compact crank...what is the point?

fuzzynavel

As the title says, what is the point of a compact chain set?
Can't you just drop to your middle ring (on a triple) to get the same effect or is there a subtle difference in the number of teeth that puts the larger compact ring between the large standard ring and the middle standard ring.

Are the 2 different types supposed to have diffrenet purposes...large front crank for mainly downhill and compact for more level rides??

Confused!

Garry H

fuzzynavel wrote:

As the title says, what is the point of a compact chain set?
Can't you just drop to your middle ring (on a triple) to get the same effect or is there a subtle difference in the number of teeth that puts the larger compact ring between the large standard ring and the middle standard ring.

Are the 2 different types supposed to have diffrenet purposes...large front crank for mainly downhill and compact for more level rides??

Confused!

I agree, didn't get on at all with mine and changed it for a 53/39. Don't know the answer though...

Min

Apparently... It's lighter

unclemalc

53 or 52/39 for big gears at the top end, for hard pushing on a good length of flat and descending, with the 39 for those who can push a reasonable gear over when going uphill;
50/34 or so for those who don't want to heave such a big gear when out just having a good ride and the 34 for when faced with a bit of a climb.
Obviously it depends upon what you're tooled up with at the back but I couldn't use the big gears provided by a 53/39 linked to a 11/23 at the back and the smaller gears weren't small enough!
I use a 50/34 with a 12/25 now and my riding is the best ever.
Bear in mind I'm a heavy 52 year old, not a 10st mid-twenties racing snake....

k-dog

I was never comfortable with a triple - the big ring was a little too big for general riding and the middle ring was a little too big for climbing but too small for decent speed so I found I was always jumping between rings on the front - and the small one always felt too small on a road bike.

Just ordered a compact bike but I haven't tried it yet (apart from a test ride). I think it will work.

roger_merriman

fuzzynavel wrote:

As the title says, what is the point of a compact chain set?
Can't you just drop to your middle ring (on a triple) to get the same effect or is there a subtle difference in the number of teeth that puts the larger compact ring between the large standard ring and the middle standard ring.

Are the 2 different types supposed to have diffrenet purposes...large front crank for mainly downhill and compact for more level rides??

Confused!

the compact gearing allows one to carry near as the same range of ratios as a triple but with only two upper chainrings. a triple offers at best one gear lower and one higher.

ie 34T compared to a 42t is quite a jump.

Down the Road

This year's tour was won on a compact

fuzzynavel

The reason that I have asked this question is that I have seen a bike that I like with a compact double set at the front and 11-23 at the back and I keep comparing it to my MTB.
On the MTB I have a triple at the front and 7 at the back but I never use the inner ring at the front. I can manage with the middle ring and a large "megarange" ring at the back to get up the steepest hills I can find. The problem comes when I try to go down hill. I can't get my legs to go any faster on the highest possible gear and can't get above 32 mph.
I have a set route that I do and I aim to keep improving my times and the downhill part is not improving with the rest of the ride.

unclemalc

Chances are on your MTB you have something like a 48 on the front big ring. A 50 from a compact' will immediately increase your high gear options.
The 11/23 is a full-on road race set but with a 50/34 on the front it will give you plenty of grunt at the top end for speed, but will also allow you to go uphill at a reasonable, non-knee-splitting cadence. I need the extra from a 25, but thats your decision, based on what you know you can do on a climb.

fuzzynavel

thanks for all your help

neeb

50/36 and 11-23 is the perfect setup for me.

Effectively the same gear range as the "standard" 52/39 12-25 (except a tiny bit extra at either end). If you're pushing the gears and the hills aren't too steep you can stay on the big ring 90% of the time, and unlike 50/34 the drop from the 50 to the 36 isn't uncomfortably extreme. Also there's plenty scope for swapping to a larger cassette at the back if you want to do some serious long climbs in the alps or wherever.

Unfortunately the 50/36 combination is harder to find than the 50/34 - you'll often have to buy a new 36T chainring and swap it for the 34T. The 2 extra teeth do make a difference, the drop from 50 to 34 leaves you spinning really uncomfortably until you compensate by changing at the back (or you have to change at the back first).

redddraggon

Down the Road wrote:

This year's tour was won on a compact

Not with Compact rings though......a 110mm BCD crankset maybe. Sastre only used this so he could fit a 38t rotor ring.

McBain_v1

My dad got himself a compact chainset (he's 72) and is now getting much more out of his cycling. He didn't want a triple chainset - he felt that this was "giving in to getting old" and so the compact was the logical way to go. He rides a 50/34 with a 27/13 on the back and seems perfectly happy to twiddle away up the hills.

I'm still persisting with my 53/39 x 12/27 and am finding it adequate for most climbs.

RedAende

I was riding a 52/42, knee killer and couldn't get up hills.

Bought a compact 50/34 , just about perfect, can spin along quickly on the 50, and the 34 is just about low enough for standing and grunting up the steepest of short sharp inclines.

fuzzynavel

RedAende wrote:

I was riding a 52/42, knee killer and couldn't get up hills.

Bought a compact 50/34 , just about perfect, can spin along quickly on the 50, and the 34 is just about low enough for standing and grunting up the steepest of short sharp inclines.

I think my current triple may be a 22/32/42 setup....not sure what I have at the back....newer versions of the same bike have a 13-34 seven speed cassette...the biggest cog is substantially bigger than the second biggest cog...

I tend to use 32 at the front and about 20 (middle cog) at the back when climbing... the local 10% slope.