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Old 11-20-09, 06:06 PM   #1
hankbrandenburg
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10-Speed Ultegra Chainring question

I have an Ultegra 5-bolt Triple Crank with a 10 speed cassette, and would like to replace the small 30T chainring with something in the neighborhood of a 26T ring.

Anybody have any experience with this that could recommend a vendor for the chainring?
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Old 11-20-09, 06:09 PM   #2
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You need one with a 92mm BCD. I'm not sure anyone makes one...

What's your cassette range?
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Old 11-20-09, 06:15 PM   #3
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Only one generation of Dura Ace used the 92mm BCD inner ring, which was only available in 30T. More likely the OP needs a 74mm BCD, such as: http://sheldonbrown.com/harris/chainrings/74.html#26
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Old 11-20-09, 07:15 PM   #4
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Do a little research before posting.

http://techdocs.shimano.com/media/te...9830676705.pdf
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Old 11-20-09, 08:08 PM   #5
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Didn't realize the 6703 Ultegra also used the odd-ball BCD. However, the 6603 model used 74mm and the 6600-series of Ultegra components were also 10-speed. OP: can you clear up which you have?

[Edit. Got rid of my options because davidad's is much better.]

Last edited by JiveTurkey; 11-21-09 at 12:43 AM.
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Old 11-20-09, 08:15 PM   #6
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26 lol
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Old 11-20-09, 08:51 PM   #7
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If you have the ****mano 6703 with the 92mm small ring you will have to get a TA adapter middle ring that will allow you to use 74mm BCD rings. May as well go with a 24t just in case you ever need it.
The 6603 uses a conventional 74 BCD ring.
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Old 11-21-09, 11:40 AM   #8
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I have the Ultegra 6603. Does that mean a 74mm BCD/26teeth specified for 9-Speed will work for me?
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Old 11-21-09, 11:59 AM   #9
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Quote:
Originally Posted by LUCAS View Post
I have the Ultegra 6603. Does that mean a 74mm BCD/26teeth specified for 9-Speed will work for me?
Some would disagree, but many would say it is okay to mix specified speeds of chainrings.
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Old 11-21-09, 12:34 PM   #10
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Quote:
Originally Posted by LUCAS View Post
I have the Ultegra 6603. Does that mean a 74mm BCD/26teeth specified for 9-Speed will work for me?
Yes, it will work. I've made the exact same change on numerous 7,8 and 9-speed Shimano triple cranks and even on a 10-speed Campy triple crank and they all work well. Generally, I've used generic 74 mm bcd rings as granny rings aren't pinned, ramped, etc the way the larger chainrings are.

I would recommend adding a "chain watcher" to assure the chain won't spill to the inside on an emergency shift under load. Shifts to the granny ring are often done in a real hurry after you realize the hill is a LOT steeper than you thought.
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Old 11-21-09, 01:57 PM   #11
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The 24t and larger will work.
The shift up to the middle ring won't be as smooth, but it is still easily done.
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Old 11-22-09, 02:17 PM   #12
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Quote:
Originally Posted by LUCAS View Post
I have the Ultegra 6603. Does that mean a 74mm BCD/26teeth specified for 9-Speed will work for me?
Yes.
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