Cassette - Replace Ultegra 11-25 with Dura Ace 12-27
03-11-20, 11:50 AM
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Cassette - Replace Ultegra 11-25 with Dura Ace 12-27
I have Cervelo P2 that has an Ultegra 11-25 cassette. I'm thinking of moving that cassette to a direct drive trainer. Picked up a Dura-Ace 12-27 for cheap and wondering if that would fit on the bike so that I can leave the Ultegra on the trainer?
Any issues with the swap? Or is it a straight swap and no adjustments or issue?
Any issues with the swap? Or is it a straight swap and no adjustments or issue?
03-11-20, 12:21 PM
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Probably not. But it all depends on the specific model derailleur you have and the size of your chain wheels in the front if you want to be certain.
You might have to lengthen the chain.
You might have to lengthen the chain.
03-11-20, 01:18 PM
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03-11-20, 02:00 PM
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03-11-20, 02:01 PM
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Might be worth taking a picture of your rear derailleur with your setup in big ring, big cog. If your derailleur looks like it has some slack, it might be ok to give it the slightly bigger cassette, provided both are the same number of cogs. If the derailleur is already stretched all the way out, then I doubt it.
Anecdotally, I feel like I've heard that a 30T gear is the point where you would need a longer cage rear derailleur, but for the life of me I can't remember where I heard that from.
Anecdotally, I feel like I've heard that a 30T gear is the point where you would need a longer cage rear derailleur, but for the life of me I can't remember where I heard that from.
03-11-20, 05:20 PM
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03-12-20, 10:57 AM
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I’ve got a setup with a 28T on the cassette. I have a second chain for it. It works but that is the limit for my short cage Ultegra. There are derailleur adapters but I have not tried them. Wish I could build a cassette one cog at a time. Looked into it but the groupings offered did not work for me.
03-12-20, 05:40 PM
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FWIW, I use 10 spd 12-27 cassettes with my short-cage DA 7900 derailleur with no problem. So maybe you'll need a new longer chain, but otherwise you should be fine.
Have y9u thought about whether you really want to ride the 12-27? What chain rings do you have? On one bike, my chain rings are 53/39, so I very much appreciate having the 27 on hills and the lack of the 11 is no big deal. OTOH, I have another bike with compact 50/34 in front, and there are times on descents when not having the 11 is somewhat annoying.
Have y9u thought about whether you really want to ride the 12-27? What chain rings do you have? On one bike, my chain rings are 53/39, so I very much appreciate having the 27 on hills and the lack of the 11 is no big deal. OTOH, I have another bike with compact 50/34 in front, and there are times on descents when not having the 11 is somewhat annoying.
03-14-20, 08:32 AM
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Keep in mind the DA cassette will wear much quicker than a 105 or Ultegra. In my experience anyway.
03-14-20, 01:37 PM
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True. The outer cogs are Ti so they wear faster. That’s the price for being a weight weenie.
