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  1. #1
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    Bottom bracket for SS conversion

    If I want to convert a geared road bike to single speed, how do you adjust the location of the single front chainring to match up with the rear cog (assuming the existing bike had 2 or 3 chainrings to begin with)? Do you need to buy a new bottom bracket that doesn't stick as far out? Can you just place spacers between the crank and the chainring, and use longer bolts?

  2. #2
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    new bottom bracket is best way, spacers might get it close enough--you can get about 3mm I think plus another 3mm by putting the chainring on the inside of the spider, to go to a single ring you will need BMX chainring bolts usually I believe if its a setup where the 3 rings share mounting holes, the originals will be too long

    now if this thing is a freehub, dont worry about it, get a spacer kit and thread on a shimano BMX cog and make that match the chainring chainline

  3. #3
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    you should adjust where the cog is in back not the chainring in front. Ethir space it appropriately on a freehub or respace the axle on a freewheel hub.

  4. #4
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    yeah, i'm making a freewheeling single speed, NOT a fixie. so it sounds like i can keep the existing front BB, just take the chainrings off, place a single speed chainring; then on the rear hub, pull the casette off and use spacers to align the cog? please verify if my understanding is correct.

    if i were to respace the rear axle instead, wouldn't that require me to redish the wheel? if so, it sounds like the spacers-on-the-hub method would be quicker and easier -- probably my best bet as i'm attempting my 1st SS conversion.

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    If is has a cassette hub that is true and you would be silly to respace/dish the rear wheel
    If it is a freewheel hub then you will have to respace and then redish. Don;t worry redishing isn;t as bad as it sounds provided the wheel is in reasonable condition and you can get away with just a spoke wrench. Just go slow and use the brakes/frame as your guide.

  6. #6
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    ok i think i just confused myself. i thought a casette hub was the same thing as a freewheel hub, but apparently not. so if i pick up your typical Schwinn 10-speed from a garage sale, it's gonna have a casette hub on it, correct?

    so freewheel hubs are used for fixies, they don't allow you to coast?

  7. #7
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    no your typical old schwinn will have a freewheel hub.


    On the freewheel hub the freewheel threads on and allos the bike to coast. The standard 5s freewheel can easily be replaced with an ss one but then the hub will have to be respaced on the axle cause there is little room for adjustment on the threading.


    this is a freehub or cassette hub.



    On a freehub(cassette) the coasting mechanism is already built in and surrounded by a splined cylinder. The cassete fits on this cylinder. You can remove the cassette and replace it with a single cog and a bunch of spacers. This allows for plenty of adjustment so you can just fix the chainline with these spacers.

  8. #8
    jack of one or two trades Aeroplane's Avatar
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    Nice photos.
    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.

  9. #9
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    on the 5s freewheel hub, can you remove the casette from the hub, or does the casette and hub come as one module?

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    on a 5 speed the cassette and freewheel are one unit

    You can use existing hub, but the wheel has to be redished and spacers added plus moving the chainring in a few mm's IIRC

  11. #11
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    so to do this, you DO remove the casette from the freewheel??

    p.s. thanks for your patience with my newbie questions.


    Quote Originally Posted by pedex
    on a 5 speed the cassette and freewheel are one unit

    You can use existing hub, but the wheel has to be redished and spacers added plus moving the chainring in a few mm's IIRC

  12. #12
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    no, the cassette and freewheel are ONE unit, unlike a freehub where the cassette is one piece and the hub has the freewheel mechanism built in

    when you take the freewheel cassette off of that 5 speed you will be left with a hub thats ready to have a BMX style freewheel cog screwed right on, problem is the spacing is all wrong, the wheel has to be redished and respaced to fix the chainline

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