What's the point of a compact crank?
 

What's the practical reason to have a compact crank? I know they weigh less, but what's the practical reality of the way the gearing affects one's ride and one's ability to find the right gear at the right time?

If I switch to a compact crank, would I need also to get a new freewheel with smaller/tighter gearing so I don't lose my top speed? I think my fastest gear right now is 52x14, so if I switch to a 50 or lower compact crank and a tighter freewheel (one that goes down to, say, 12), would the resulting 50x12 be faster than my 52x14? Even more dramatically, would a 48x11 be faster, or even comparable, to a 52x14?

Thanks!

It's mostly about being able to use a smaller ring to get lower gears without going to a triple. Sheldon Brown at www.harriscyclery.com has a gear inch chart.

Most bikes are over-geared for most riders. Compact doubles allows riders to down-gear to a more useful range.

When comparing gear ratios with different chainring and cog combos, it is easier to use "gear inches". A 90" gear is a 90" gear no matter what combination you use to achieve it.

On MTBs, you get a bit more ground (or rock!) clearance as well. In the years I did a lot of off-road riding, I don't ever recall getting into the big ring....

If I want to get into racing, will a compact crank with an 11 in the back put me at a big disadvantage?

I'm no daredevil on the downhills, so it's not like I need to be cranking at 55+ mph very often.

depends on who you're racing and the course. if it comes down to a 40 mph sprint finish and the guy next to you is sprinting in a 53-11 and you have a 50-11, then you're probably undergeared (assuming you could even push that). but that's pretty unlikely in the lower cats, so i really doubt you'd be at a disadvantage.

The last time I used my 52-12 combo was at least a dozen years ago during my stronger days....
I could definitely see a compact set giving me more usable, down to earth gears... :)

I am on my 2nd compact crank and wished I would have kept the first. For myself, a triple is too busy for my road bike and way too many gears that I wouldn't need. I am fairly strong rider but unless I am screaming down a hill, I was never in the 52 in front and 11-13-15 in the rear. A 110 double gives you everything you need. High enough for the average rider for the flats but better climbing options. Combine that w/ a 27 in the rear (shimano) or 29 (campy) and your knees will thank you.

I sure agree with that. I promised I'd never buy another road bike without a compact double. Unfortunately, I'm building a Campy based bike now and compact doubles are too expensive with Campy so I'm going back to a triple. I like the compact double better, however.

It didn't seem to hurt Tyler Hamilton too much...

It appears to be another non-improvement, a pseudo progress in the cycling industry to stimulate sales. As if you could not achieve suitable gearing with proper choice of chainrings and cassette.

No, my crank spider will not accept anything smaller than a 38 ring.

Well, see, there's lots of girly men out there on road bikes. And they want to pretend to be manly men, so they want doubles, because triples are for pansies. But, they're too wimpy for real man doubles, so they get giiiiirly man doubles, with little itty bitty rings to let their little legs get them up bigger hills.

Lot of truth to that. And I think I fall into the "too wimpy for real man doubles" camp........nothing wrong with that. :)

I've settled for 38/48 and 38/46 on my bikes. Stopped using 39/53 many years ago. Works just fine to get the cadence I need and go up any climb I choose. Anything smaller is just embarassing.

Yeah, a compact crank has a girly man vibe to it. But from what I'm reading the purpose was really to allow you to have a more fine-tuned range for your cassette/freewheel. With a big ass 53 in the front, most people will never use their 15, 13, 12, 11 cog gears in the back. For that's a third or more of the total range!

For what it's worth, I almost never use my small front gear anyway. I hate shifting the front, so I make do with shifting only the back almost all the time (I use non-indexed, old-skool downtube shifters). The advantage of a compact crank with a small range freewheel is, it seems, that I can find 90% of the gears I will normally use without shifting the front chainring at all. And I have more fine-tuning options within that range.

Shimano makes a freewheel (called Mega Range, available at Harris) with an unorthodox 11-13-15-18-21-24-34 range (yes, that's a 10-cog jump at the end). The idea is that once you've wimped out, you might as well wimp out all the way.

This seems like a fun and useful setup for me: The Shimano Mega-range rear freewheel and a compact 50x36 crank. It would give me (a) as much high-speed power as my current 53x14 setup (probably more), (b) a smaller range of gears for the majority of my riding so I can fine tune my gearing better for each situation, and (c) it's got that mega 34 in the back which, with the 36 in the front, would enable ultimate girlyman power on the toughest climbs. I gain more at the bottom, I gain more at the top, and I gain mor e options all across the middle. Seems like a good deal.

Another girrly man step to the plate. :rolleyes: Sure,many don't need a 11 or 12,but it's easy enough to switch a cassette.

Not 'girly' since many girls are quite happy with 39/53, maybe 'compact' is just a more current and PC term for 'granny'.

Nope, granny is itty bity third ring syndrome.

50/12 @ 80 rpm = 26.1 mph
52/14 @ 80 rpm = 23.2 mph

50/12 @ 90 rpm = 29.3 mph
52/14 @ 90 rpm = 26.1 mph

Therefore, a 50/12 @ 80 rpm will run @ the exact same speed as a 52/14 @ 90 rpm. Its a relatively substantial bump.

I have no problem with being called a girly man. Just don't call me granny.

...and to think the Tour has been won on somewhat round wooden wheels...

53 / 39 = 1.35
50 / 34 = 1.47

It's just a bigger jump from the small ring to the big one to reduce the number of overlapping gears. This allows you to have either more overall range with same spacing or the same overall range with tighter spacing.

...and to think the Tour has been won on somewhat round wooden wheels...