Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

compact cranks

Old 07-04-08, 05:06 PM
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hendrick81
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compact cranks

What are the advantages and disadvantages of a compact.
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Old 07-04-08, 05:18 PM
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Type compact crank into the search function, select "search titles only," and select the road forum as the forum to search, and you will get 119 threads.
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Old 07-04-08, 05:27 PM
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Advantages - smaller range of gears
Disadvantage - smaller range of gears
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Old 07-04-08, 05:31 PM
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Originally Posted by cyclingvirtual View Post
Advantages - smaller range of gears
Disadvantage - smaller range of gears
rock on.
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Old 07-04-08, 06:14 PM
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Originally Posted by cyclingvirtual View Post
Advantages - smaller range of gears
Disadvantage - smaller range of gears
To quote Botto, incorrect. It's a wider range (47% jump between the rings for 50/34 versus 36% for 53/39). Unless you mean versus a triple, but triples are so out of fashion that only people like me run them.
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Old 07-04-08, 09:54 PM
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I have a great range of gears with my 50/36 combined with my 11-26 cassette. Works very well for racing too.
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Old 07-04-08, 09:57 PM
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Originally Posted by Landgolier View Post
To quote Botto, incorrect.
+1
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Old 07-05-08, 04:28 AM
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Originally Posted by Landgolier View Post
To quote Botto, incorrect. It's a wider range (47% jump between the rings for 50/34 versus 36% for 53/39).
Right, it's a wider range, which is good; it's also a bigger jump between the two chainrings, which can be bad. The quality of that shift mainly depends on the crank itself (my 50/34 actually shifts a bit smoother & more dependably than the standard 53/39 it replaced), but the important part is that the ratios see a bigger jump.

Say that, on the 53/39, maintaining your cadence through one FD shift means also shifting the RD three or, possibly, two cogs to get another ratio that's close to the one you were pedaling a few seconds earlier. On the 50/34, you'd have to shift the RD three or four cogs for the same result.

That ratio jump also depends on the gearing of the cassette. If the whole thing is in one-tooth increments, it's hardly an issue; if it starts jumping by 2- and 3-tooth increments, you'll notice the gaps in ratios even more with a compact than a standard.

So here's the pros & cons as I see them now:

A compact can get you a wider range, and can give you a lower low gear and retain a tall high gear depending on the cassette. It can also give you a slightly wider range than, or similar range to, a standard crank if you get a narrow-range cassette, but with finer increments between each cog.

But, changing chainrings on a compact, especially a 50/34, is definitely a bigger jump in ratios. You may end up staying on one chainring more often just to cut down on simultaneous front-rear shifting.

Those are the aspects I'd weigh against each other.
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