearing for hills if you need it. You can get low gearing with 2 chainrings, but the triple also allows low gearing and close ratio spacing. For example, a 13x29 cog cassette and 39 tooth small ring(double) = a low of 36 gear inches. You can get the same thing with a a 13x 23 cassette and a 30 granny ring on a triple, with smaller jumps between cogs,so pedaling efficiency is better.

also there is the factor of weight, the double is lighter than the triple. Some people will also argue about the q factor, which is the measure of distance between the crankarms. The last thing is how well the thing shifts. I don't think this would be an issue if you kept things well maintained, but can become an issue if things aren't kept up with. Compact cranks seem to overcome the problems of the triple and give you the lower gear combinations, it is basically a double chainring, but instead of a 53/39 upfront it's a 50/34 or 50/36. Just something else to think about.