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  1. #1
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    does any make a 23 tooth cog?

    other than soma? if not I'm probably just gonna have to get a 22 tooth

  2. #2
    crotchety young dude el twe's Avatar
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    I doubt it. Why not get the Soma?

    And what the hell chainring do you have?
    Quote Originally Posted by CardiacKid View Post
    I explained that he could never pay me enough cash for the amount of work I had put into that bike and the only way to compensate me for it was to ride the hell out of it.
    IRO Angus Casati Gold Line

  3. #3
    Walks with a limp dijos's Avatar
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    what's wrong with the soma? plus, 52t ring?
    I am looking for a 52cm-ish lugged mixte or ladies frame. Pm if you got one.
    Quote Originally Posted by thebristolkid
    Last I checked, most college campuses were firmly attached to solid earth, which, in my experience, is typically adequate for riding a bicycle upon.

  4. #4
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    I've just been reading that the soma's aren't that good..I'm running 48/19 right now..just looking for something a little tougher.

  5. #5
    dumps like a truck
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    A 23 tooth cog will not be tougher. Unless I'm not grasping what you mean by "tougher".

  6. #6
    Senior Member pirate's Avatar
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    uh, if you want a tougher gear ratio, you need a smaller cog, not a bigger one.

    doh, this guy beat me to it

    maybe he's trying to develop a super-tough spin.
    “When the spirits are low, when the day appears dark,
    When work becomes monotonous, when hope hardly seems worth having,
    Just mount a bicycle and go out for a spin down the road,
    Without thought on anything but the ride you are taking.”
    -Arthur Conan Doyle


  7. #7
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    wouldn't lower gear inches make it easier to skid and what nots? I heard the guys from mash run 42/20 or something like that which gives them gear inches of 55.3..? right? I dunno?

  8. #8
    sharkfin. babychris's Avatar
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    Quote Originally Posted by alfiegee View Post
    wouldn't lower gear inches make it easier to skid and what nots? I heard the guys from mash run 42/20 or something like that which gives them gear inches of 55.3..? right? I dunno?
    lol.

  9. #9
    crotchety young dude el twe's Avatar
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    Those MASH dudes run pretty big gears. You ever watch the parts where they just spin through traffic downhill? That's 75+ inches.
    Quote Originally Posted by CardiacKid View Post
    I explained that he could never pay me enough cash for the amount of work I had put into that bike and the only way to compensate me for it was to ride the hell out of it.
    IRO Angus Casati Gold Line

  10. #10
    Track Tricyclist kidtwisty's Avatar
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    Quote Originally Posted by alfiegee View Post
    wouldn't lower gear inches make it easier to skid and what nots? I heard the guys from mash run 42/20 or something like that which gives them gear inches of 55.3..? right? I dunno?
    right. and you said you wanted your ride to be tougher.
    how would being able to skid more easily equate to this?

  11. #11
    Team Beer Cynikal's Avatar
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    I think he is referring to the quality of the cog folks.

  12. #12
    Senior Member mihlbach's Avatar
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    You have nothing to worry about with Soma cogs. I've used about every brand of fixed cog available, and Soma's are basically just as good as EAI, Surly, Dura ace, and Miche cogs.

  13. #13
    King of the Hipsters
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    I've used a number of different cogs, too, with the exception of Phil Wood's cogs, and, to me, EAI cogs seem the best, by far, and Soma...well...I didn't like my Soma cog.

    I have a thing about prime numbers, and in terms of cogs and chain rings, that means 13, 17, 19, 23, 43, 47, and 53 teeth.

    This winter, I've also discovered the charm of riding at a much lower gear inch than I had ever anticipated.

    I presently ride at 59 gear inches.

    For those not familiar with gear inches, the typical factory fixie, with a 16t cog and a 48t ring, has about 78 gear inches.

    I've ridden has high as 82 gear inches, and I need to ride at 72 gear inches or below in order to ride without a brake (I always ride with a front brake).

    Further, I have always intuited that the greater the number of teeth in total, the more mechanical efficiency one experiences.
    I couldn't prove this until just recently, when I picked up a book on mathematical proofs and the book addressed this very subject.

    At any given gear inch, the more teeth one has, the more mechanical efficiency, or smoothness, if one wants to think of it this way.
    At some point, though, the increased weight negates the increased smoothness/efficiency.

    Anyway, I have 53 tooth chainring that I like, and I ride it with a 19 tooth cog.

    How cool if I had a 23 tooth cog, for 60 gear inches and 23 skid patches (even though I don't skid).
    Last edited by Ken Cox; 01-23-08 at 06:08 PM.

  14. #14
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    can you explain the mathematics?
    Quote Originally Posted by andre nickatina View Post
    the guy must have been like holy ****? this kid on a fixie is killin it without engine motors.

  15. #15
    King of the Hipsters
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    Quote Originally Posted by conor
    can you explain the mathematics?
    Let me find the book.

    I have right here in plain view, somewhere.

  16. #16
    Ho-Jahm Hocam's Avatar
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    Seems like more contact area with more teeth, but each link is bending fewer degrees as it travels around the cog.
    Race-o-meter:
    Broken until next season

  17. #17
    Senior Member mihlbach's Avatar
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    Quote Originally Posted by Ken Cox View Post
    I've used a number of different cogs, too, with the exception of Phil Wood's cogs, and, to me, EAI cogs seem the best, by far, and Soma...well...I didn't like my Soma cog.

    I have a thing about prime numbers, and in terms of cogs and chain rings, that means 13, 17, 19, 23, 43, 47, and 53 teeth.

    This winter, I've also discovered the charm of riding at a much lower gear inch than I had ever anticipated.

    I presently ride at 59 gear inches.

    For those not familiar with gear inches, the typical factory fixie, with a 16t cog and a 48t ring, has about 78 gear inches.

    I've ridden has high as 82 gear inches, and I need to ride at 72 gear inches or below in order to ride without a brake (I always ride with a front brake).

    Further, I have always intuited that the greater the number of teeth in total, the more mechanical efficiency one experiences.
    I couldn't prove this until just recently, when I picked up a book on mathematical proofs and the book addressed this very subject.

    At any given gear inch, the more teeth one has, the more mechanical efficiency, or smoothness, if one wants to think of it this way.
    At some point, though, the increased weight negates the increased smoothness/efficiency.

    Anyway, I have 53 tooth chainring that I like, and I ride it with a 19 tooth cog.

    How cool if I had a 23 tooth cog, for 60 gear inches and 23 skid patches (even though I don't skid).
    Ken, your babble about prime numbers, gear inches, and tooth counts does not explain what was wrong with your Soma cog. A lot of people claim the EAI is better, but most people just repeat what they hear without actually perceiving any real differences. I can't honestly tell any difference between my Soma 17t cog and my EAI 17t cog*. Perhaps if I was on a smooth wooden track and had years and years of racing experience. But whatever minute differences that exist between these cogs don't matter on the road...all that really matters (aside from gear ratio obviously) is that the cog doesn't strip the hub, is reasonably quite, and doesn't wear too fast. They (EAI, Soma, Surly, etc.) all perform about the same on those terms.

    edit: *I'm talking about the basic EAI cog, not the gold super($$)cog, which I have never used.
    Last edited by mihlbach; 01-23-08 at 07:54 PM.

  18. #18
    cab horn
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    Quote Originally Posted by Ken Cox View Post
    I've used a number of different cogs, too, with the exception of Phil Wood's cogs, and, to me, EAI cogs seem the best, by far, and Soma...well...I didn't like my Soma cog.

    I have a thing about prime numbers, and in terms of cogs and chain rings, that means 13, 17, 19, 23, 43, 47, and 53 teeth.

    This winter, I've also discovered the charm of riding at a much lower gear inch than I had ever anticipated.

    I presently ride at 59 gear inches.

    For those not familiar with gear inches, the typical factory fixie, with a 16t cog and a 48t ring, has about 78 gear inches.

    I've ridden has high as 82 gear inches, and I need to ride at 72 gear inches or below in order to ride without a brake (I always ride with a front brake).

    Further, I have always intuited that the greater the number of teeth in total, the more mechanical efficiency one experiences.
    I couldn't prove this until just recently, when I picked up a book on mathematical proofs and the book addressed this very subject.

    At any given gear inch, the more teeth one has, the more mechanical efficiency, or smoothness, if one wants to think of it this way.
    At some point, though, the increased weight negates the increased smoothness/efficiency.

    Anyway, I have 53 tooth chainring that I like, and I ride it with a 19 tooth cog.

    How cool if I had a 23 tooth cog, for 60 gear inches and 23 skid patches (even though I don't skid).
    Mechanical efficiency with more teeth? Sorry, that doesn't make sense. If anything, the longer your chain the less efficient it is.

    The bigger your cogs/chainrings the longer they will last.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  19. #19
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    Quote Originally Posted by operator View Post

    The bigger your cogs/chainrings the longer they will last.
    sounds bout right...

  20. #20
    Senior Member mihlbach's Avatar
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    Quote Originally Posted by operator View Post
    Mechanical efficiency with more teeth? Sorry, that doesn't make sense. If anything, the longer your chain the less efficient it is.

    The bigger your cogs/chainrings the longer they will last.
    Even if more a few more teeth (but with the same ratio) is more efficient in some way (less friction?), the effect of adding a few teeth to your chainring and cog would be so minor that it would be basically irrelevant.
    Last edited by mihlbach; 01-23-08 at 07:53 PM.

  21. #21
    Sir Fallalot wroomwroomoops's Avatar
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    Quote Originally Posted by operator View Post
    Mechanical efficiency with more teeth? Sorry, that doesn't make sense. If anything, the longer your chain the less efficient it is.

    The bigger your cogs/chainrings the longer they will last.
    I read about this somewhere (Sheldon Brown-ish no-bull**** place), that smaller chainrings and sprockets will cause more stress on the chain and as a result, higher friction losses.

    Then there's that paper in "Human Power" that compared various gear systems - among them deraileur-equipped systems, and compared the transmission losses for various sprocket-chainring combinations. Even there, there was a trend to have higher efficiency (closer to 100%) with larger sprocket+chainring, although by no means a linear function.

  22. #22
    King of the Hipsters
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    Quote Originally Posted by mihlbach
    Ken, your babble about prime numbers, gear inches, and tooth counts does not explain what was wrong with your Soma cog.
    Babble, eh?

    How nice.

    That kind of talk just endears me to people.

    Maybe we could have dinner some time.

    In any event, I had some reluctance to name the Soma cog, because I might have gotten a bad one, and it seems wrong to take away from someone's livelihood over a chance event...and a lot of people read this forum.

    Anyway, I had an out of round cog from Soma.

    How could that happen?

    Certainly not because Soma doesn't try to market round cogs.

    I think an anomaly somehow slipped through the process.

    I would think a computer makes these things, and computers never make mistakes, right?

    In any event, just handling the various makes of cogs, the EAI cogs feel and look like higher quality.

    Subjective, I know, but very real to me.

    I regularly handle high-end machined parts, and the EAI cogs have that look and feel.

    =====

    Now I'll get a letter from Soma's attorneys telling me to either produce the allegedly out-of-round cog or retract my statement.

    Can I shortcut the process by retracting my statement before I make it?

    Post Script: I'll find the book that had explanation of the efficiency of greater numbers of teeth; actually, combined radii.
    Last edited by Ken Cox; 01-23-08 at 10:35 PM. Reason: After thought.

  23. #23
    King of the Hipsters
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    Well, I couldn't find the book, so I did an Internet search.

    I couldn't find one site that had the complete answer, but I'll just combine some of them.

    I still haven't found the proof I want.

    =====

    For any given gear ratio, say 2:1, many different gear diameters and numbers of teeth will work, as long as they have a ratio of 2:1.

    However, as the diameter of the gear pairs increase, the chain remains more straight as it reverses direction, and thus, each chain segment bends less.

    As each chain segment bends less, the entire drive train system experiences less "chain segment bending loss."

    One can further reduce chain segment bending loss, which involves not only the interaction between the pins and bushings, but the interaction between the pins and bushings and the faces of the gear teeth as well.

    The straighter the chain stays, or the larger the "corner" it turns, the less chain segment bending loss.

    Additionally, one can further reduce chain segment bending loss by replacing the bushings with bearings, so that the meeting surfaces between the gear teeth and the chain experience no friction.

    The so-called bushings of high-end 1/8" track chains correspond to bearings rather than bushings.

    At some point, the combined weight of the larger diameter gears and the more complex chain undoes the advantages of bearing surfaces between chain and gear teeth, and a straighter, less-bent chain.

    Where do the two curves cross?

    I don't know.

    However, somewhere between a small chain ring and cog combo and a large chain ring and cog combo; and somewhere between the simplest lightest 3/32" bushingless chain, and the heaviest, most complex chain with bushings/bearings, lies the optimum in terms of minimal friction, bending loss, and weight.
    Last edited by Ken Cox; 01-23-08 at 11:25 PM. Reason: typo

  24. #24
    Senior Member Johnny Nemo's Avatar
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    I don't think they make a 23 (for 23 non skidding patches), but maybe you could get a (non prime) 24?!

  25. #25
    King of the Hipsters
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    Check out this site:

    http://www.gizmology.net/sprockets.htm

    It explains chain design and how the engineers design the profile of the teeth for a given size sprocket.

    This site corrects a misconception I had about chain bushings:

    http://chain-guide.com/applications/...cle-chain.html

    Very good drawings.

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