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  1. #1
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    Surly 1x1 with Square Taper

    What square taper bottom bracket length do I have to use for a surly 1x1? The chainstays are so wide even a 73/113 didn't work. I want it to clear the chainstays and give me a chainline that will work with Surly freewheel hubs(54/55ish I think?)

    Thanks!

  2. #2
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    I have a 73/113 in mine and it works fine. I think the spindle length has more to do with what cranks you use.

  3. #3
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    Ok, thanks, but I am not sure I understand. Isn't the 113 the spindle length? I thought 73 was bottom bracket width and then 113 was the overall "spindle" length?

    Thanks.

  4. #4
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    73/109 will put you at 54.5

  5. #5
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    Which cranks do you use? My shimano SQ are smaller at the pedal end than my race face turbine's. I roll an El mariachi (spacious enough for a 2.4 tyre) with 113 and turbine's. I still have room left.

  6. #6
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    Hmmm, I tried 73/113 with a Dimension Cross Crankset and a 39t chainring was rubbing. maybe the Crankset doesn't have much offset?

    Thanks guys.

  7. #7
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    What gearing are you shooting for? You could go to a smaller charinring...
    Sana Cruz 5010v2---Rigid Surly 1x1 650b---CrossCheck---Surly Pacer

  8. #8
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    I was actually planning to run a 42t front with 16 rear. Its really flat here and I mostly ride it on a flat dirt path so I need a higher gear setup. So when the 39t was tight i knew a 42 definitely wouldn't fit. Is there a lot of variation in the amount of "offset" in cranks? I am looking for an all silver crank arm setup(polished), but can't afford anything like the White Industries. Any recommendations?

  9. #9
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    Righty, the chain ring will determine the spindle length, I'm running a 36T Eno thusly the 109 is spot on, a bigger ring and I'd have to go longer. 36/17 works for me but I have to keep a 19T free wheel on hand for hillier ground.

  10. #10
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    Pick up a 73/118 and you should be good.

  11. #11
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    Quote Originally Posted by kbollox
    Righty, the chain ring will determine the spindle length, I'm running a 36T Eno thusly the 109 is spot on, a bigger ring and I'd have to go longer. 36/17 works for me but I have to keep a 19T free wheel on hand for hillier ground.

    Please forgive me for not understanding and thank you for helping out!, but I don't understand how the chain ring determines the spindle length? The spindle length doesn't change whether you have a 36t, 40t, 48t, whatever size chainring, right?

    The spindle length determines the chainline, right?

    Am I missing something?

    Thanks again!

  12. #12
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    Quote Originally Posted by dreed85
    Please forgive me for not understanding and thank you for helping out!, but I don't understand how the chain ring determines the spindle length? The spindle length doesn't change whether you have a 36t, 40t, 48t, whatever size chainring, right?

    The spindle length determines the chainline, right?

    Am I missing something?

    Thanks again!
    A bigger ring could result in the ring hitting the chainstay if the spindle is not long enough.

  13. #13
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    Quote Originally Posted by dumbaSS
    A bigger ring could result in the ring hitting the chainstay if the spindle is not long enough.
    bingo. A 1x1 is a Mtb not a road bike so the chainstays allow less room for the front chainring. With a 73/109 the chain is straight as an arrow with my Surly 135 Disc hub - but 36T is the largest I can go in front.

  14. #14
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    Quote Originally Posted by kbollox
    bingo. A 1x1 is a Mtb not a road bike so the chainstays allow less room for the front chainring. With a 73/109 the chain is straight as an arrow with my Surly 135 Disc hub - but 36T is the largest I can go in front.
    Ok, I see what you are saying. Here is my last confusion. Right now on the 1x1 I have a Deore XT crankset with external bottom bracket. I have the 42t chainring on it and it clears fine and has perfect chainline with my Surly 135mm Free/free hub. If you are saying your chainline is straight but can only fit a 36t that makes me think that if you spaced it out enough to fit a 42t then your chainline would be way off(to the outside).

    I guess I need to just keep playing with it.

    Thanks.

  15. #15
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    Quote Originally Posted by ianick
    Pick up a 73/118 and you should be good.
    zactly... Read it here--Option #3: install a 118mm spindle. In this case, all options worked quite well to correct the chainline.

    link
    We don't need more to be thankful for; we just need to be more thankful.

  16. #16
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    Quote Originally Posted by dreed85
    Ok, I see what you are saying. Here is my last confusion. Right now on the 1x1 I have a Deore XT crankset with external bottom bracket. I have the 42t chainring on it and it clears fine and has perfect chainline with my Surly 135mm Free/free hub. If you are saying your chainline is straight but can only fit a 36t that makes me think that if you spaced it out enough to fit a 42t then your chainline would be way off(to the outside).

    I guess I need to just keep playing with it.

    Thanks.
    Its sounds like your cross crankset is definitely the problem. It is basically a road crankset, and road cranksets are designed to have a narrower chainline given the same spindle length.

  17. #17
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    I believe your crankset will have a Chainline of X with a given spindle width. Your rear hub will also have a specified chainline. If you are using a FW in the rear, you will most likely have to adjust up front (Crankset). You can use a different spindle, chainring spacers, bb spacers etc. If you have a freehub in the rear, you can adjust there. By running a bigger ring up front you add another factor to adjust for. You can probably put in the outisde (big ring) position to help that.

    Check this out. It will help a lot. Lots of information. You can't determine what spindle to use without knowing the chainline of the crankset with a given spindle width.

    http://www.sheldonbrown.com/chainline.html

    GP

  18. #18
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    I got a 1x1 for year round commuting (wanted to run discs) and I needed a 125 mm spindle to use my old 172.5 mm Ultegra cranks. I found a 68mm no-name euro BB that allowed me to internally shim the cartridge on BOTH sides for required clearance and chainline. The crank arms have just over 1/8 inch clearance and the 42t ring about 2 mm. Perfect chainline with my DMR one speed disc hub. Road cranks have lower Q factors and the 1x1 is a mtb, but it works out fine. It helps that I'm a spinner not a stomper.

  19. #19
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    I use a square taper BB FRM 185 mm arm lenght road crankset on my SS, which is designed for 102 -103 mm axle lenght. I'm running a 113 mm XT on a steel SS MTB frame, which has narrower chainstay width than average modern MTB frames. 111 mm would be the absolute minimum. So using a square taper road crank for MTB requires minimum 10 mm, but most often 12-15 mm longer axle.

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