Where can I get one?

Discuss light weight issues concerning mountain bikes & parts.

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drew
Posts: 126
Joined: Wed Nov 05, 2003 8:52 pm

by drew

Looking for a 28T chainring for a 4 arm 104CBD chainset. 29 would do in a pinch. FSA and warhark dont have, any suggestions??

Tim the Pineapple
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Joined: Fri Oct 31, 2003 10:30 pm

by Tim the Pineapple

What crank you using ? Is it even possible to make 28T in 104 ?

by Weenie


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Superlite
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by Superlite

Doesn't it also have a 74mm or a 58mm on there to, I forgot the bcd on 4 arm cranks. 104mm is the outer chain ring, is that what you mean?

drew
Posts: 126
Joined: Wed Nov 05, 2003 8:52 pm

by drew

Superlite wrote:Doesn't it also have a 74mm or a 58mm on there to, I forgot the bcd on 4 arm cranks. 104mm is the outer chain ring, is that what you mean?


Yeah I want to replace the middle ring (104) with a 28/29 to run a 2 x 9.
If you can make a 32 in 104 surely 28 is possible? Cranks are Bontragers btw. Anyone help?????

drew
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by drew

Come on fellas, anyone???

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Frankie - B
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by Frankie - B

how about the rings of TA Specialites. Their French and make a huge number of different rings.
The rings are one of the lightest around and made of the very tough Zircal aluminum.
'Tape was made to wrap your GF's gifts, NOT hold a freakin tire on.'

nikh
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by nikh

Have you tried Anders aka The Machinist?

His website is on the links page.
PLAY DARTS! *WARNING* MUST HAVE A SENSE OF HUMOR TO PLAY!!!

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Frankie - B
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by Frankie - B

I will take a look in the TA list at my bike shop when i'm dropping by. Could take a week though!
'Tape was made to wrap your GF's gifts, NOT hold a freakin tire on.'

drew
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Joined: Wed Nov 05, 2003 8:52 pm

by drew

Frankie - B wrote:I will take a look in the TA list at my bike shop when i'm dropping by. Could take a week though!


Thanks, I appreciate that :)

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jer
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by jer

You might be able to get a 30 tooth, but not anything smaller. My guess is based on the fact the smallest ring that clears a 94 BCD is a 28 tooth and the smallest to fit a 110 is a 34. 104 is closer to 110 than 94 so even a 30 tooth might be out of the question.

Two things to keep in mind when considering a 2x9:

Your front shifting WILL suffer if you have more than a 12 tooth difference between your front chainrings. It can be made to work but I have yet to see it be shifting performance that I would race on (now.) Top pull, bottom swing derailleurs seem to struggle the most with the 2x9 combo too.

IF you throw the chain off of the inside ring with a 2x9 setup the chain can get stuck between the crank and the BB shell. Granny rings are designed and appropriately placed to prevent this. I DNFed a race I was doing well in because of this once. The chain got jammed so bad I had to pull the crank to get it out.

Even if you never use it I think a granny ring is 20 grams well spent.

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Frankie - B
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by Frankie - B

I'm riding the 2 x 9 setup for quite some years now in different setups. I never had any problems with a jammed chain or the bad functioning of the front mech. In my opinion it's a good working setup. Interesting, that you have a different opinion.
'Tape was made to wrap your GF's gifts, NOT hold a freakin tire on.'

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jer
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by jer

Well, i'm not the most graceful shifter in the world. (At least not when i'm racing.) What chainrings (brand and number of teeth) are you using, and what linkage is your front derailleur?


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Frankie - B
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by Frankie - B

Can't find it in the TA bible, but is has to be 32 or 30!

Good luck! :!:
'Tape was made to wrap your GF's gifts, NOT hold a freakin tire on.'

by Weenie


Dukester
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by Dukester

Extralite make a 30T ring specifically for 2x9 in 4-arm 104mm. I'm running one at the moment with a 44T and it works ok, although I have kinked a chain when I over-shifted during a race -you do have to be a little careful. I have found that the shifting depends a lot on the quality of the shift gates on the big ring. Mounting was also "interesting" as I had to slightly grind down the ends of the Spider arms because the chain wasn't sitting on the small ring squarely (=> ie you can't go smaller than 30T with 104mm!!!). A tricky move was making the chainring "nut" built in so you only have to use the bolt.
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30T_Octaramp.jpg

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