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  1. #1
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    Compact 50/34 vs 52/39 Crank

    Any recommendations before choosing a compact 50/34 over a 52/39 crankset? I've always ridden a 52/39 crank with a 12/23 cassette. I'm a taller rider, average weight. I race road and do alot of climbing but also do a few triathlons per season. I've looked into the gearing ratios between both cranks and variations of cassettes. Are there any general rules advantages/disadvantages over choosing one crank over another? I hear the new thing is getting a compact crank but does it really matter?

    Thanks for any input...

  2. #2
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    the disadvantages...

    Include the loss of top gear and one more cog to shift after every chainring shift, to make up for the large jump between the chainrings. Compacts are more often beneficial for the increasing number of older or less fit riders, who find that a 12-27 shimano cassette doesn't provide enough low gearing and don't want to change to a triple.

    A 50/34 takes 6% from the top gear ratio and increases the low by 13%, for a net increase in range of 7%, which is slightly less than an average 8% 1-cog change.

    You could of course, change to an 11-21 cassette and gain a tiny 3% on the top gear and reduce your low gear to the same as a 39/24 (also a small 4.4%). The cog shifting penalty remains the same.

  3. #3
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    Other disadvantages

    Quote Originally Posted by Spicoli
    Any recommendations before choosing a compact 50/34 over a 52/39 crankset? I've always ridden a 52/39 crank with a 12/23 cassette. I'm a taller rider, average weight. I race road and do alot of climbing but also do a few triathlons per season. I've looked into the gearing ratios between both cranks and variations of cassettes. Are there any general rules advantages/disadvantages over choosing one crank over another? I hear the new thing is getting a compact crank but does it really matter?
    Unless you need the lower gears, there's not much point. If you downsize your chain rings and your cassette, then the net result is the same gears and faster chain and cog wear with a little less weight. Your choice.

  4. #4
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    Quote Originally Posted by C-40
    Compacts are more often beneficial for the increasing number of older or less fit riders...
    Like this loser.

    Attachment 52110


    I'll gladly include myself in that "older and less fit" category, and don't consider it a large loss to spin out at 39 instead of 40 mph on the top end. On the low end, I occasionally ride steeps that a 39X25 (23 in your case) won't go up regardless of fitness - the leverage available vs weight simply won't math out.

    Amongst the disadvantages listed, one advantage is that some prefer the gear spreads that a closer-ratio cassette than the 12/29 often recommended as an alternative affords. Having to double-tap the rear for a front shift is a bother, but since the crossover is in the 16mph range, it doesn't seem to matter all that much. Curiously, since that's a speed range that a lot of "older, less fit" riders would spend their time, that would make compacts less recommended (as compared to a triple) for that group.

    My take is that their value depends on how and where you ride. There's a good argument for use on a lightweight climbing bike, arguments against for a flatland, moderate speed bike. TT/Tri rigs would tend not to benefit. Really hard pitches or less fitness might be better suited to a triple. Fast rec riders are more likely to be happy with them than top-class racers, where that last click in top end could possibly make a difference.

    There's a tendency to dismiss them as nothing but a marketing play by the manufacturers. Since nearly everyone makes them and the majors were among the last on board, that argument is economically iffy. Marketing-driven changes tend to come from the majors and trickle downmarket. Customer-driven changes tend to start in the niches and bubble up to the majors. As a rule, customer-driven changes tend to be more 'real', because folks tend to demand what they've seen work for others. That doesn't rule out faddishness, but fads tend to hang to a particular vendor, which doesn't seem the case here. Time will tell.

    If you've been satisfied with 52/39x12-23, it doesn't seem like you're in one of the narrowish slots where they make sense.
    Last edited by danl1; 04-07-2009 at 05:04 PM.
    A good habit is as hard to break as a bad one..

  5. #5
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    I switched to a FSA carbon pro 50/34 & use a 11/23 cassette.
    Been running it since Oct 05 & like it a lot.
    My 53/11 gives me a 122" gear which is larger than a 53/12 119" gear
    My 34/23 gives me a 39.9" while a 39/25 gives a 42.1"
    So I have a lower low & a higher high that a 53/39 running a 12/25 cassette. All my rides have considerable climbs & of course descents so it works well for me.
    I dont notice any hassle of an extra shift when changing chainrings because .....well I don't ;) I mean when I shift from the large ring to the small or vice versa I am most likely going to change one or two gears in the back anyway. Plus with ergo it is a mindless task anyway.

    As for it being for older or less fit riders? I got the idea from Tyler Hamilton when he won Liege Baston Liege on a compact.
    Since you said you do a lot of climbing I would give it a try & see what you think.

  6. #6
    LBK
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    I'll cut the BS.....

    Just get the regular crank.

  7. #7
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    Tyler's 52/36 compact

    Everyones likes to take things out of context. Sure there are RARE occasions when a pro may use a compact, like when Tyler broke his collerbone and needed a bit lower gearing for the mountains. The 36T is like adding one cog lower. Don't know if he coupled it with a 12-25 or 12-27, but he didn't use a 50/34 according ot the reports I read.

    I don't think you'll see many pros using a compact on a regular basis..

    If you like to note extremes, Roberto Heras also uses a triple on some stages, so I guess my carbon triple crank is a hot pro setup too?
    Last edited by C-40; 05-01-2006 at 03:26 PM.

  8. #8
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    Well I dont buy based on Pro usage but I did get the idea to try when I first read about them. That was as I said during a report on Tyler.
    I think most here are just looking for a response from those who used a product & what they thought about them.
    I use it I like it......nothing more ;)

  9. #9
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    compact crank gearing

    I use a 36-50 compact on one of my bikes with a 12-27 and it works just fine with none of the shifting problems associated with compact setups. Its a D/A 10 and Im not that interested in topend speed I run in the 36 alot and have the full use of the rear casette. Im using an FSA crank and if I have to go lower I will use a 34/46 I dont like the big jump of the 34-50. Im not giving advice but relating my experiences, I really like the compact setup its the way to go.

    Chris V
    Fort Worth

  10. #10
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    well...

    I rode a 53/39 with a 12-21 (9 speed) on rolling terrain until 10 speed came out when I was only 47. At that point I switched to a 12-25, which provided what seemed like an incrediblely low 39/25. With that low of gear, I could choose to sit and piddle up a hill or stand in a 39/19 or 39/21 as I had for years.

    The occasions when a pro would have the need for a compact are few and far between. Only the steepest of mountain stages might prompt the use of a compact. I'd bet most use an 11-21 or 11-23 with a 53/39 the majority of the time and on a rare occasion use a 12-25. The shimano equipped guys can even opt for a 12-27, but the campy guys get left a bit short if a 39/25 isn't low enough. A 53/13 top gear is rarely an option for a pro and a 50/12 is not much better.

    FWIW, at nearly 53 year of age, I get by fine with a 39/23 low as long as I'm not in the mountains. If I'm really tired and need a 39/25 for very long, I slip into the 28T ring and use the 17 or 19 cog, rather that use the extreme 39/25 chainline on my triple.

  11. #11
    Team American Classic
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    Just to throw a wrench into it.....

    I like the compact crank, but found something even better....junior gearing! I've tried the 13-26 and 14-25 and I like them! How much do you really need an 11 or 12 anyway? Around the same price as a normal cassette, but gives you really tight gears that make controlling cadence very easy....

    The Flash!

  12. #12
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    how about this...

    I'm was debating the same thing myself, only some of the members here have
    suggested(rightly) that i just get a smaller chainring and bump the cassette a bit:

    current:
    1991 Shimano Dura Ace - 53/39 x 13-23

    so i'm gonna keep my current crank and get:
    1 - salsa 38t/130bcd inner ring
    2 - FSA 50t/130bcd big ring
    3 - shimano hg-50 12-25

    all for a bit less than $100 new(bikeman.com). this is considerably less
    expensive than a new crank/BB _and_ wider range cassette(and much less work ;-)
    anyway, if i find that i still need more bottom end, i can always get a 26t or 28t
    single cog to add to the cassette for a bail-out gear for the hills.

    when i build my next bike i will likely spec it with a compact crank, and know that
    i can get extra chainrings for flexibility; at 110bcd, you have a few more options,
    primarily at the bottom end:
    Outer Sizes - 46, 48, 50, 52, 53, 54, 55T
    Inner Sizes - 34, 36, 38, 39, 42, 44T
    Improving on self-torture for more than 3.6^2 years.

  13. #13
    LBK
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    Hmmm....

    Quote Originally Posted by flying
    Well I dont buy based on Pro usage but I did get the idea to try when I first read about them. That was as I said during a report on Tyler.
    I think most here are just looking for a response from those who used a product & what they thought about them.
    I use it I like it......nothing more ;)
    Sounds like a typical placebo effect. Do your calculation, there isn't much benefit as what people said. Also, I think you DID buy your crank based on Pro usage.

  14. #14
    RoadBikeReview Member
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    Quote Originally Posted by LBK
    Sounds like a typical placebo effect. Do your calculation, there isn't much benefit as what people said. Also, I think you DID buy your crank based on Pro usage.
    What is it with this site anyway?
    Pretty odd that if you have an opinion here it is almost always challenged.
    No I base my choice on the fact that all my rides have at least 4000' of climbing with the option to go to 7000' or 9000'
    Grades can reach 20% although I am not there too often these days.
    But still back to the original problem.......Is this truely road rage review or what?
    It is ok to have an opinion trust me.
    PS: In the end it is all just gear inches. Does it matter how you get it?
    I prefer the closer ratio of running the 11/23 but still have the gears I need for climbing & descending.
    If you think your stronger or faster because you use a 53/39 your mistaken. Gear inches are gear inches.
    I have all the gears you have with a 53/39 & a 12/25 only mine are closer & have a higher high & a lower low
    at less weight. Use what you like & I will do the same. ;)
    Last edited by flying; 05-01-2006 at 07:25 PM.

  15. #15
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    Not all riders use the same spin

    When using a 53-39 and as low as a 27 in the back, I, and all the racers in the group, have to stand on steep grades to keep enough speed up in the high gears. Standing is not an efficient technique for a 220 pounder for long perioods of time. So, I switched to a compact FSA 34-50. Now, though not considerably lower, I run a 25 cog in the rear and sit and turn cranks due to thereduced load. I feel a hell of alot better at the top and climb at the same speed through a slightly higher cadence. In flatter races, the 11-23 will give me all the high gear I need.

    Acclerated wear? The fact that each tooth of a 50 T will get used 5.7% more often than a 53 and each tooth on a 34 12.8% more than a 39 will not keep me up at night.

    When I no longer use the 34-25 combo, or even 34-23 combo for climbing, I will put a standard crank back on the bike, but until then the compact is a good fit.

  16. #16
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    Can someone explain how the front deraileur comes into play?

    It is my understanding that you can't have more than a 14 tooth difference between your front cogs for the deraileur to work properly. So, 53-39 is just right. Yet, the compact crank (most) is 50-34, a 16 tooth difference. My friend is running this compact crank setup with the same deraileur that was used for his 53-39.

    I have often thought of experimenting with a 54-38 setup, but never explored it much because of the front deraileur limit. I am 6'5" 220, and find myself needing help on uphills and spinning on downhills.

    edit: my 9-speed rear varies, i have 11-21, 11-28, and 12-25

  17. #17
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    Quote Originally Posted by Bianco
    Can someone explain how the front deraileur comes into play?

    It is my understanding that you can't have more than a 14 tooth difference between your front cogs for the deraileur to work properly. So, 53-39 is just right. Yet, the compact crank (most) is 50-34, a 16 tooth difference. My friend is running this compact crank setup with the same deraileur that was used for his 53-39...
    With DA10 and 53-39, the front was heaven. Running compact 50-34, it works OK but not like before. Dropping a chain - going big to small - has happened a few times and - small to big - is not as smooth and crisp.

    I want to work on keeping my cadence up, though, so I am staying with it; sacrificing heaven for spin =)

  18. #18
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    Wear points

    Quote Originally Posted by El_Toro
    Acclerated wear? The fact that each tooth of a 50 T will get used 5.7% more often than a 53 and each tooth on a 34 12.8% more than a 39 will not keep me up at night.
    The chain ring wear is not the main point - it's all about cassette wear. You don't have many teeth engaged back there when you're on the smaller cogs. These cogs therefore wear faster, which wears the chain faster, which then does wear the chain rings faster. My point is that if the only result of having a compact is shrinking both the chain rings and the cogs, then all you get is a few grams shaved and increased wear on the drive train. If you feel that is a good tradeoff, then get the compact. If you need a compact for lower gears, then it's a good approach.

  19. #19
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    I don't think it's really about having fewer teeth engaged. At any moment, there's only about three teeth that are carrying the load, no matter the cog count (unless chains are seen as elastic) . The problem is that a wheel (or a crankset) is essentially an integrated series of third-class levers, and the smaller gears place more strain on their load point. At a given pedal torque and gear-inch, a chain on a smaller set will suffer more tension than a larger set. Chain wear occurs first, in the form of 'stretch' (really internal wear). That eventually causes the strain to be taken up on the first tooth at the takeoff point, since there's now some slack back to the next tooth. That excess force causes excess tooth wear, until the pitch of the cog approximates the new pitch of the chain. Smaller cogs see it first, because the leverage means they are under more strain.

    Replace your chains frequently, and your cogset will last a long, long time. Replace your cogs frequently, and your chains will wear pretty much as fast as they ever did.

    At least that's how I see it, and Sheldon seems to agree with me.
    http://www.sheldonbrown.com/chains.html
    Either way, it's a factor in the compact discussion that I hadn't considered before.
    A good habit is as hard to break as a bad one..

  20. #20
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    Additional sprocket wear mechanisms

    Quote Originally Posted by danl1
    I don't think it's really about having fewer teeth engaged. At any moment, there's only about three teeth that are carrying the load, no matter the cog count (unless chains are seen as elastic) . The problem is that a wheel (or a crankset) is essentially an integrated series of third-class levers, and the smaller gears place more strain on their load point. At a given pedal torque and gear-inch, a chain on a smaller set will suffer more tension than a larger set. Chain wear occurs first, in the form of 'stretch' (really internal wear). That eventually causes the strain to be taken up on the first tooth at the takeoff point, since there's now some slack back to the next tooth. That excess force causes excess tooth wear, until the pitch of the cog approximates the new pitch of the chain. Smaller cogs see it first, because the leverage means they are under more strain.
    There's two additional factors at play as well. On a smaller sprocket, the chain takes a greater bend from tooth to tooth, so there is less transmission of load beyond the first tooth or two, concentrating the load on fewer teeth, which increases wear of smaller sprockets. Also, for the same size chainrings and cadence, smaller rear sprockets turn faster, so there are more engagements/disengagements per unit time on smaller sprockets, and hence faster chain wear (most wear occurs as the chain engages or disengages). With the same chainring, cadence and pedal force (torque), a 13 tooth sprocket turns twice as fast as a 26 tooth sprocket, and that alone will double the wear.

    Another side note: Sprockets do not actually change pitch when the wear - pitch is a function of the angle and diameter of the teeth, and sprockets don't change diameter or angles between teeth. However, when running a worn chain on a sprocket, the effective pitch of the engagement may increase. A worn chain has a longer pitch than a new chain, and when a worn chain engages a sprocket the chain may ride up on the sprocket teeth to try to match the longer pitch of the chain to the shorter pitch of the sprocket teeth.

  21. #21
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    "With the same chainring, cadence and pedal force (torque), a 13 tooth sprocket turns twice as fast as a 26 tooth sprocket, and that alone will double the wear."

    And the speed will be doubled too. I don't think that is the analogy you were looking for.

    Jim
    Jim Purdy - Mansfield, TX

  22. #22
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    Speeds, gearing and terrain

    Quote Originally Posted by JimP
    "With the same chainring, cadence and pedal force (torque), a 13 tooth sprocket turns twice as fast as a 26 tooth sprocket, and that alone will double the wear."

    And the speed will be doubled too. I don't think that is the analogy you were looking for.
    Sure it is. Since cyclists ride up and down hills as well as on flat ground, a rider may be going a wide range of speeds and use a wide range of gearing at the same power. If a rider pedals at 90 rpm and 200 Watts for 2 hours, first 1 hour on flat ground in a 42x13, and then 1 hour uphill in a 42x26, the chain would move the same speed and at the same tension, but the 13 tooth sprocket would get more wear.

  23. #23
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    Quote Originally Posted by Bianco
    Can someone explain how the front deraileur comes into play?

    It is my understanding that you can't have more than a 14 tooth difference between your front cogs for the deraileur to work properly.
    Manufacturers' stated derailleur "limits" are conservative.

    Al

  24. #24
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    I think we need a poll to see how many of us are pros. Everyone uses what a pro does for a reason to do or not do something. Seeing as how probably none of us are pro, then why even bring it up. If I were a pro I sure wouldn't be getting advice from anyone here.

    I went on a ride today with a 50/34 compact today for the first time. The only negative I found was the chain rubs the big ring while you are in the small ring up front if you are in the outer 2-3 cogs in the rear. Of course I never run the outer cog anyway, so that doesn't matter. The only reason I like the compact is that I can normally run an 11-23, then if I am doing a long ride with lots of climbing I can put on the 12-27 and have a really low gear without having to chaing to a triple. Of course I guess I could always get a rear cassette with 28 or 29 cog.

    Also, compact cranksets are not always lighter. The Pulsion 50/34 is actually 20g heavier than the 53/39.

  25. #25
    JBF
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    The Flash is onto something here !!

    Quote Originally Posted by The Flash
    Just to throw a wrench into it.....

    I like the compact crank, but found something even better....junior gearing! I've tried the 13-26 and 14-25 and I like them! How much do you really need an 11 or 12 anyway? Around the same price as a normal cassette, but gives you really tight gears that make controlling cadence very easy....

    The Flash!

    I AGREE !!!! This is the alternative nobody seems to want to hear. The issue for most of us (all you pros out there are excluded) is running out of gears at the low end, not spinning out at the top end. I run a 38/52 up front with a 13-23 or 13-26 (9-speed) in the rear. The 13-23 is almost a straight block so the perfect gear is always at hand and shifting between the rings is very crisp. Its pretty tight gearing with the 13-26 as well, and switching to 10-speed it could be just as tightly spaced as the 13-23. How low or how high your range is only part of the equation. Having big gaps in between drives me crazy.

    Having said this, I am reading this thread because I am intrigued by the compacts but not convinced ...

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