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SRAM Red Shifting
#1
I have a Bianchi 928 frame that I put 2012 SRAM Red components on. I have installed the front and rear derailleur as described in the manual. Both derailleurs are working well and I can shift through all the gears and there is very little chain noise. The problem I am having is that when I am in the small chain ring and the smallest to cassette sprockets (gears 9 and 10) the chain slips or jumps on the front chain ring. It appears that possible the angle of the chain from the small front chain ring to the outside two cassette sprockets is too large. I have a Mavic R-Sys rear wheel and I have one small spacer (1 mm at most) between the wheel and the cassette.

Any ideas as to what may be the cause of the problem?

Jack
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#2
Hi Jack;

"Any ideas as to what may be the cause of the problem?" - strictly speaking, lack of operator knowledge.

Running the small front ring and smallest cogs at the back is strictly NOT RECOMMENDED, and is called cross-chaining. On a ten speed with double chain rings, avoid using the two smallest cogs with the small front ring, and the two largest cogs with the big front ring, and everything will work well.

The "20 speed" and similar advertising is not exactly true, in reality about 20% of the possible combinations do not work well.
Nigel
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#3
Hi Jack;

"Any ideas as to what may be the cause of the problem?" - strictly speaking, lack of operator knowledge.

Running the small front ring and smallest cogs at the back is strictly NOT RECOMMENDED, and is called cross-chaining. On a ten speed with double chain rings, avoid using the two smallest cogs with the small front ring, and the two largest cogs with the big front ring, and everything will work well.

The "20 speed" and similar advertising is not exactly true, in reality about 20% of the possible combinations do not work well.
Nigel
Reply
#4
Thanks Nigel,

I have heard of the cross-chaining that you describe. However, SRAM advertises their "Yaw" front derailleur saying that it allows you to use all the cogs in the rear cassette without the chain rubbing on the front derailleur. I assumed that this meant that you should be able to use all the cogs of the rear cassette. Perhaps SRAM is a bit optimistic in their advertising.

Jack
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#5
Thanks Nigel,

I have heard of the cross-chaining that you describe. However, SRAM advertises their "Yaw" front derailleur saying that it allows you to use all the cogs in the rear cassette without the chain rubbing on the front derailleur. I assumed that this meant that you should be able to use all the cogs of the rear cassette. Perhaps SRAM is a bit optimistic in their advertising.

Jack
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#6
sorry about the double post, seems to a be a symptom on IE.

Jack, your symptoms are more an indication of one or more of the following, than FD rubbing:
* marginal chain capacity on the RD.
* chain too long.
* tired spring in RD.
Nigel
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#7
The rear derailleur is barely a year old and it has about 1200 miles on it. I would hope the spring is still good. I will try shortening the chain first.

Thanks
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#8
The rear derailleur is barely a year old and it has about 1200 miles on it. I would hope the spring is still good. I will try shortening the chain first.

Thanks
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#9
(09-23-2013, 12:30 AM)jacke Wrote:  The rear derailleur is barely a year old and it has about 1200 miles on it. I would hope the spring is still good. I will try shortening the chain first.

Thanks

Make sure that you don't make it too short.
Nigel
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#10
I did not get if you had a double or triple up front and what crankset you are using, but it sounds to me like what is happening in those two gears is your chain is nipping the shift ramps/pins on the outer chainring. it has nothing to do with your chain length. It is quite common when mixing different brand components especially 10 speed bikes. Even spec'd from the manufacturer that way. What crankset are you using?
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
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#11
The crankset is a 53-39 SRAM Red.
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#12
The crankset is a 53-39 SRAM Red.
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#13
Jack I cannot find any documentation that supports the notion of cross-chaining being ok with the Sram Red and the yaw derailluer. what chain are you using? It is my experience for whatever the reasons that with some bikes the chain will nip the ramp points on the outer chainring during chain-crossing. It should not be done whether it hits the ramps or not. Thats the bottom line. But if you could, post us a link of where Sram says this
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
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#14
Here is what I read.

Instead of simply moving back and forth, the derailleur cage actually rotates to maintain a consistent angular relationship with the chain. We call it Yaw Technology, and it eliminates the need for shifter trim. As a result, shifts feel more direct, more precise, and combined with the new RED crankset and chainrings, delivers an unmatched performance advantage in front shifting

I interpreted the phrase "eliminates the need for shifter trim" to imply that I should be able to use all ten sprockets with either front chain ring. Now that I know that is not the case I feel better. I thought I had the system set up wrong. I shortened the chain one link and it doesn't nip at the chain points in 9th gear but still does in 10th gear. I am using the SRAM PC1090 chain for 10 speed derailleurs.

I generally don't ride in 10th or 11th gears but like I said I was concerned it did not have it set up correctly.

Thanks

Jack
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#15
I think you are good to go, sounds normal to me if all else is working properly. Just remember that the straighter you keep your chainline the less stress and wear and it will last longer and ride smoother. You have a nice Group.
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
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#16
(09-24-2013, 05:06 AM)jacke Wrote:  .....I interpreted the phrase "eliminates the need for shifter trim" to imply that I should be able to use all ten sprockets with either front chain ring. .......

Hi Jack;

Shifter trim is required on FDs as you move the chain across the range of rear cogs - nothing for cross chaining, which independent of the FD.
Nigel
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