Is this a stupid idea?- Mtbr.com
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  1. #1
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    Is this a stupid idea?

    Well, thinking about it now, it probably is. But I figured I'd ask anyway from an actuality standpoint as to whether or not it's even possible.

    Say you have 2 gears you really like. One for road riding, one for trail. Now, I've already found my sweet spot. It's 32-15. But what if you like 32-14 and 32-16? Can you put two cogs side by side on the rear hub and just manually (by hand) change the gear on your own? That way, if you're like me where you have a spring loaded tensioner, the tensioner should give/take accordingly for the few teeth difference in between the cogs.

    I really don't plan on even attempting this, since I like the way 32-15 feels, but I keep thinking... what if?

  2. #2
    What could go wrong ...
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    been done already ... its called a dingle
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  3. #3
    one chain loop
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    not gonna work, unless you have two chainrings.

    using a rear derailleur will work but not the common spring loaded tensioner.
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  4. #4
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    Quote Originally Posted by fishcreek
    not gonna work, unless you have two chainrings.

    using a rear derailleur will work but not the common spring loaded tensioner.
    Ahh... wait... because a spring loaded tensioner is only "set" for 1 straight path and would only be able to hit the gear in that path... so it wouldn't be able to stretch to the 2nd cog, even if I manually move it...eh? Is my thinking accurate?

  5. #5
    Retro Grouch
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    Quote Originally Posted by Roasted
    Ahh... wait... because a spring loaded tensioner is only "set" for 1 straight path and would only be able to hit the gear in that path... so it wouldn't be able to stretch to the 2nd cog, even if I manually move it...eh? Is my thinking accurate?
    No, it's not about the chainline. I will say this again and maybe you'll get it. It's all about chain wrap. The spring tension can barely hold the chain on the cog, that's why the tensioner says to use a chain as short as possible. If there is enough chain to skip, it will, with or without a tensioner. If the tensioner pushes down there will not be enough chain wrap. If the tensioner is pushing up, hard bumps will bounce the tensioner down; either way it will skip. There are tensioners designed to take up extra chain such as the <a ref"http://www.paulcomp.com/melvin.html">Paul Melvin</a>. Otherwise your stuck with one cog or need to use a derailleur. Now I'm not saying your idea will never work; it's just not designed to work that way and probably will skip.
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  6. #6
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    Ah, I see. I understand where you're coming from.

    Rookie question here - Do chain tensioners in single speed conversion kits typically have the same tension as your typical rear derailleur? I don't have my chain tensioner shipped in yet but I wasn't sure if it gave comparable results in terms of tension.

    I was aware of the fact that you have better luck if the chain is as short as possible while still being functional. I'll definitely do that when I get my chain and conversion kit in.

  7. #7
    I'm just messing with you
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    Quote Originally Posted by Roasted
    Ahh... wait... because a spring loaded tensioner is only "set" for 1 straight path and would only be able to hit the gear in that path... so it wouldn't be able to stretch to the 2nd cog, even if I manually move it...eh? Is my thinking accurate?
    You need to use two chainrings and two cogs. You'll have to move the tensioner pulley over when you "shift" too. It doesn't take long, maybe 30 seconds on my bike.

    You have to choose gears that let you use the same chain length too, for example a 2-tooth difference between the two chainrings and a 2-tooth difference between the two cogs.

    Quote Originally Posted by Roasted
    Do chain tensioners in single speed conversion kits typically have the same tension as your typical rear derailleur?
    I have a DMR tesnion seeker on my converted bike and it's a lot stiffer than a derailleur. It uses a linear spring, not a coil.

    Last edited by wv_bob; 06-24-2009 at 11:48 AM.
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  8. #8
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    Quote Originally Posted by Roasted
    Ah, I see. I understand where you're coming from.

    Rookie question here - Do chain tensioners in single speed conversion kits typically have the same tension as your typical rear derailleur? I don't have my chain tensioner shipped in yet but I wasn't sure if it gave comparable results in terms of tension.
    I would say the spring tension on a tensioner they are a bit weaker than that of the derailleur tensioner arm. The thing isyour comparing apples and oranges. Take a look at a derailleur on a bicycle. The chain wraps around the cassette cog and is held in place by the jockey pulley. The tensioner arm and pulley pulls the chain down and away from the cassette, but the jockey pulley acts as a pivot for the chain, so even though the tensioner arm is pulling the chain down, it does not decrease the chain wrap. Now push the tensioner arm forward; what will happen is the jockey pulley will actually rock forward, increasing the chain wrap. In other words, a derailleur performs two functions (well three actually); one function (or pulley) to control chain wrap and another function (pulley) to tension the chain. A spring tensioner has to perform both functions and does neither very well.
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  9. #9
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    If you want to set up a dinglespeed, you'd be better off with horizontal drops, eccentric BB or hub.

    You could the setup two rings up front and out back. That would give you two different gears and obviously, you'd figure out the gearing so the chain length would be the same in either gear.
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  10. #10
    singletrack bound
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    That's why they call them "singlespeed".......

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