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Thread: gear sizes

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    gear sizes

    can someone point me to where i can read about bike gear sizes ? thx Cuz

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    Senior Member Jim Kukula's Avatar
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    Sheldon Brown is always a good place to start:

    http://sheldonbrown.com/gloss_g.html#gear

    or wikipedia:

    http://en.wikipedia.org/wiki/Bicycle_gearing

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    Senior Member wahoonc's Avatar
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    I will second Sheldon Brown. What specifically do you want to know? Gearing is a huge topic. I use different gearing ranges for different types of bikes. Different bikes have different numbers and ranges. I have everything from single speeds up to 21 gears, new bikes can have as many as 28 or 30.

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    Quote Originally Posted by wahoonc View Post
    I will second Sheldon Brown. What specifically do you want to know? Gearing is a huge topic. I use different gearing ranges for different types of bikes. Different bikes have different numbers and ranges. I have everything from single speeds up to 21 gears, new bikes can have as many as 28 or 30.

    Aaron
    looking to get a folding bike, one of them is geared from 33 to 66.... i'm wondering how that will work for me. i read the wikipedia link and wonder if 66 isn't high enough. But i guess that can be remedied

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    Senior Member Jim Kukula's Avatar
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    33 to 66 is not a very deluxe gear range but it sounds practical actually in a bare bones sort of way. 66 ought to be fine for riding on the flat and 33 is decent for going up hills. You won't have anything for downhill but that is the least important gear anyway. Mostly I like a good downhill gear so I can pick up some momentum to help carry me a ways up the next climb!

    If the price is right, a 33 to 66 gearing will get you across town OK.

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    Quote Originally Posted by cuzzinit View Post
    looking to get a folding bike, one of them is geared from 33 to 66.... i'm wondering how that will work for me. i read the wikipedia link and wonder if 66 isn't high enough. But i guess that can be remedied
    Hi,

    I'm an old duffer riding a 33 to 66 folding bike and can tell you
    66 isn't enough for pounding downhill or for a big tailwind.

    I also have a 40 to 100 road bike for comparison.

    If your young and fit 33 to 66 will be limiting. I've done 33mph on
    my folder downhill with the wind behind me, but stopped pedaling
    to any useful effect around 20mph, that is a high cadence for me.

    For me the gearing range is about right, assuming you don't
    want to hammer it downhill or with tailwinds. 18mph is about
    my consistent limit mild downhills or some tailwind on the flat.

    I can go quite a bit faster on my road bike, not that it matters.

    Initially for me I struggled uphill and into headwinds with the
    lower gears, but I'm an old duffer, and now they are fine.

    rgds, sreten.
    Last edited by sreten; 05-28-13 at 09:42 PM.

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    Hi,

    FWIW I can go up hills easier on my 40" to 100" road bike
    than I can on my 33" to 66" folder, gear inches don't tell
    you everything about the effective gearing of a bike.

    The gearing for a typical 6 speed cheap folder is low for
    16" wheels and about right when used with 20" wheels.
    Usually a 14, 16, 18, 21, 24 and 28 freewheel on the back.

    rgds, sreten.

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    coprolite fietsbob's Avatar
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    Ratio (tooth count numbers) F:R x wheel diameter, calculate circumference X wheel RPM & you got speed.

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    Thx that's what i wanted to know

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    Senior Member Retro Grouch's Avatar
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    Quote Originally Posted by cuzzinit View Post
    . i'm wondering how that will work for me.
    You're asking a question that only you can answer.

    None of us have to ride that particular bike over your roads while using your body. The bike comes with gears the manufacturer thinks will work for most people. You aren't most people, you're you. Get the bike and ride it around for awhile. It'll tell you if you need higher or lower gears.

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    Quote Originally Posted by cuzzinit View Post
    But i guess that can be remedied
    Hi,

    Not easily or cheaply. The rear 6 speed is pretty much a standard 14 to 28
    freewheel, and the 14 to 34 megarange won't work with the rear derailleur,
    though I assume your after more than 66", not lower than 33".

    I've looked and haven't found many other sized 6 speed freewheels.
    I'm sure they are out there but just not very common / stocked.
    13t is the smallest I've found and not cheap at all.

    Changing the crankset to more teeth is expensive for the minor benefit.

    rgds, sreten.

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    Quote Originally Posted by sreten View Post
    FWIW I can go up hills easier on my 40" to 100" road bike
    than I can on my 33" to 66" folder, gear inches don't tell
    you everything about the effective gearing of a bike.
    If the bikes are tuned and fit the same way, it should tell most of the story. Admittedly, for many folding bikes this probably isn't the case.

    That suggests that either your position on your folding bike isn't as good as that on your road bike (meaning you can more easily generate power on your road bike) or some other inefficiency in your folding bike (tires, drive chain). At hill climbing speeds, aerodynamics shouldn't be playing a large effect.

    The real point of this is that this doesn't have to be the case with folding bicycles - they can be (almost) as performant as full size bicycles.


    Quote Originally Posted by sreten View Post
    Not easily or cheaply. The rear 6 speed is pretty much a standard 14 to 28
    freewheel, and the 14 to 34 megarange won't work with the rear derailleur,
    though I assume your after more than 66", not lower than 33".

    I've looked and haven't found many other sized 6 speed freewheels.
    I'm sure they are out there but just not very common / be stocked.
    13t is the smallest I've found and not cheap at all.

    Changing the crankset to more teeth is expensive for the minor benefit.
    This is basically correct. Long-story-short, if you know you are going to want to change the gearing, you are probably better off buying a nicer folding bike.
    Last edited by cplager; 05-30-13 at 06:04 PM.
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    IMHO - for a non racing utility and pleasure rider, a 1x9 set up bike with 12-36 cassette and 44 t chainring with a 32/622 tire provides a gear in range of 33-99 (in hilly areas substitute a 39 t chain ring). This range provides a pragmatic and reliable useful range.
    ride long & prosper

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