Maintaining Same Chain on Horizontal Dropouts- Mtbr.com
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  1. #1
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    Maintaining Same Chain on Horizontal Dropouts

    I have not gotten my SS bike yet so I can't do a physical test. I hope someone has done this before and can enlighten with your experience.

    I have two very different trails I would like to ride: a hilly trail and a fairly flat one. I would like to use a larger cog for the hills and a smaller one for the flat.

    Using a typical horizontal dropout (about 1.5 inches, I think) and one length of chain I don't want to change, and without the use of any spring tensioners, how many teeth difference can I expect to get if I place the rear wheel at the very fore position of the dropout with a large cog and the rear wheel at the very aft position with a smaller cog?

    I know different frames have different measurements so it will probably be different for different people, but a rough idea would help a lot.

  2. #2
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    I know a Dingle will work.
    I'm running 32/36 rings and 20/16 cogs on my Mary SS

  3. #3
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    I've used PowerLinks (two PowerLinks in the same chain) to easily shorten or lengthen my chain by a link or two in a jiffy.

    --Sparty
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  4. #4
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    To expound on what bigringrider said...
    If you keep the total number of teeth the same then not only can you use the same chain length but you can also keep the same axle position as well. It isn't always exact (the error gets larger as you use a larger difference in cog sizes), but it can make for much quicker changes between a fast gear and a trail gear. This is commonly used for dinglespeed setups, which is where you mount two chainrings up front and two cogs in the back so that you just have to loosen the wheel enough to switch the chain over to the other gear ratio.

    Like bigring, I did this for a while with 36x16 and 32x20 (both add up to 52 teeth) and it was very convenient.

  5. #5
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    Thought about the dinglespeed option for a while. However, there are some complications that is forcing me to think this way:

    I ordered a 29er. So to maintain the 32:18 ratio I have been using on my 26er, I need to move to 32:20 on the 29er for an approximate equivalent.

    Now for the second chainring, I want to use the granny 22T for my extended, 1 hour plus climbs. I've been using a 22:23 combo on my geared 26er, but the largest singlespeed cog available is 24T, so I'm need to train myself up a bit to use 22:24 on a 29er. No biggie here.

    Problem now is the teeth difference between 32:20 and 22:24 is 6 teeth. I was hoping that sliding the rear wheel back for the smaller cog will tension up the 6-teeth slack.

    I thought about getting a smaller middle chainring, like 29:18. There is only a 1-tooth difference, which the slack can easily be remedied by pulling back on the rear wheel. But 104bcd limit is 31T, and that is stretching it by having to grind down the spiders. Spiderless options for smaller tooth chainrings are limited to a single chainrings can't find 22T coupled with anything else.

    So powerlinks may be the way to go. 6 powerlinks on one chain is a stretch, so thinking I still need to pull back on the wheel to reduce the number of powerlinks needed. Anyone got a rough idea how many teeth that will eat up?

  6. #6
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    You would still only need two PowerLinks for that.

    You would size your chain like normal with one powerink for the ratio with the shorter chain
    Then from the left-over length of chain you size a small length that can be inserted in. Using a powerlink on each end of the insert you can quickly add it and remove it

  7. #7
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    Quote Originally Posted by boomn
    You would still only need two PowerLinks for that.

    You would size your chain like normal with one powerink for the ratio with the shorter chain
    Then from the left-over length of chain you size a small length that can be inserted in. Using a powerlink on each end of the insert you can quickly add it and remove it
    Perfect solution. So in the case of a 6-teeth difference, I would have a short length with 4 teeth and one powerlink on standby. So no need to fuss about rear wheel position and realigning the brakes every time.

    Perfect. Thanks for the insight. Never thought of the solution that way.

  8. #8
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    Thinking about it some more, with a normal 22-32-44 crankset and a normal cassette rear hub, you could theoretically ride your hill (22), trail (32), and road(44) if you spaced out the appropriate cogs on the freewheel with a single chain and 1 or 2 spare links in your pocket.

    So you could ride to your trail, stop and change the links for the climb, then at the end of the climb, stop and change the links again for the trail at the top of the climb, then change again for the road trip home.

    But then it won't be a singlespeed, would it? Just the efficiency of one.

  9. #9
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    1x2 SS Chainline Fitting

    If I were to get two 3/32" cogs at the back and have the chainline straight in between them, will the chainline be straight enough from the single chainring to switch between the two cogs?

    What type of chain do I need to be flexible enough to be able switch? 9-speed or 8-speed?

    The trail I ride has a section with an extended uphill that, at this time, I can't stand and mash the entire 1 hour plus length. I don't want carry a chain whip to change cogs mid-trail if I don't have to.

    In addition, if it does work with 2 cogs, will it work with 3 cogs?

  10. #10
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    You can only try the 3 cogs. It may work. I think if you keep the same chainlength and just drop teeth, it's about 3mm rearward axle shift per tooth downsize.
    I see hills.

    I want to climb them.

  11. #11
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    This dealy will calculate and show you various chainstay lengths for a given set of cogs/chainrings:
    http://eehouse.org/fixin/formfmu.php

  12. #12
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    You should ride it like a single speed and only use one gear.
    :wq

  13. #13
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    FWIW, with 1.5" of adjustment, if you started with enough chain tension as far forward in the dropout as you could get, you could safely then drop up to ten teeth by moving the axle back and keeping the chain the same.

    Don't know how you'd go, however, when it comes time to remove the rear wheel with the axle all the way forward.
    I see hills.

    I want to climb them.

  14. #14
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    Quote Originally Posted by Stevob
    Don't know how you'd go, however, when it comes time to remove the rear wheel with the axle all the way forward.
    Ah, right. You will need some room forward to slack the chain enough to slide it off the teeth. Guess that notion comes only with experience. Thanks.

  15. #15
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    Dude...if you want a 22 granny...just use derailleurs.

  16. #16
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    +1 for just ride it as a singlespeed.

    If you try and dingle speed with such a big tooth count difference, the chain length doesn't work out as well as you might expect; yes it's close but it will not be close enough. So not only will you be changing gears, but you will have to adjust chain tension as well.

  17. #17
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    Can anyone mash up a 35-45 degree slope for 1 hour straight? If so, let me know so I can aspire to reach that fitness level.

    The beginning part of the trail I can do 32:18 no problem. There are plenty of climbs that will give me a good enough challenge. It's that extended climb that's making me think dinglespeed.

  18. #18
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    Wouldn't a 45 degree slope be a 100% grade?
    :wq

  19. #19
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    yup
    I see hills.

    I want to climb them.

  20. #20
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    Quote Originally Posted by hchchch
    Can anyone mash up a 35-45 degree slope for 1 hour straight? If so, let me know so I can aspire to reach that fitness level.

    The beginning part of the trail I can do 32:18 no problem. There are plenty of climbs that will give me a good enough challenge. It's that extended climb that's making me think dinglespeed.
    one the xc races near me has ~4100ft of climbing up some fairly continuous steep climbs. I've never raced it SS but I have seen plenty of guys over take me on the climbs on SS bikes and only seen one take a break to walk. I don't know how these climbs directly compare to your climbs, and I'm not saying it to put down your abilities, but I think your body is capable of becoming much stronger than you think. It is perfectly acceptable to not want to go through all the hard training to get to that point, but it likely is possible

  21. #21
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    You would start of strong on SS, riding pass your buddies as your mash ahead like a hare. But the climb is long and arduous, and it is depressing once your legs quickly tire and you end up watching your buddies on gears slowly and steadily inch pass you like a turtle as you slowly push on the heavy cranks in your seat. It is then I contemplate shifting downwards, and usually do so not to get left too far behind.

    So in the mean time, while I work on my fitness and legs, I want to consider setting up the dinglespeed so I can at least enjoy the ride. But knowing it is physically possible is inspirational. Thanks.

  22. #22
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    Quote Originally Posted by hchchch
    You would start of strong on SS, riding pass your buddies as your mash ahead like a hare. But the climb is long and arduous, and it is depressing once your legs quickly tire and you end up watching your buddies on gears slowly and steadily inch pass you like a turtle as you slowly push on the heavy cranks in your seat. It is then I contemplate shifting downwards, and usually do so not to get left too far behind.

    So in the mean time, while I work on my fitness and legs, I want to consider setting up the dinglespeed so I can at least enjoy the ride. But knowing it is physically possible is inspirational. Thanks.
    Do like this.

    Run the single speed. IF your friends talk sh!t, respond with "Yeah, well, only one gear on this..." and then admonish them for riding with a full host of gears. You'll come up with a good way to do that. In the mean time, keep riding single and you'll get to where you need to be.
    :wq

  23. #23
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    "Discipline is the bridge between goals and accomplishments." --Jim Rohn

    Quote Originally Posted by hchchch
    You would start of strong on SS, riding pass your buddies as your mash ahead like a hare. But the climb is long and arduous, and it is depressing once your legs quickly tire and you end up watching your buddies on gears slowly and steadily inch pass you like a turtle as you slowly push on the heavy cranks in your seat. It is then I contemplate shifting downwards, and usually do so not to get left too far behind.

    So in the mean time, while I work on my fitness and legs, I want to consider setting up the dinglespeed so I can at least enjoy the ride. But knowing it is physically possible is inspirational. Thanks.
    disciplesofdirt.org

    We don't quit riding because we get old.
    We get old because we quit riding.

  24. #24
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    can you run 2 chainrings?
    then you can run 2 cogs on back, keep the tooth drop close on the front, and have 1 chain length with minimal movement.

    my crosscheck was set up as:

    dingle cog (fixed gear) rear 17/19 with a 38/40 front.
    i had a 22t ss on the flip side.

    my soma will be set up as a 32/34 front with the 17/19 fg dinglecog and in the spring a dos eno ss on the flip. if i need lower i'll set up as 30/32 up front. (currently running 18t ss with 32 up front)

    i also have a 17/21 dingle (fixed) - but the jump is just a bit too much from road / dirt.

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