DA 9070 RD + 30T?

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pdlpsher1
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by pdlpsher1

Ritxis wrote:short chain, you can add any link, would not have any problem in using this configuration


If you lengthen the chain, the chain would become too long in the 11x39 combo and rub against the RD cage. I've asked for pictures of a 11-32 and short cage setup in the extreme cross-chain combos and so far no one has posted them yet...

Ritxis
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by Ritxis

by adding one or two links, remove tension in the derailleur cage (red line) I do not think that there is no problem
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pdlpsher1
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by pdlpsher1

Ritxis wrote:by adding one or two links, remove tension in the derailleur cage (red line) I do not think that there is no problem


At 00:40 of this video you can see that there's little tension in the chain and the shift from 12 to 11 was very slow. At 1:26 you can see the chain becomes too short and the drivetrain is jammed. If you lengthen the chain the shift from 12 to 11 while on the small front chainring will not even happen!

https://www.youtube.com/watch?v=5e9jzsujzV0
Last edited by pdlpsher1 on Sun May 22, 2016 5:50 pm, edited 1 time in total.

Ritxis
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by Ritxis

I always amount a chain, i would add at least one link more what indicates the assembly manuals, no problem with derailleur (mechanic or electronic)

motorapido
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by motorapido

Use a Lindarets road link, and a medium cage and it will work fine, its exactly what is designed for

http://www.lindarets.com/roadlink/

muntos
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by muntos

So it will work for sure with a short cage Ultegra 6870 DI2 derailleur or it depends also on chainstay length, chainrings sizes, wheather... :)?

eric
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by eric

The 9070 short cage has a wrap capacity of 33t. Shimano is very conservative with wrap and max cog specs. A 50/34 and 11-30 is 2 teeth more in both wrap and max cog. But it will work unless your frame has an unusually short hanger (which reduces the max cog capacity). It's worked for many people. Going to a 32t cog is pushing it farther. You are more likely to have problems from too short a hanger, and the short cage can't take up all the chain. But that may not be a problem: on my bikes the small cogs are not useable in the small ring because the chain rubs against the inside of the big ring. This is common with 50/34 chainrings and short chainstay race bikes. So when I am using large cogs I make sure the chain is long enough to go over the big ring and largest cog, and don't worry if the chain is slack in the small ring and smallest two cogs, because I don't use them.

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pdlpsher1
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by pdlpsher1

muntos wrote:So it will work for sure with a short cage Ultegra 6870 DI2 derailleur or it depends also on chainstay length, chainrings sizes, wheather... :)?


I guess it depends on your definition of 'work'. Some consider the cross-chain combinations as irrelevant because they will never use those combinations. Just don't do what Nibali did when he tried to shift to a large chainring in the Giro mountain TT :-)


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Dokas
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by Dokas

Ritxis wrote:
pdlpsher1 wrote:I highly doubt you can run a 32 along with the large chainring up front, and a 11 with the small chainring up front. To get 11-32 gearing you'll need a mid sized cage to take up the chain slack. Here are two pics of the Ultegra Di2 mid-cage with the 11-32. There's a good reason why you need a different RD when using 11-32.

Image
Image
Image



short chain, you can add any link, would not have any problem in using this configuration


RD is no problem in the first picture?

Ritxis
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by Ritxis

Dokas wrote:
Ritxis wrote:
pdlpsher1 wrote:I highly doubt you can run a 32 along with the large chainring up front, and a 11 with the small chainring up front. To get 11-32 gearing you'll need a mid sized cage to take up the chain slack. Here are two pics of the Ultegra Di2 mid-cage with the 11-32. There's a good reason why you need a different RD when using 11-32.

Image
Image
Image



short chain, you can add any link, would not have any problem in using this configuration


RD is no problem in the first picture?



seeing the picture of the rear derailleur, with small chainring and small cog, It could lengthen the chain

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