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  1. #1
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    Thoughts on Boone Ti cog

    Here's the deal...I use a 15t King cog and in just a few months I have managed to bend some of the teeth slightly forward. This is because, underneath a few teeth, there is an area that has been machined out that is wider than the base of the tooth.

    Having not seen the Boone cogs in person, or even having seen a picture of a 16t Boone cog, I'm at somewhat of a loss. This is used on my trials bike and will certainly see a tremendous amount of pressure. Is the Boone cog up for it?

    Thanks

    Sean
    Sean Chaney :: Owner/Builder :: Vertigo Cycles LLC
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  2. #2
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by smudge
    Here's the deal...I use a 15t King cog and in just a few months I have managed to bend some of the teeth slightly forward. This is because, underneath a few teeth, there is an area that has been machined out that is wider than the base of the tooth.

    Having not seen the Boone cogs in person, or even having seen a picture of a 16t Boone cog, I'm at somewhat of a loss. This is used on my trials bike and will certainly see a tremendous amount of pressure. Is the Boone cog up for it?

    Thanks

    Sean
    Are you sure the teeth are bent? How about a pic?

    If you are bending steel King Cogs I would not use a Boone.

    What gear combo are you running? A 15t cog seems pretty small for trials.
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  3. #3
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    Also

    Quote Originally Posted by shiggy©®™
    Are you sure the teeth are bent? How about a pic?

    If you are bending steel King Cogs I would not use a Boone.

    What gear combo are you running? A 15t cog seems pretty small for trials.

    Also, if a section has been machined out that is most likely for weight savings, which you don't really need on a trials bike. I would look for a solid cog. Someone posted some pics a little bit ago of a Spicer Ti Cog and it didn't have any weight cut outs. It was heavy since it was a solid piece of Ti, but I'm sure it doesn't fail very easily.

    Brett at Boone I think makes the teeth a little shark finned on his cogs because it keeps the wear down on smaller cogs. Not sure if this would help you out or not. You could always email him.

    DT

  4. #4
    34N 118W
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    Boone photo
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  5. #5
    ali'i hua
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    Quote Originally Posted by Hollywood
    Boone photo

    2 more days!
    2 more days!
    2 more days!

    ok- how do i get drool out of my keyboard?

  6. #6
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    I know this has been said before but my search is playing up. How did you order your sprocket? I am only getting his jewelry on the boone site. Is there another site to order from? Please help. This is by far the sexiest piece of bike gear out there and I must have one.
    'When he's not in action, he's in traction.'

  7. #7
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    Quote Originally Posted by shiggy©®™
    Are you sure the teeth are bent? How about a pic?

    If you are bending steel King Cogs I would not use a Boone.

    What gear combo are you running? A 15t cog seems pretty small for trials.

    Trust me. It's slightly bent, and I mean slightly. It's not in immediate danger of complete destruction, but as I only have about 15-20 rides on it, and only one competition, I'm considering that its longevity isn't infinite.

    I could take a pic, but that would mean I have to pull the wheel back out and remove it, and quite honestly, I'm too lazy for that. (Since I'm running 4 bolt maggies, a 47mm wide rim and a 2.5 tire, taking the wheel out isn't the same as on your average MTB. You have to take off the chain, deflate the tire, squeeze it by the maggies while at the same time trying to get the King funbolts by the derailleur mount. Like I said, not interested in doing that right now. I'll take a pic next time it's off for service, or when my new frame gets here in a few weeks.

    Edit: OK, I caved:

    I'm running a 17/15. I designed an integrated spider and bashguard that mounts directly to my XTR 952 crank arm and uses a custom 17t stainless chainring. Ian at Forge-MTB made it for me last year. It looks like this:
    I'm not aware of another cog that would work in my situation, except for maybe the Boone. The Spicer is entirely too wide. I'm running a King SS rear hub with that one steel King cog and four modified plastic cogs (to save weight yet remain comp legal).

    thanks for the suggestions though.
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    Last edited by smudge; 03-04-2004 at 04:48 AM.
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  8. #8
    Fat Boy Deluxe
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    Quote Originally Posted by devlin
    I know this has been said before but my search is playing up. How did you order your sprocket? I am only getting his jewelry on the boone site. Is there another site to order from? Please help. This is by far the sexiest piece of bike gear out there and I must have one.

    It's all about the google search...

    http://boonerings.com/cr/orderformchainring.html

    DT

  9. #9
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by smudge
    Trust me. It's slightly bent, and I mean slightly. It's not in immediate danger of complete destruction, but as I only have about 15-20 rides on it, and only one competition, I'm considering that its longevity isn't infinite.

    I could take a pic, but that would mean I have to pull the wheel back out and remove it, and quite honestly, I'm too lazy for that. (Since I'm running 4 bolt maggies, a 47mm wide rim and a 2.5 tire, taking the wheel out isn't the same as on your average MTB. You have to take off the chain, deflate the tire, squeeze it by the maggies while at the same time trying to get the King funbolts by the derailleur mount. Like I said, not interested in doing that right now. I'll take a pic next time it's off for service, or when my new frame gets here in a few weeks.

    Edit: OK, I caved:



    I'm running a 17/15. I designed an integrated spider and bashguard that mounts directly to my XTR 952 crank arm and uses a custom 17t stainless chainring. Ian at Forge-MTB made it for me last year. It looks like this:


    I'm not aware of another cog that would work in my situation, except for maybe the Boone. The Spicer is entirely too wide. I'm running a King SS rear hub with that one steel King cog and four modified plastic cogs (to save weight yet remain comp legal).

    thanks for the suggestions though.
    You are putting a lot of force on very few teeth, front and rear. Unless you can get a Boone cog made without the cutouts (he might be able to) I think you are going to have to live with the fact you are going to go through cogs quickly.
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  10. #10
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    tough so far

    i am running a boone ti 19 toother. so far very tough. i am a clyde and hammer that poor little piece of ti and it still looks good. sexy piece of bling too.

  11. #11
    SS Chimp
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    send it back

    not that you wanna deal with it but i would send that sucker back to king. i got a 17 cog from them a while back that had a milling error and jen turned it around the same day and fedex'd it back...4 days total, door to door. they very well may tell you that you are outside the parameters of the design but it is worth a shot. call her and see what she says.

  12. #12
    theHeadlessThompsonGunner
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    Quote Originally Posted by shiggy©®™
    You are putting a lot of force on very few teeth, front and rear.
    Right. The problem is not the cog (King steel cog are stinking durable, in my experience). Rather, it's the total number of teeth you're choosing to wrap your chain around, and the resulting torque. There's just too few teeth to bear the load. I'm not up to the math in my head right now, but go with something like 22/20. Better yet, try 30/27 (probably not with a King, though--you'll be lucky if you can track down a 22t). I guarantee that, with 15 teeth on either end bearing the load from your chain, opposed to the 7 or so you're running now, you're not going to be bending King cogs.

    On the Surly site there should be something debunking 'Micro-Drive', a crappy concept from the middle 90s by Suntour (I think?) that reduced the number of teeth in favor of weight savings. The result? The same problem you suffer--inadequately distruted load. Be proud of your big manly legs (seriously--that's impressive), and get some big rings--front and rear.
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  13. #13
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    Quote Originally Posted by SDizzle
    Right. The problem is not the cog (King steel cog are stinking durable, in my experience). Rather, it's the total number of teeth you're choosing to wrap your chain around, and the resulting torque. There's just too few teeth to bear the load. I'm not up to the math in my head right now, but go with something like 22/20. Better yet, try 30/27 (probably not with a King, though--you'll be lucky if you can track down a 22t). I guarantee that, with 15 teeth on either end bearing the load from your chain, opposed to the 7 or so you're running now, you're not going to be bending King cogs.

    On the Surly site there should be something debunking 'Micro-Drive', a crappy concept from the middle 90s by Suntour (I think?) that reduced the number of teeth in favor of weight savings. The result? The same problem you suffer--inadequately distruted load. Be proud of your big manly legs (seriously--that's impressive), and get some big rings--front and rear.
    I appreciate the advice. However, I seriously feel that if the material wasn't machined away under the tooth, this wouldn't be a problem.

    I knew going into the design of my bashguard that the load per tooth would rise, but I assumed that it would have the biggest effect on the longevity of the chain, which I replace frequently anyway. As much as I wish I could claim that my "big manly legs" allowed this to happen, I think the reality is that there is less than 1mm of metal keeping the ends of that tooth (and two others) connected to the cog body. I think if that material weren't machined away, I wouldn't have this problem.

    As for replacing the rings, I wish it were that simple. It is a trials bike. And as I make an effort to ride to NBR (nothing but rubber) a larger chainring and therefor bashguard, is a hinderance. As it is, the geometry of my bike and that bashguard prevents my from physically landing on bash on a square edge...it's just not possible. The edge of an obstacle needs to approach the 80 degree range before my bash will touch...it's like extra insurance if you're in a UCI rules competition.

    Thanks everyone for the input. I'll send it back to King and see if they'll replace it with one that doesn't have the machined cut outs.

    Sean
    Sean Chaney :: Owner/Builder :: Vertigo Cycles LLC
    flickr :: www.vertigocycles.com

  14. #14
    theHeadlessThompsonGunner
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    Another thought...

    Buy a cheap BMX-chromo-stinking-heavy-cog (yes, the ones with the narrow bases), and JB Weld two smaller cogs to the sides. This will create a nice, wide base and a very strong cog that will probably hold up. I've a friend who did this for a 20t cog (before King got them going), and it's a sight--it sounds rather crude, but it's certainly sturdy. I can take a pic if you want.
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  15. #15
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    I wouldn't count on [I]anything[/I] not to bend in your situation!

    You're running 17x15? As in 17t front chainring?

    The smaller the chainring/cog combo you use for a given ratio, the slower the chain moves for a given input. In order to transmit the same amount of power at that slower speed, the chain must carry proportionally (if not the square of proportional) greater tension.

    Bottom line: I'm surprised you aren't snapping chains left and right - especially running trials with that combo - and I'm not surprised you're bending teeth. If you weren't using an aluminum-shelled hub, I'd suggest a 15t DX or Novatec cog - THICK steel, and much harder than what CK uses in their steel cogs - but even then I'm not sure I'd trust it not to bend. And even so, with the staggering stresses you're putting on your drivetrain, a stronger cog might just move the problem somewhere else.

  16. #16
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    Quote Originally Posted by smudge
    Here's the deal...I use a 15t King cog and in just a few months I have managed to bend some of the teeth slightly forward. This is because, underneath a few teeth, there is an area that has been machined out that is wider than the base of the tooth.

    Having not seen the Boone cogs in person, or even having seen a picture of a 16t Boone cog, I'm at somewhat of a loss. This is used on my trials bike and will certainly see a tremendous amount of pressure. Is the Boone cog up for it?

    Thanks

    Sean
    SS trials rider here, been runing a 22:18 for a while now (no comps or anything most just messing around). Its a king cog alu and there has been very little wear even though i had the chain too tight (i was using a phantom cog, but that set up has changed). As others above have said a larger cog front and rear will give better results and will last longer too.

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