How do I go from this to this?- Mtbr.com
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  1. #1
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    How do I go from this to this?

    I want to convert my old 90's 26 rigid 1x8 to a SS. What are the options? Ideally I don't want to run a tensioner. I'm mainly wondering what I need to do for a SS cassette? I would like to reuse my crank, maybe middle ring and bash guard.


    my 1x8
    How do I go from this to this?-my-marin-img_3381.jpg

    SS I found on web
    How do I go from this to this?-marin-ss-capture.jpg
    Ridley CX, Stumpjumper Carbon HT, Surly Wednesday

  2. #2
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    without a tensioner you are limited to an eccentric rear hub or magic gear

    as for "cassette" you only need a ss cog and the will depend on what gear ratio you want and if you are running magic gear that will determin cog size

  3. #3
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  4. #4
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    There's a few ways to go about it. The best long term solution with no tensioner is a WI ENO eccentric hub (IMO). You'll need to get your chainline right which would probably mean using the outer chainring position on a 3x crank. May need to move some BB spacers around too?

    Another option is a EBB for threaded BB's. Trickstuff pretty cool contraption, I've been tempted to try one.

    Magic gear is an option, but not a great one IMO. Once the chain stretches you'll need to change gear ratio's or put a new chain on, but it leaves you lots of room for chainline adjustability. You'll need a spacer kit for this one, and a Surly cog.

    Do some reading on the link Mack Turtle provided, figure out what chain tensioning technique you'd like to use, then go for it. A tensioner is the quickest, easiest, and cheapest way to build a reliable system, but I completely understand your desire not to run one.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

    Stop asking how much it weighs and just go ride it.

  5. #5
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    I think magic gear is the first thing to try. It requires less cash investment. Then if you change your mind about going SS, that's cool. Then if you love SS and that bike more, get an eccenntric ENO hub rear wheel for it.

    If I were you I would try to use the existing chain and middle chainring on the bike already. Then you need to buy a single speed cassette spacer kit. Remove the cassette and take it apart. If it is an old HG style cassette the various cogs come off independently. Find a gear calculator app or web resource. Find a combination with your middle ring that is realistic from the rings you have from your cassette. Then convert your rear wheel using this cog and the spacer kit to obtain a straight chain line.

    Determining the chain length is tricky. Only if you're lucky will you find the magic gear using the approach I have described above.

    After some dirty fiddling you will have a single speed. The chain can be a little too slack yet still work. Too tight is not okay.

    Alright, you have found the ballpark. This set up is only temporary and a model for what you are going to do with a new chain and a proper SS cog.

    You can ride with the HG sprocket and old chain to see if you like the gear ratio and the tension is okay. But you cannot rely on this to be safe.

    Your old chain is probably stretched, so your estimated set up is not accurate. You'll have to take this into account too. A new chain will be shorter. Look up how to measure chain stretch with a ruler on the web.

    I'll end with this...a tensioner is easier to set up an SS with, but I don't like tensioners.

    Sent from my LG-H910 using Tapatalk

  6. #6
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    I used a medium worn chain (>.5 but less than .75 according to park tool). And I used my middle ring 34 and my 16 tooth gear on the cassette, and found the length was right at a full link. I put the chain together and the tension was pretty good. With that bike, and that age of a chain, I probably have enough of a magic gear to get started.

    I am putting some avid SD 7 levers on her since it had integrated brake / shift pods and new brake cables, then I will give it a shot.
    Ridley CX, Stumpjumper Carbon HT, Surly Wednesday

  7. #7
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    Sounds promising. How about some more pics please?

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  8. #8
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    Quote Originally Posted by Jack Burns View Post
    Sounds promising. How about some more pics please?

    Sent from my LG-H910 using Tapatalk
    Not the most exciting pic yet. Should have more parts on the bike by Sunday. Might even be ride-able.

    How do I go from this to this?-marin-ss1.jpg
    Ridley CX, Stumpjumper Carbon HT, Surly Wednesday

  9. #9
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    34 x 16 to me is close to too hard of a gear for the hills where I live.

    Just saying. What sort of grades are you expecting to ride up?

    16t is commonly used. Mated with a 34 t chainring is a hard gear. If your going to ride hilly trails I suggest a bigger cog put back.

    You should be aware that cogs from a cassette are designed to shift the chain off. Not a good thing for cranking hard up a hill. I want to be clear that I suggested using the original cassette cogs to mock-up a basis for finding a magic gear possibility. Also, if the chainring has ramps, gates, and pins, you shouldn't use that for the same reason. You would need to figure out your BCD and get a plain chainring.

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  10. #10
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    Our trails don't have any long sustained climbs. I based my choice on first on what combos I had in old parts, second trying to be close to 2:1. I accept it might be a little hard, but a good place to start with minimum investment. If it goes OK from a ratio, I will buy a chainring and cog and cog spacers. If it doesn't work from a ratio, I will research other Magic gearing with the same chain length but easier as my 34 16 and if there some, I will try and mock it up.
    Ridley CX, Stumpjumper Carbon HT, Surly Wednesday

  11. #11
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    Good job!

    Top of the morning to ya!

    Trickstuff
    Instagram: kimthecyclist

    -16 Moulton TSR2 (Automatix)
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  12. #12
    Downcountry AF
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    Quote Originally Posted by KK89 View Post
    Top of the morning to ya!

    Trickstuff
    Apparently you missed post #4 where I mentioned the Trick Stuff BB. There also the Philcentric BB. Phil Wood & Co.
    Rigid SS 29er
    SS 29+
    Fat Lefty
    SS cyclocross
    Full Sus 29er (Yuck)

    Stop asking how much it weighs and just go ride it.

  13. #13
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    A half-link chain is a good option to try with a magic gear setup.

  14. #14
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    half-link chains suck. a chain with a single half-link on it, however, is a good option.

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