Compact or Standard crank?

Discussion in 'Cycling Equipment' started by rb4life, May 20, 2011.

  1. rb4life

    rb4life New Member

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    Right now I'm running a compact 50/34 with a 12-27 cassette. Long story short I upgraded my components to the new Dura Ace 7900. I went with a 11-28 cassette this time. I'm wondering if I should stay with the compact 50/34 I have or switch to the standard 53/39. I like the compact and being able to ride in the big ring on hills that aren't too steep, but now I'm curious about the standard because of the 28 cog I will have instead of the 27. On the other hand it might not be that much difference because comparing the 12-27 and the 11-28 I'll only be losing a 16 cog and gaining an 11 with the 11-28. Any advice is appreciated.
     
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  2. vspa

    vspa Active Member

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    try the search option, there is a long and complete discussion on this subject somewhere on the forum,
     
  3. daveryanwyoming

    daveryanwyoming Well-Known Member

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    As vspa mentioned this subject has been discussed many times on these boards so do some searching and you'll get a lot of opinions on the compact vs. standard crankset question.

    But having said that why change unless there's an issue you're trying to solve?

    The 50 tooth chainring on the compact paired with an 11 tooth cog is a bigger high end gear than a 53x12 so you get a bit more high end for straight fast descents or screaming tailwinds. The 34x28 low end is of course lower than your previous 34x27 but it's a lot lower than a 39x28 (33 gear inches vs. 38 gear inches and your previous low gear was 34 gear inches).

    So you get a lower low end and a higher high end than what you had before or what comes as standard gearing on most road bikes. So all you lose with the compact is the finesse of having just that right middle of the cluster gear. So do you miss the 16? Will the available combos with a standard crankset and your new cluster fill some important mid range holes you're currently missing? Have you regularly been winding out your 50x11 and really think you need a 53x11 (remember pro tour racers only started using gears like that within the last decade)?

    I'd stick with your compact unless you just have money to burn or have a specific issue with mid range gearing you're trying to fix.

    -Dave
     
  4. Eichers

    Eichers New Member

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    Hi rb4life, gearing wise a 28T (sprocket)/34T (chainring) is about equivalent to a 32/39, and an 11/50 is higher than a 12/52 or 12/53. Yes, for the middle gears there will be more variance between gear, which you need to control. Wrsto weight, well the chainrings are smaller so a compact crank should be lighter and I suspect stiffer, even though it is a 110 BCD, and the 11-28 cassette is only marginally heavier than an 11-23 or 11-25 cassette.

    There are quite a few wins for the comapact crank approach, especially as you already have a 7900 compact crank :)
     
  5. MaxRap

    MaxRap New Member

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    @font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }a:link, span.MsoHyperlink { color: blue; text-decoration: underline; }a:visited, span.MsoHyperlinkFollowed { color: purple; text-decoration: underline; }div.Section1 { page: Section1; }
    Today I came across a nice app called Bike Gear Calculator, www.BikeGearCalculator.com I had the same dilemma to get compact or not. this gear calculator gave me the answers I needed. Switching to compact now. As it turned out there are so many things to take into consideration. http://itunes.apple.com/us/app/bike-gear-calculator/id505985340?ls=1&mt=8
     
  6. MaxRap

    MaxRap New Member

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    @font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }a:link, span.MsoHyperlink { color: blue; text-decoration: underline; }a:visited, span.MsoHyperlinkFollowed { color: purple; text-decoration: underline; }div.Section1 { page: Section1; }
    Today I came across a nice app called Bike Gear Calculator, www.BikeGearCalculator.com I had the same dilemma to get compact or not. this gear calculator gave me the answers I needed. Switching to compact now. As it turned out there are so many things to take into consideration. http://itunes.apple.com/us/app/bike-gear-calculator/id505985340?ls=1&mt=8
     
  7. alienator

    alienator Well-Known Member

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    .....or you can just divide the chainring tooth count by the cog tooth count to get a gear ratio. Let's say you're looking at the difference between a 34T chainring on a compact crank set and a 39T chainring on a standard crank set, both used with cassette whose largest cog is 25T. The first combo gives a 1.36 gear ratio, and the second combo gives a 1.56 gear ratio. A lower gear ratio is easier, and in this case, the compact option is [(1.56-1.36)/1.56]*100=12.8% lower. An example of a quasi-typical low gear with a compact crank set is a 34 x 28 combo, which yields a 1.21 gear ratio, 22% and 11% different respectively from the two aforementioned combos. The gear ratio tells you how many times the rear wheel turns with every revolution of the crank set. Some people are more comfortable with developed gear ratios, which are just the gear ratios multiplied by the rear tire circumference. Developed gear ratios tell you how far one revolution of the crank set will move you down or up the road. It doesn't matter whether you use developed ratios or just the plain jane gear ratio: the percent difference is the same either way. For me, it's natural just to think in terms of the gear ratio because at any instantaneous moment, the difference in force required to turn the crank set is the difference in gear ratios. A 12% lower gear requires 12% less force to turn the cranks for a given road condition.
     
  8. oldbobcat

    oldbobcat Well-Known Member

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    Unless you regularly descend steep, long canyons, or you don't leave home without a leadout train, the 53/11 combination will pretty much be a NOP. When I used a compact crank (50-36), I used 11-23 and 11-25 cassettes. My current bike has standard cranks (53-39), so I generally use 12-25 and 12-27 cassettes, which give me pretty much the same set of ratios. Occasionally I use an 11-26 cassette that was given to me, but that 11-tooth cog doesn't get used until I'm trying to a accelerate from 38 mph.

    If you like that cassette and you don't ride like a pro, my recommendation is to keep the compact cranks.
     
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