cog to driveshell spline seems loose- Mtbr.com
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  1. #1
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    cog to driveshell spline seems loose

    For the past four years I have used Chris King and Kick A$$ cogs. They always seem to fit my Chris King Aluminum SS driveshells pretty snug. They also did very little "damage" to the spline. Sometime they took a little coaxing to get off. Early on I may have even had to file the Kick A$$ cogs to get them on, but no issues.

    This year I decided I was going to need more teeth out back, more than CK offers. I also wanted to steer clear of aluminum cogs.

    I ordered a few cogs from "XYZ" (name not important). One of the three cogs fits what I call snug. The other two seem to fit loose. They rock back and forth with the lockring not on. I would say they rock about 0.50 mm (big guess).

    Now for my question. Will the less than snug fitting cog, cause damage to the softer aluminum driveshell? If yes, enough to prevent other cogs from going on easily? Looking for advice from someone who has experienced this situation.

  2. #2
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    Quote Originally Posted by 29Again
    For the past four years I have used Chris King and Kick A$$ cogs. They always seem to fit my Chris King Aluminum SS driveshells pretty snug. They also did very little "damage" to the spline. Sometime they took a little coaxing to get off. Early on I may have even had to file the Kick A$$ cogs to get them on, but no issues.

    This year I decided I was going to need more teeth out back, more than CK offers. I also wanted to steer clear of aluminum cogs.

    I ordered a few cogs from "XYZ" (name not important). One of the three cogs fits what I call snug. The other two seem to fit loose. They rock back and forth with the lockring not on. I would say they rock about 0.50 mm (big guess).

    Now for my question. Will the less than snug fitting cog, cause damage to the softer aluminum driveshell? If yes, enough to prevent other cogs from going on easily? Looking for advice from someone who has experienced this situation.
    Why would you think the brand of the cogs is unimportant? The brand would tell everything we need to know about the cogs.
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  3. #3
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    I hope my request for information can be a success without mentioning the brand. I don't want to burn any bridges with the manufacturer, in case I need to ask for a refund. I am concerned "XYZ" might say that a little slop won't cause damage. Then I will have no response.

    I should have mentioned that the cog base is as wide as the King. So I am trying to make my question to the MTBR SS forum as general as possible. Perhaps someone, a few months later, might have a similar question with thier cog from company "ABC".

  4. #4
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    I would think that you want them to be snug. Movement in general can eventually allow them to bang (for lack of a better word) into one side of the spline while under load. If running a stainless cog which is harder than alu then yes, you could start to damage spline drive.

    I will say that I had a ti cassette on a set of Campy Record hubs for a while. While super light it ended up put several big bite marks into the spline drive which ended up needing to be replaced to the tune of $135! It needed to be replaced because when I went to swap out my cassette for a larger set for a really hilly race I was going to be doing, I could move/wiggle the cassette (individual cogs) back and forth and you could feel it when coasting and placing a slight load on the pedals off and on.

    It would not hurt to contact "XYZ" and ask them their opinion. Unfortunately, it has been a while since I have really played with any cassettes/cogs as I am running a freewheel set up on my White Industries.

  5. #5
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    I never thought a bit of looseness would be a problem because it shouldn't be moving back and forth. It's not a fixed gear so the only backwards force on the cog is a bit of chain tension when you are freewheeling and a little bit more when you backpedal. A properly tightened cassette lockring should provide enough clamping force through the spacers to stop it from constantly shifting. Banging shouldn't be a problem, and I've never felt any movement on my different freehub setups

  6. #6
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    Quote Originally Posted by 1SPD
    I would think that you want them to be snug. Movement in general can eventually allow them to bang (for lack of a better word) into one side of the spline while under load. If running a stainless cog which is harder than alu then yes, you could start to damage spline drive.

    I will say that I had a ti cassette on a set of Campy Record hubs for a while. While super light it ended up put several big bite marks into the spline drive which ended up needing to be replaced to the tune of $135! It needed to be replaced because when I went to swap out my cassette for a larger set for a really hilly race I was going to be doing, I could move/wiggle the cassette (individual cogs) back and forth and you could feel it when coasting and placing a slight load on the pedals off and on.

    It would not hurt to contact "XYZ" and ask them their opinion. Unfortunately, it has been a while since I have really played with any cassettes/cogs as I am running a freewheel set up on my White Industries.
    I agree. Aluminium splines are designed to used with a carrier style cassette; not those that are a stack of cogs. Most of the cog manufacturers with a wide base, will tell you if there are compatible with aluminium cassettes. However, there will always be some damage. I am still curious why you won't name the cog brand, unless the cogs were given gratis. Regardless, I have used King and Surly cogs on my aluminium carrier and they are both very snug. If cogs did not move after they were rendered tight, then using a thin BMX cog would not be an issue, which of course it is.
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  7. #7
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    Quote Originally Posted by aka brad
    If cogs did not move after they were rendered tight, then using a thin BMX cog would not be an issue, which of course it is.
    I disagree. My point about them not moving is just about them not moving backwards under the limited force from backpedaling. The force of the lockring is certainly not enough to prevent forward movement under pedaling force.

    The only point of contact against the drive shell would still be very small. The thinner cogs don't hammer their way through, they are simply pulled through. Look at the situations where people do run into problems with loose cog cassettes on Alu drive shells; they often have to use a lot of force just to pull the cassette back through the notches it made. In other words, there wasn't any movement going on there besides the slow creep through the aluminum

  8. #8
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    Quote Originally Posted by boomn
    I never thought a bit of looseness would be a problem because it shouldn't be moving back and forth. It's not a fixed gear so the only backwards force on the cog is a bit of chain tension when you are freewheeling and a little bit more when you backpedal. A properly tightened cassette lockring should provide enough clamping force through the spacers to stop it from constantly shifting. Banging shouldn't be a problem, and I've never felt any movement on my different freehub setups
    ^^^ this.

    While I don't have personal experience with a loose fitting cog on my CK hub(s), I'm convinced of two things:

    1) once the cog's spline shoulders rest up against the freehub's splines, there will be no damage unless the cog somehow "hammers" the freehub body's splines

    2) a thin cog can damage an aluminum freehub body simply by torque

    More opinion... I believe that as long as the cassette lockring is securely tightened, the "hammering" mentioned in #1 above can't happen so you'll be okay so long as you're utilizing a wide-base cog.

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  9. #9
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    Thanks for all the input.

    I sort of thought that once the cog is tight (40 N-m) and has shifted to one edge of the spline, that it will not shift back to the other spline edge. The working ringdrive should prevent that, so the theory goes.

    I am going to contact the cog maker and see what they say. I feel a little more confident having that discussion now.

  10. #10
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    rocking in a rotational direction will not hurt anything unless you're riding a fixed gear. I usually leave a little clearance so it isnt as much of a PITA to get the cog on and off. If you have it tight everywhere then it's likely to get stuck.

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