Karate Monkey single speed chain tension question- Mtbr.com
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  1. #1
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    Karate Monkey single speed chain tension question

    I bought a karate monkey frameset and am building it up as a single speed. I have a SRAM DUB crankset with a 32 tooth ring on it, and I’m using a custom built DT Swiss 12x142 rear wheel (the Gnot-Boost dropouts work great), I’m gonna start off with a 20 tooth Niner single speed cog.

    Anyways, my question is: how do I properly tension the chain with the horizontal dropouts? It’s sort of tough to pull the wheel back in the dropouts and tighten the axle down, while keeping the wheel straight in the frame and keeping the chain tension good. I’m also worried about the wheel slipping forward in the dropouts under heavy load.

    Do I need the Surly Tuggnuts or can I just pull the wheel back and tighten it super right to hold it in place?

    Also, how tight does the chain need to be? This is my first single speed bike without a derailleur mounted chain tensioner, so I don’t know how tight to make the chain so it runs properly.

    Thank you,

    John

  2. #2
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    Despite how heavy they are, I’m a fan of the Surly Tugnuts. I ran one on each side of my Krampus and always had perfect alignment and zero wheel slippage.

  3. #3
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    Thanks. Anyone else? I really don’t want to spend the $60 for two Surly Tuggnuts, but I will if they’re necessary.

  4. #4
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    you need a Snugnut, not a Tugnut.

    I put a single Snugnut on the drive side of my frame and it works fine. use the drive side Snugnut to get the chain close to the tension you want, then straighten the wheel in the frame with one hand and tighten the axle with your other hand. I find that you don't want to make the chain tight first, because when you straighten the wheel, it over-tightens the chain. if this sounds complicated, trust me—it's not. if you can tie your own shoes, this is easier.

    I also learned to walk my axle into position on a bike with track ends from decades of riding BMX, so maybe this is not an intuitive to some folks as it was for me.

    the thru axle on that frame is supposed to be torqued to 16Nm with grease on the bolt. use a damn torque wrench! that's a lot of torque. both ends of the Surly thru-axle have knurled surfaces that bite into the frame pretty hard. I really don't need a Snugnut on my frame because I don't think the axle is going to slip, but a single Snugnut makes it easier to line everything up.

  5. #5
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    if you happen to like a bike with super short chainstays, a 32/20 gear combo will set your chainstay length at just over 17". if you want it a bit shorter, you'd want to use 32/21 or 34/20. a 34t chainring will just clear the chainstay with a "normal" non-boost chainline, but it is not difficult to push it out a bit and line up your rear cog accordingly.

    that's my only beef with Surly—they should have just made the dropouts 3mm deeper to allow you to run a 32/20 with one less chain link and a super tucked rear end.

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    Quote Originally Posted by mack_turtle View Post
    if you happen to like a bike with super short chainstays, a 32/20 gear combo will set your chainstay length at just over 17". if you want it a bit shorter, you'd want to use 32/21 or 34/20. a 34t chainring will just clear the chainstay with a "normal" non-boost chainline, but it is not difficult to push it out a bit and line up your rear cog accordingly.

    that's my only beef with Surly—they should have just made the dropouts 3mm deeper to allow you to run a 32/20 with one less chain link and a super tucked rear end.

    break out that file

  7. #7
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    Quote Originally Posted by steevo View Post
    break out that file
    I thought about that, but it would not work. the dropouts have a ledge on the inside edge that won't allow the axle to move any further forward, even if the slot was deeper. you'd have to look carefully at the design to see how impossible that is.

    it would also void my warranty and I can't afford that chance. it's not a deal-breaker, just a critique.

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