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  1. #1
    thanks for not picking me deimos's Avatar
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    Gearing Ratio (nub question)

    I think I may have out of ignorance ordered my Mark V with a 48/14t, or was it 16t? I cant remember and Tony is at the hospital with his wife having a baby so I can't ask right now. Reason is I was talking with an aquaintance who is himself pretty new to fg bikes and I was describing the IRO that I ordered when he said I may have some serious issues with wearing through tires fast with a 48/14 or 16t set up because when i skid or skip I will be wearing the same part of the tire. If this is true I want to email Tony and have him switch it to a more suitable ratio. I live on the east side of SLC Utah and I will be dealing with some hills at times. I am 5'8 and ordered a 53" bike. What are your suggestions?

  2. #2
    jack of one or two trades Aeroplane's Avatar
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    If you have a brake, skid patches aren't anything to worry about. Please tell me you are going to use a brake.
    Quote Originally Posted by Dr Irwin Goldstein
    Men should never ride bicycles. Riding should be banned and outlawed. It is
    the most irrational form of exercise I could ever bring to discussion.

  3. #3
    Senior Member srcurran's Avatar
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    48x14 though is one hell of a ratio, it would only be good for a place that is really flat and you don't start or stop much. You would also have to be a beast to skid with that ratio I would think. I would go for 48x18 if I were you.

    What made you choose 48x14 anywyas?
    flickr I hardly know'r

  4. #4
    thanks for not picking me deimos's Avatar
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    If you have a brake, skid patches aren't anything to worry about. Please tell me you are going to use a brake.
    ya - of coarse

    but if i am skiding/skipping when at all possible am i gonna be tearing through tires like mad?

    I would go for 48x18 if I were you.

    What made you choose 48x14 anywyas?
    oh hell i don't know - now that i've been thinking about it all night i think i actually more likely chose 16t - however, if 18t is gonna be better for me then i better email IRO and get that changed asap - thanks for the advice, i feel like such a motard for asking these things but i guess thats just what i have to go through untill i am higher up on the learning curve =P

  5. #5
    don't pedal backwards... MacG's Avatar
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    48/17 is where it's at for me. Try this:

    http://www.basementfreaks.com/member...get=74&diaid=2

    You'll get skid patches and can get a better idea of what your gearing will do for you at different cadences and speeds.
    from Minneapolis, with bike love

  6. #6
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    Karl's gear inch spreadsheet

    Pardon my question but that chart looks wonderfully official & quantitative but I'm unable to understand what it actually means. Would the wise ones kindly point towards documents/books that would help me understand? What does the skid marking from this thread have to do with? Burning rubber on a really fast bike? Is this off-roading or some form of cycling that is simply unknown to me? I'm not even sure why a 14, 17 or 18 makes a difference in terms of braking...is this sheer velocity and momentum achieved vs the pressure required to apply the brakes?

    This is gonna be my last question since it appears that I am woefully unprepared to even READ this messages...

  7. #7
    Senior Member srcurran's Avatar
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    Quote Originally Posted by centexwoody
    Pardon my question but that chart looks wonderfully official & quantitative but I'm unable to understand what it actually means. Would the wise ones kindly point towards documents/books that would help me understand? What does the skid marking from this thread have to do with? Burning rubber on a really fast bike? Is this off-roading or some form of cycling that is simply unknown to me? I'm not even sure why a 14, 17 or 18 makes a difference in terms of braking...is this sheer velocity and momentum achieved vs the pressure required to apply the brakes?

    This is gonna be my last question since it appears that I am woefully unprepared to even READ this messages...
    The top chart is a list of skid patches. Most people have there cranks in the same position every time they skid. If you have a ratio of 48x16 which is a 3x1 then one crank rotation will create three full rotations on the wheel (and it will end up with the same part of the tire facing down).

    If you have a 48x17 ratio the two numbers are relativly prime which means you can't break it down further than 48x17 which means you have 17 skid patches (or 17 different positions that the tire would be relative to your cranks).

    If you have 1 skid patch you can burn through your tire in one position and end up with a hole in it.

    The bottom is straight ratios and shows you that 42x14 will feel the same as 48x16. And if you know that you have a ratio of 3.0 and you want to move down to 48x18 you can also see that 43x16 is the same ratio. You can look at the chart based off of what you have now/know, and use it to help you find a better ratio. This is similar to gear inches, just a different measurement.

    Hope that helps.
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  8. #8
    aka mattio queerpunk's Avatar
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    Quote Originally Posted by deimos
    ya - of coarse

    but if i am skiding/skipping when at all possible am i gonna be tearing through tires like mad?
    if you're skiding and skipping when at all possible, you're not gonna get anywhere very fast.

    anyway, it depends on the tire, doesn't it? some will last nigh on forever. others, not so much. cheapo nashbar kevlar belted ones lasted me about two months (rear tire that is. front is goin' strong!). a schwalbe kevlar belted tire lasted me five or six months with lots of skidding. then i skid through to the kevlar and retired it (get it?).

    of course the smart thing to do would be not to skid unless you really need to but sometimes i feel the need to throw my torso over the bars like i'm superkid and just drag my wheel around town, cause it's sort of fun.
    the hipster myth.

    i practice vagabondery.

  9. #9
    Senior Member
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    Quote Originally Posted by centexwoody
    Is this off-roading or some form of cycling that is simply unknown to me?
    What srcurran said, but also you should note that these are fixed gear bicycles we are talking about. Fixed gear means that when the wheel moves, the pedal moves. Forward or backwards, no coasting. Like a tricycle. Most fixed gear riders ride without a rear brake (Some even ride without a front), because by resisting the movement of the pedals they can slow down the rear wheel. An extension of resisting the pedals is locking them up, causing a skid. That's why the skid patches come into play.


    Check http://sheldonbrown.com/fixed/ for some more fixed gear information.

  10. #10
    Geek Extraordinaire sivat's Avatar
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    Another thing to keep in mind is that the ratio isn't forever. New cogs aren't too expensive, and they're not all that hard to change. If you end up not liking what you get, $30 will get you a new cog. I would say go with 48/17. Tons of skid patches, and I ride a 2.8 ratio in an area with only small hills and it seems to work well.
    I'd rather have a bottle in front of me than a frontal lobotomy.

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  11. #11
    YOU ARE NOW TUNED IN No_Minkah's Avatar
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    Are you sure the chainring is 48 tooth? The stock IRO chainring is 46.

  12. #12
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    ah, I get it now about 'fixed gear'

    thanks to srcurran & gorn - my uncle used to ride what I now recognize as a fixed gear bike with NO brakes. He commuted to the television station in Fort Worth up & down hills. The few times I rode his bike (with his small smile of permission...) it was pretty hairy or at least completely different than any other bike I've ever ridden.

    the gearing issue deserves some serious study since my Giant MTB is not serving me well for a recreational road bike in terms of gearing satisfaction & now I know why.

    thanks,

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