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Short cage derailleur capacity

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Short cage derailleur capacity

Old 04-23-13, 07:52 PM
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Short cage derailleur capacity

I bought a takeoff wheelset off the 'bay, and it came with a brand new 105 cassette and 23mm Bontrager tires. It's useless to me (on the road) where I live because it's a 12-30, but I thought I'd throw it on a spare wheel for the trainer. I should have tried it right away but I took it off the hub before I thought of it. Anyway, does anyone know if a 30 tooth cog will function in a 6700 Ultegra derailleur? I know Shimano says it's not compatible but I was wondering if anyone had tried it. I also know I'll never need that cog for a trainer wheel; I'm more curious than anything.
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Old 04-23-13, 08:00 PM
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Likely not, but on the trainer just confine the derailleur to the smaller cogs and you will be okay. Have your chain set up for a smaller largest cog like you ride on the road.
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Old 04-23-13, 08:02 PM
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Ask the mechanics forum, but I dont believe it will. the derailleur cage will most likely get hung up on that cog, not enough pull or whatever you call it.

What do you need that 30t for anyways.
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Old 04-23-13, 09:44 PM
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check to see if you have the old 6700 or new 6700a rd. The pulley should have the capacity stamped on it if IIRC. The revised version can handle the 30t
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Old 04-24-13, 08:45 AM
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The only way to know for sure is to try it. The listed wrap capacity is fairly conservative. The length of the hanger also plays a part. There are people who made it works before.
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Old 04-24-13, 10:38 AM
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Should work if you have the proper chain length and B-screw adjustment. Experiment with the chain length at 1 or 2 links to find the sweet spot. My short cage Microshift works fine with a 32T rear/53T front or 32T rear/39T front.
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