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  1. #1
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    Moving from triple- to double-crank

    Almost a year ago I decide that I needed to get back on a bike after about 4 years away. At the time I needed the extra gearing of a triple, but 2000 miles later I'm about 25lbs lighter, much more fit and now it's become just a crutch (I hate climbing and if I've got an extra gear, I tend to grab it even if I don't really need it.) After studying the gear ratios, a 53-39 (standard) crankset combined with my existing 12-25 cassette would impose the discipline I lack.

    The question is what all will I need to replace (aside from the crankset itself and assuming I stick with the same bottom bracket type)? I vaguely recall being once told that I should replace the chain when replacing the chainrings. I've also heard that it's a good idea to replace the chain when changing the cassette. From this I gather the rule is: when you change your gears, you should change your chain. Does it work the other way around (change the gears when changing the chain)? How about my dérailleurs? Will the long cage rear be finicky or otherwise annoying (aesthetics aside)?

    Thanks

  2. #2
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    First, and maybe you've already done this, go find the toughest hill you think you may climb when you're tired. Calculate the gear inches for the lowest gear you need to climb that hill at a good cadence, 60 rpm is not good, maybe 75 when climbing. A 39 X 25 combination is 42 gear inches, not very low.

    To convert from triple to double you could simply remove the 30t chainring and adjust front derailleur. If your middle ring is not a 39 you could replace it with a 39 or 38. If you are a purist you can replace the crankset, derailleurs, or even the shifters with double specific components, that's up to you. If you replace the crankset you'll need a new bottom bracket.

    The chain should be replaced based on stretch. A 24 pin length of chain should measure 12 inches. It should be replaced by the time it reaches 12 1/16th inches. Replace the cassette only if a new chain slips. Sometimes a chain will slip simply because the cable is out of adjustment. Road chainrings tend to outlast the rider.

    If you don't like climbing converting from a triple to a double is probably not a good idea.

    Al

  3. #3
    Senior Member Retro Grouch's Avatar
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    This is probably the most frequently asked question on this board.

    If you want your bike to look factory, you will need a new crankset, new bottom bracket, and new front and rear derailleurs. You may also need a new chain and new shifters depending on what you have now and it's condition.

    If you just want to get rid of the granny ring, just take it off and dial in your front derailleur low limit screw. There is the middle ground of installing a new double crankset and bottom bracket, MAYBE a new left shifter. Either way, you won't gain any style points because anybody who cares if your bike has a triple or a double crankset will notice what you have done.

    In your original post you made mention to not careing about esthetics. Other than esthetics, what are you hoping to gain by making this change?

  4. #4
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    Other than esthetics, what are you hoping to gain by making this change?
    I'm hoping to force myself to expend more effort while climbing and hopefully thereby become a stronger climber. Granted, if I had the willpower, I could just choose not to use the extra gearing, but when that extra gear is there I tend to use it. And I wouldn't mind using the easier gear if I were climbing at a higher cadence, but it seems that I have a fixed climbing cadence that seems to stay the same regardless of what gear I'm pushing.

    What got me thinking about this was the other day I was out on my fixed gear (48x16) and I decided to see how far I could get up one of my regular climbs (1.5 mi. w/ 5% avg grade). I managed to get all the way to the top - it wasn't pretty and it wasn't fast, but I was surprised that I could do it at all. So the next day, I'm out on the road bike and climbing that hill and realize both how slowly I'm climbing and how little effort I'm putting into it.

  5. #5
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    Quote Originally Posted by Al1943 View Post

    If you don't like climbing converting from a triple to a double is probably not a good idea.

    Al
    You're right, I guess my real problem is I'm not a naturally good climber and tend to bail to the easiest gear available and I figure if the easiest gear isn't so easy, it will force me to become a better climber. I've been a stronger climber in the past, it took an effort to improve my climbing but it made riding much more fun. I'm willing to entertain other options.

  6. #6
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    Quote Originally Posted by re_buchanan View Post
    I'm willing to entertain other options.
    I tend to think in terms of preserving cartilage. While it is true that mashing big gears can develope bigger muscles, it's not necessarily good for the rest of your body and can be damaging to joints, especially the knees. And you can also develope stronger muscles by spinning more and riding more often.
    I think the best way to improve your climbing ability is to climb more, and you can climb more if you're enjoying it more. Use your cadence meter to find a "compfortable" gear that will let you climb at a good speed without making your joints sore. Let your speed improve with more training. A heart rate monitor could also be a good training aid. Your gear selection should depend mostly on the terrain, how steep, and how long you want to climb. Not everyone will agree but I think it's good to keep the cadence above 80 rpm climbing and above 90 on the flats. Having said that, sometimes I'll climb at 70 as long as my knees don't suffer.
    I don't know you but my impression is that you need to work on your climbing more before you start re-gearing your bike. I went from hating climbing to really enjoying it, especially when I pass people on steep hills that are half my age.

    Al

  7. #7
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    Quote Originally Posted by re_buchanan View Post
    You're right, I guess my real problem is I'm not a naturally good climber and tend to bail to the easiest gear available and I figure if the easiest gear isn't so easy, it will force me to become a better climber. I've been a stronger climber in the past, it took an effort to improve my climbing but it made riding much more fun. I'm willing to entertain other options.
    One option, as RG suggested, is to just lock out the granny ring with fd's the inner limit screw. If you can't get to it, you won't use it. Once you find you don't need it, just unbolt the granny and leave everything else alone. That is, by far, the least expensive method. If "style" is an issue, plan on spending a lot money.

    I'm also a big gear climber and tend to mash gears rather than spin and I live in a very hilly area. That said, I have triples on every bike because there are hills around here I just CAN'T climb in a 42x25 or 42x27. We have a bunch of them at 25% and more and I plain don't weigh enough to turn over the cranks in a big gear on them. Also, I'm lucky that my knees aren't sensitive to the stress of big gears. You may not be so fortunate.

  8. #8
    Senior Member Deanster04's Avatar
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    Agree with the "just lock out the granny ring." I am 64 and use the granny riding the mt roads in Colorado as a "rest" break from the higher gears without stopping. I can tell you from experience that friends who insisted on using the big gears all the time all have knee problems as they age. I have always been a high rev rider and have zero knee problems. I have been riding ten speeds since 1955 and have a lot of examples to choose from.

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