Would this work?- Mtbr.com
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  1. #1
    DSR
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    Would this work?

    So I'm in the process of building up a do-everything steel 29er - basically a Karate Monkey but with an EBB. I'm gonna have the rear disc wheel built up with an XT disc hub so that I can use spacers and run it as an SS (primary use) but then easily and cheaply change it to a 1x9 if I'm so inclined. Now to my question...

    With an unramped chainring and the EBB, could I put two cogs on the freehub (with minimal separation to keep the chainline tight) and create a pseudo flip-flop? This would basically be like the new White dual-cog freewheel that's coming out. I assume this would work. If so, second question then would be how much size difference I could run between the two cogs and still be able to make my adjustment with just the EBB (versus adding/reducing links)? Switching to the 29er, I'm probably gonna run 32x19 or 32x20 as my main ratio but would like to also have a 32x16 or so for commuting or flats. I just don't know how much "travel" there is in the EBB. Any insight? Maybe the best solution is to just have two chains and throw the commuter chain when using the smaller cog.

    Oh, and I understand that some might say that it's no longer a singlespeed. My definition of singlespeed is no shifters, but I don't really care either way. The idea here is versatility and utility.

    Thanks in advance! S

  2. #2
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    The Spot spacer kit should allow that to happen. You can use at least a two tooth differential in the rear (like 16t -18t) . Maybe up to 4. IMHO you are still singlespeeding afterall you can't change
    your gearing on the fly with that set up can you.
    The chainring should line up with the spacer between the cogs. Use BMX cogs (unramped) for the
    chainline will always be off a bit and a ramped cog will throw the chain when torquing the drivetrain.

  3. #3
    all hail der Fuhrer Bush
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    I doubt it but what do I know

    since I've never played with an eccentric on a SS I don't know for certain, but I know the eccentric on my tandem wouldn't suck up a 3-tooth difference.
    don't be a loser and buy somebody's ready-made "kit" when all you need is some probably free for the asking cog spacers from your friends at the LBS and a couple of old twisttooth uniglide cogs.
    too bad you have an eccentric, if you had horizontals you could do what I just suggested to the guy who posted "quick and easy formula for chain length" here. That's a cool way to have two different gears, without a derailleur as a tensioner. would be a pain in the rear to have to loosen and tighten the eccentric every time you wanted to "shift" and without loosening it, not sure if your wheel would come out so you could manually "shift." If it would, well there ya go, in my book a better way because you would have two perfect chainlines instead of two slightly off chainlines. SS bikes without tensioners tend to run roughly if the chainline ain't exact.

  4. #4
    DSR
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    Yeah, the EBB probably wouldn't take up much slack. I may go with the two chain idea. SRAM chains are so easy to take on and off. And the EBB is easy to loosen and re-tighten. Easier than horizontals, especially with discs involved. Anyway, I'll give it a whirl. Should be fun. Thanks, S

  5. #5
    mtbr member
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    From someone who actually has an EBB...

    And has done it.

    It depends on the exact combinations of cogs, chainrings and chainstay length.. I have run a 4-tooth spread with my EBB before, but getting the exact combination that you desire may not be possible.

    for example on my frame I had an 18t and a 20t on the freehub body and could "shift" between then with the EBB, I could have done a 21 or 22 but there was no way to make it fit say 16 thru 20 without altering the chain length, I'd have to take a link out to fit the 16 but then the spread would drop to like 14-18. Maybe a half-link would have done it but I wasn't really that interested in hitting a specific range.

    I put both cogs on so that the perfect chainline dropped between them so there was as little deflection as possible in both gears. If you use 8 or 9 speed spacers from a cassette with 1/8" chain you have to put two spacers between the cogs or the chain will hang up on the bigger cog sometimes. If you use a deraileur chain then it shouldn't matter.

  6. #6
    Nouveau Retrogrouch SuperModerator
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    Or you could run two rings in front and 2 cogs on the rear. Play with the combo to get the minimum chain length change. That is what the White Ind. 2-cog FW/2-ring chainring is for.
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  7. #7
    DSR
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    Wow, two front rings... hadn't thought of that! As usual, thanks for all the thoughts folks. I'll just have to experiment a bit. And yeah, I'll probably have to run an 8 or 9-speed chain in order to keep the chainline as straight as possible. I can get SRAM chains pretty cheap fortunately. I'm thinking that the two chain option is best since I won't need to change anything on the trail, just in the garage when switching between mountain and road gearing basically. And the SRAM Powerlinks are pretty easy to pop on and off (and re-use). Anyway, thanks again for the insight. Maybe I'll get lucky on the spread I can get out of the EBB alone. We'll see. S

  8. #8
    Nouveau Retrogrouch SuperModerator
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    With the 2x2 the chainline stays the same. Large ring/small cog on the outside for the road and small ring/large cog on the inside for the trail. Easy to change on the ride. Just loosen the EBB or remove the wheel and move the chain from the outside to inside.
    mtbtires.com
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