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Old 09-24-11, 10:08 AM   #1
robgod
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Quiz time: What logo is this?

Hi all,
I've just bought a second hand bike that needs some work. I want to add a new chainring but I have no idea what brand it is. Theres no writing on it, just the logo. Anyone know what brand this is?



(And anyone know if I can get a new ring for it?)

Thanks
Rob
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Old 09-24-11, 12:19 PM   #2
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The brand is not important, you just need to know what the BCD (bolt circle diameter) of the crank is. It looks like a 4-bolt design, so just measure the distance between the center of two opposite bolts. Then buy a new chainring with the same BCD and it should work. I seriously doubt that you'd be able to find a ring from the same brand, even if you are able to discover what brand the crank is.
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Old 09-24-11, 01:02 PM   #3
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The brand is not important, you just need to know what the BCD (bolt circle diameter) of the crank is. It looks like a 4-bolt design, so just measure the distance between the center of two opposite bolts.
.
+1,
Brand doesn't usually matter, but there are exceptions, where sometimes you might occasionally need to file the inner edges of chainrings to match or at least miss the shoulders on crank arms. If it's an issue it's usually the outer, sometimes the middle and never the granny.

Criss's advice to measure the on center diagonal works with 4-bolt systems, but if yours has 5 bolts, it's a bit trickier since there's no way to directly measure the diameter. Instead you measure the on-center distance between two adjacent holes and multiply by 1.7 to get the diameter. No great precision is need since there are only certain options, usually 110 or 130 as shown on this list of all possibilities.

Also
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Old 09-24-11, 02:17 PM   #4
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For the bonus point, that's Icon.
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Old 09-24-11, 06:11 PM   #5
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Thanks for all your replies.

I'm now not sure if its the chainring that needs replacing or the chain (or both!). When comparing the chain to a new one, the old chain is visibly longer over just 5 or 6 links! (You can see from the photo where the chain is slack around the chainring) Do chains actually stretch?

Oh, and mechBgon - thanks for that. And apparently, Icon is a brand name for Trek. You get the bonus point

Last edited by robgod; 09-24-11 at 06:19 PM.
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Old 09-24-11, 06:42 PM   #6
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Thanks for all your replies.

I'm now not sure if its the chainring that needs replacing or the chain (or both!). When comparing the chain to a new one, the old chain is visibly longer over just 5 or 6 links! (You can see from the photo where the chain is slack around the chainring) Do chains actually stretch?

Oh, and mechBgon - thanks for that. And apparently, Icon is a brand name for Trek. You get the bonus point
Yes, chains stretch, but not the way your old elastic wasteband does. In chain "stretch" there's no distortion or elongation of the metal, but rather that the individual links can move apart as the pins and holes that connect them wear. That elongation increases the pitch causing what you're seeing. Looking at the photo, I suspect that both are worn to or past the point of replacement.

In your shoes, I'd replace the chain first, and then the chainring and possibly the cassette if necessary. Necessary meaning that the new chain skips under load.

For future reference, measure your chain and when 24 links which should measure 12" "stretches" out to 12-1/16. Rerplacing the chain before it's worn too far, saves the cassettes and chainrings.
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Old 09-24-11, 07:13 PM   #7
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Looks as if the large chainring is integrated into the crankarm. Am I seeing that right?
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Old 09-27-11, 06:30 AM   #8
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Looks as if the large chainring is integrated into the crankarm. Am I seeing that right?
Nah, its just dirty
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