Stupid question I know (if you know the answer), but whats the difference?

Double: 53/39

Compact: 50/34

Usually, you can get other ratios.

They’re both double (i.e. two chainrings), but a ‘normal’ double usually has a 53/39 tooth rings and a compact 50/34. For the average punter a compact is probably more suitable for general riding around.

if you live in holland go for a standard 53/39. if you live somewhere with hills, go for compact

My winter bike has a compact, summer has a standard double. Having been on the winter bike and recently changed to the summer I think I prefer the compact, always used to prefer the double.

Just find myself up the top of the block in the big ring, or changing down to the inner and being at the other end of the block. Compact you can just keep it in the big ring 90% of the time.

so they have different number of teeth/ratios?

Compact is 110mm BCD (bolt circle diameter – same as old MTB), normal road double is 130 BCD.

so they have different number of teeth/ratios?

In effect yes – the smallest inner ring you could fit on a normal double (130 BCD) would be 39 tooth, the smallest ring on a compact will be 34 tooth. Usually a compact will have a bigger gap between small and big ring, so give a bigger range of gears, but with less ‘continuity’ between them.

so they have different number of teeth/ratios?

Yes. Compacts are lower geared than normal doubles, so better for those with normal, rather than racer, leg muscles.

In effect yes – the smallest inner ring you could fit on a normal double (130 BCD) would be 39 tooth, the smallest ring on a compact will be 34 tooth

Not quite, you can get a 38t on a 130mm BCD, and a 33t on a 110mm, but yes.

Oh yes you’re right – I was “top of my head”-ing 😉

Double / Triple refers to the number of chainrings (2 or 3)

Compact or non compact refers to the size of the chainrings.

A compact has smaller rings as above.

You can get doubles and triples in both compact and non compact.

thread resurrection!!

Right about to pull the trigger on a SRAM Force chainset. And the options are (as stated above):

Double: 53:39
Compact: 50:34

My current road bike has a triple 52:42:30 and i hardly use the small ring, and spend most of the time in the big ring (obviously on the road). I am thinking I could actually go bigger than the 52 as sometimes i feel I need a little more so should I go for a 53:39?

EDIT: I suppose I need to consider what casette I am going to use too?

One thing to consider though is that this is for a cross bike, which I will also use for commuting. So will the 53:39 limit me in any way off road? Not sure what the size of my MTB triple is? prob 22/32/44 or 24/34/44? Spend most of the time in the middle ring on that set up.

my cx bike has a 34×27 lowest and I have had to get off and push on a few hills that I can ride up on a mtb with a 22×27 granny…

The other thing you need to think about is that your MTB (probably) has 26″ wheels, effectively lowering the gearing.

It’s best if you work it out in Gear Inches using a handy calculator

http://sheldonbrown.com/gears/

Doubles are for men
Compacts are for girls.

definitely a girl then,can’t you see the breasts….
or are they moobs

A double is what I have.

A compact is what I’ll be wishing for in the latter half of the Virgin Money Cyclone in June…

so what should I get for a bike that will mainly be my commuter, but I may give it the odd shot offroad?

I am now swaying towards compact but worried that I will need bigger ring up front as my 52 leaves me wanting more on the road, but I guess if I am running cross tyres these will slow me down a bit.

My road bike current has 12-25 cassette, what are typical for crossbikes, and what will give me more power if I drop from a 52 to a 50 upfront?

Get a compact with an 11 tooth instead of a 12 tooth cassette.

thats what I built my road bike up as

compact double with 11 tooth cassette, makes sense to me

Buy a compact – if you can spin out 50/12 then you should be getting sponsored.

For a CX bike, compact. For a road bike, double.
IMHO

You’re all wrong! the correct cross configuration is 46 – 38 with a 12 -27, 11 -28 or 11 -25.

Get a standard, you can ride all day in 39. If the hills are too hard change the cassette to a 27 max.

I never like what ‘seems’ like a big drop from 50 into 34

My winter bike has a compact, summer has a standard double. Having been on the winter bike and recently changed to the summer I think I prefer the compact, always used to prefer the double.

You say that now, but I think the change is always horrible. I used to swap but bit the bullet and went standard on all bikes.

Compact with 11-25 here, works well for me.

Compact for me sportives and racing. I have a 12:27 on the back too. I’ve never reached the point where I thought I needed higher gears, I’d have to be over 50mph and still trying to accelerate! I find it much easier and faster to spin up hills rather than grind (coming from mtbing).

I’m no where near as strong, fit or as quick as a pro so I’m not sure why I would want the same gearing.

I can keep up on most grop rides riding a cross bike with a 46 at the front. Fine today, even touching 40mph.