Groupset question

[xxmimixx]

Hello
I read several times the differences between the triple vs double/compact and I think I understand the difference in practice however I still find it hard to grasp on the numbers and I dont think I ever will.

So just to simplify things for me, as I understand some compact bikes are 'very close' to a triple, can someone please let me know which 'numbers' on a compact would be the closest to a triple?

Hope it makes sense!!

 

[PpPete]

The way that compacts claim to come close in numbers to a triple is in the lowest gear attainable. But more important in your choice may be which gears you spend most of your time in.

Be aware too that the term "compact" is also used to describe a frame style, now't to do with gears.

 

[xxmimixx]

I have done some long rides during the summer and on a few occasions (like for example on the L2B I came off only one the Ditching Hill - to give you my idea of steep) but I generally cant handle steep hills I am ok otherwise (on long inclines or medium hills) but would be the last of the group of riders to climb up a decent hill, as I work my way up very slowly and strenuosly with my compact.

I know that triple are heavier, slower on flat etc but I m not racing to become an 'elite' so if the triple slows me down by few minutes I dont really care.
I was dead set on getting a triple but now I am starting to doubt myself.

 

[Moodyman]

The easiest way to understand gears is via gear inches. That is, how many inches you can move with 1 rotation of your crank.

Let's say that you have a 50-34 chainset and an 12-25 rear cassette - the most common set up on a 'Compact' bike.

Your bottom gear is 34 divide by 25 x wheel circumference (in this case 27 inches). So your bottom gear is=36.72 inches.

Your highest gear will be 50/12*27 = 112.5 inches.

Apply the same workings out to a triple set up and you'll get similar bottom and top gears.

But, here's the problem. To get such as wide range between top and bottom gears, Compacts have bigger jumps in-between gears. If you're in a varied terrain, you will find that you're not always in the optimal gear.

 

[Moodyman]

To add, I've got two bikes with different set ups a) 3 x 8 triple and b) double compact.

The bottom and top gears on both bikes are near identical. But I find that the 3 x 8 gives me the right gear for virtually any terrain. With the compact, I'm often in a gear that's close but not quite right.

Hope this helps.

 

[xxmimixx]

thans Moody for attempting to make me understand...

so does it mean that even though you can get a compact as close to a triple, it's the way the gears are split that make the difference??

I could stick with a Compact but really hate coming off at the steep hills or going so slowly up them! I just thought a triple was my way round it

 

[Steve H]

Personally I prefer a triple. I'm a fairly heavy guy at 17 stone and live in a hilly area. The weight difference between a triple and compact is negligible (less than a good trip to the toilet!!). Compacts can get close to triple ratios, but not quite as low and I like to use the extra low gears. If you also get a rear cassette with a pretty big largest sprocket, you'll get up just about all hills. I have a 11-28 cassette, so the 28 biggest bit of the cassette matched with the 30 smallest chainring of the triple is a great low gear.