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    • CommentAuthorcqbfix
    • CommentTimeDec 27th 2009
     
    ok,I was wondering. Im buying new cranks, and want to know about the setup. what is the difference of the higher an the lower number for chainring. what would be the description of like a 47 chainring and then what would be the description for like a 39 chainring, or something low.
    • CommentAuthorgreg
    • CommentTimeDec 27th 2009
     
    I can has troll?

    Higher ring tooth numbers mean a higher/tougher gear to peddle
    • CommentAuthorcqbfix
    • CommentTimeDec 27th 2009
     
    IM NO TROLL!!!!!!
    • CommentAuthorcqbfix
    • CommentTimeDec 27th 2009
     
    and another thing... is 47 good? or should i go with 46 or 48.. i want to be able to go really fast but also be able to skid fairly easy
    • CommentAuthorheadydude
    • CommentTimeDec 27th 2009
     
    have you done this before or are you just starting out?
  1.  
    How many teeth is your cog? 48 is getting twoards the higher end of the spectrum. Most people will run something like 42/16 or 46/18, stuff like that. It just depends on how strong you are, where you ride, etc. If you are big, you can run a higher gearing, but for me, I'm scrawny so I have to run a smaller gear and spin it out.
  2.  
    OK, here's the deal on gear ratios.

    You, as a cyclist, have a particular frequency, called "cadence", at which you can spin your legs. If you're new to biking, that's probably something like 50 - 60 rpm. Professional cyclists are around 80 - 110rpm. It's really hard to pedal that fast. I can only do 100 rpm for a few seconds and have a hard time staying at 90 for very long at all.

    The faster you go, the less pressure there is at one time, and the better it is on your knees.

    So I think the way to choose a gear is to figure out your cadence, then figure out how fast you can go at that cadence. When you can get from point A to B at 90 - 100 rpm, get a bigger ratio.

    With lots of gears on a bike, that's not much of a decision. It's pretty easy. You just switch gears. But with one, it's hard to figure out. Hey, no one said it was a practical way for a beginner to build a bike.
    • CommentAuthorcqbfix
    • CommentTimeDec 27th 2009
     
    well i am small. i just want to keep up with my friends and not get worn out so easily. and they go really fast! but I will either do 46 or 47. what do you guys think? I just want input...
    • CommentAuthorCeya
    • CommentTimeDec 27th 2009
     
    To keep up with them depends on you and your fitness.

    bike/gears/parts is only half of the solution.

    start with around 48 x 17 or 46 x16.

    S/F,
    CEYA!
    • CommentAuthorSkidMark
    • CommentTimeDec 27th 2009 edited
     
    It depends on what your rear cog is.

    Also you will get more skid patches with chainrings/cogs that are not divisible.

  3.  
    Every post you make seems like a complete joke. Between your Leader bikes stuff, Aerospokes and HED wheels, Riser bars, skidding up tires, mashing on pedals and blah blah blah....this thread now fits in nicely with the rest you've started. Congrats.

    Anyway...make sure you buy Sugino Grand Mighty cranks, because nothing else will be strong enough to handle the mashing you will be doing around your school. They are gold in color also.
    • CommentAuthorwes m.
    • CommentTimeDec 27th 2009 edited
     
    At least this kid knows that he doesnt know anything. Thats more than can be said for most high schoolers. His threads have a pre-first-disappearance lickedwicked quality.

    Ok, back to the point. Gear inches in the low 70's are a common starting point. Use this:

    http://www.sheldonbrown.com/gears/

    Set the wheel size to 700c x 23-28ish. Set the gear units to gear inches. Type in random chainring and cassette (or cog in this case) sizes. Figure out how it works.

    Just get a 46 or 47 tooth ring and a 17 tooth cog and call it a day.

    p.s. why dont you just ask your "really fast" friends what ratio they ride?
  4.  
    CQB, you're not reading the helpful posts. We can't decide on a number for you. Figure out how fast you can pedal. Get gears that give you the speed you want at that pedalage. If they don't exist, it's because you need to train your legs.
  5.  
    46/17 for the first crankset you buy, and by the time you upgrade, you'll be big and strong enough to get a 49/17 : )
  6.  
    Give the guy a break he's just trying to learn something.
    The idea is the greater the numerical difference between the chainring and the cog the faster your top speed or the less likely to spin out. That being said, if you have high gear ration (large numerical difference) going up hills will be harder, you'll be less likely to spin out
    while going downhills and you'll have faster top speed but lower acceleration. The lower the gear ratio (smaller numerical value) Up hills are easier, down hills you'll be more likely to spin out and the on the flats you'll have faster acceleration but slower top speed. The thing is to learn to skid it tends to be a fair bit easier on low gear ratio and work your way up. Its really a balance of what you're comfortable with, I agree with GOBSTOPTODROP you should maybe start low and work your way up. I rock a 49/16; I went with the 16 because as I progressed it provided me with a greater range of ratio. I hope this was helpful.
    • CommentAuthorSkidMark
    • CommentTimeDec 28th 2009
     
    68 to 72 gear inches, unless the city you live in is dead flat and there is no traffic.
    • CommentAuthorTJW
    • CommentTimeDec 29th 2009
     
    honestly... you should ride your bike for a while, before buying new cranks.
 
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