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Old 09-06-11, 11:52 AM   #1
volosong 
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Is it possible to run a PG-1050 11-32T or 12-32T with a Shimano FC-6703 triple crank?

Looking at those low to mid twenties percent gradient ramps on a hill I want to climb on my Ultegra spec road bike. Bike currently has a FC-6703 triple crankset (52/39/30), a RD-6700 GS (long cage) rear derailleur, and 11-28T CS-6700 cluster.

Can I use a SRAM PG-1050 11-32T or 12-32T cluster with the triple crank and long cage derailleur?

Shimano specs say not, but with the long cage, maybe somebody here has been able to get it to work. I would think so because the short cage derailleur also says you can run an 11-28T; surely the long cage will allow more.
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Old 09-06-11, 01:53 PM   #2
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Long cage road derailleurs have the same large cog limitation as a short cage derailleur. The difference is how much chain can be wrapped on the derailleur to avoid a slack chain. The smaller sized chainring on a triple creates slack in the chain if the rear derailleur is not long cage. Mountain style RD's are designed to accept larger cogs, whether short, medium, or long cage.

Having said that, some people have been able to make a road derailleur work with a 32 tooth cog. This usually requires replacing the "B" screw with a longer one. The length of the derailleur hanger is also a factor on the maximum cog size that will work. Most Shimano rear derailleurs can be made to work with a 30 tooth cog.

I'm amazed at how often it's necessary to explain the difference between wrap capacity limit and cog size limit.
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Old 09-06-11, 03:00 PM   #3
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Originally Posted by volosong View Post
Looking at those low to mid twenties percent gradient ramps on a hill I want to climb on my Ultegra spec road bike.
Change the granny ring to something smaller (use a chain catcher and avoid the small cogs in the small ring if you exceed the rear derailleur wrap capacity) with 26x28 as low as 30x32 and 24x28 like 30x35.

It'll cost less and not introduce additional gaps in your gearing for flat ground.

Last edited by Drew Eckhardt; 09-06-11 at 06:26 PM.
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Old 09-06-11, 03:30 PM   #4
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Thanks, guys, for the info. Appreciate it.

I'll look around for a compatible, and smaller, granny gear. Sounds like a simple "fix". Just need to check my chain length. Not sure if I'll need a chain catcher if the stop screw is properly adjusted. Also, it's not a braze-on FD, so would have to see if a chain catcher can even be mounted.
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Old 09-06-11, 05:10 PM   #5
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Not sure if I'll need a chain catcher if the stop screw is properly adjusted.
FDs can have problems dumping the chain off if your granny ring is too small. Having said that, try it and see how it works before buying/installing a chain catcher.

I agree with the suggestion to replace the granny ring. You get more gear with (probably) less hassle.
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Old 09-06-11, 06:25 PM   #6
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Thanks, guys, for the info. Appreciate it.

I'll look around for a compatible, and smaller, granny gear. Sounds like a simple "fix". Just need to check my chain length. Not sure if I'll need a chain catcher if the stop screw is properly adjusted. Also, it's not a braze-on FD, so would have to see if a chain catcher can even be mounted.
The Third Eye, Deda Dog Fang, K-Edge clamp on, and N-Gear Jump Stop are all clamp-on. IIRC the Third Eye is the only one which is a universal fit with the others having different clamp sizes to match different seat tube diameters.

Last edited by Drew Eckhardt; 09-13-11 at 04:31 PM.
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Old 09-06-11, 07:34 PM   #7
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FDs can have problems dumping the chain off if your granny ring is too small. Having said that, try it and see how it works before buying/installing a chain catcher.

I agree with the suggestion to replace the granny ring. You get more gear with (probably) less hassle.
Ultegra crank with 24/42/52, SRAM 11-34 cassette, XTR rear derailleur:
http://home.comcast.net/~jeff_wills/...-grr%20008.htm
http://home.comcast.net/~jeff_wills/...-grr%20006.htm
They all work together fine, and I've never had a problem dropping the chain off the granny ring. Low gear is enough to climb an 18% grade with a full touring load.
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Old 09-06-11, 07:47 PM   #8
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Ultegra crank with 24/42/52, SRAM 11-34 cassette, XTR rear derailleur:
That's the secret of the 11x34 cassette working. As Al1943 noted some riders have reported success with a road rd clearing a 32T big cog but it's not sure thing and most report failure with a 34T.

I do agree with the change to the granny ring being the least expensive option and further agree with the chain watcher recommendation. I've done both on most of my bikes.
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