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  1. #1
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    What chainring combination are possible with the Ultegra 6800 11-speed system?

    I am building a new CX bike for gravel grinding and occasional road/gravel touring. While I could go with a 10-speed triple setup (e.g. the Shimano Ultegra 6703 system), I am intrigued with the new Shimano Ultegra 6800 system. FYI, my frame for this bike will be a custom Ti frame with Salsa Vaya geometry. I will also use a tubular wheel setup (e.g. Hope hubs, Stan's Iron Cross rims, Stan's Ravens 700c x 35mm tires).

    For the bulk of my riding (unloaded gravel grinders), I am thinking of using a 36t/46t cyclocross chainrings paired with an 11-28t cassette. This should give me ample top and bottom ends for wind and hills of Kansas (e.g. the Flint Hills). This could also be paired with the long cage Ultegra RD 6800 rear derailleur that would give me the option of running an 11-32t cassette as well.

    But for touring (rails to trails rides; perhaps some mountain fire roads) I am exploring what options I have. For their 6800 Ultegra system Shimano makes chainrings as small as 34t and cassettes as wide as 11-32t. Does anyone know if I can pair the 34t chainring with the 46t outer ring (the standard Shimano setup for this smaller inner chainring is 50t/34t compact)? Another/additional option is to use a Shram's mountain 11-speed cassettes (e.g. 12-42t; Shram XG 1195). In either case, I might be forced to use a mountain rear derailleur (e.g. the Shram XO) to handle the rear derailleur capacity).

    If you have comments, please chime in.
    "I'm going to work so that it's a pure guts race at the end, and if it is, I am the only one who can win it." - Prefontaine

  2. #2
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    I just called Shimano. For the Ultegra 6800 crankset, there are four chainring options: 46-36T, 50-34T, 52-36T, and 53-39T. All combinations will fit on the same set of crankarms. While other combinations (e.g. 46-34T) might fit, they won't shift as well. However, with the wide range of available cassettes (11-23, 11-25, 11-28, 11-32, 12-25), the 6800 drivetrain provides a wide choice of gearing options by just changing chainrings and/or cassettes.
    "I'm going to work so that it's a pure guts race at the end, and if it is, I am the only one who can win it." - Prefontaine

  3. #3
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    Thanks for the update. It looks like you are going for a double in front - that would be my suggestion. I just switched from a triple to an Ultegra 6800 drive train on my road bike. My triple (105/ultegra combo with FSA crank) was problematic for 7 years. I had several techs say that they should never have made a triple with a 10-speed.

    I am going to look into a 44-34 for my cx bike. I can't remember who makes these chain rings, but they are made to work together. I too was told that changing a 36 to a 34 to make 43-36 won't shift as well. I have a 11-28 in the rear. For gravel grinders, the 50-34 is intriguing, but I mostly use my CX bike for CX and on mountain bike trails.

    For your wheels, I was looking at Hope hubs and Stans Iron Cross and ended up with Stans Ti hubs with Iron Cross rims. Dave from Speeddream wheels built them for me and said I wouldn't need the engagement of Hope hubs for CX and recommended I save weight instead. For CX, he was right. You can't get pretty colors, however. I'm not sure what tire pressure you want for gravel grinders, but you can't go above 40 lbs or so (I believe) with the Iron Cross rims. I over-inflated mine (to 50 lbs) to try to get them to seat well and heard a loud 'pop' 5 minutes later when the tire popped off the rim and exploded Stans all over the room. So if you want the option of running higher pressures, I think the Alpha 340's can take higher pressure.

  4. #4
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    Quote Originally Posted by miatagal96 View Post
    Thanks for the update. It looks like you are going for a double in front - that would be my suggestion. I just switched from a triple to an Ultegra 6800 drive train on my road bike. My triple (105/ultegra combo with FSA crank) was problematic for 7 years. I had several techs say that they should never have made a triple with a 10-speed.

    I am going to look into a 44-34 for my cx bike. I can't remember who makes these chain rings, but they are made to work together. I too was told that changing a 36 to a 34 to make 43-36 won't shift as well. I have a 11-28 in the rear. For gravel grinders, the 50-34 is intriguing, but I mostly use my CX bike for CX and on mountain bike trails.

    For your wheels, I was looking at Hope hubs and Stans Iron Cross and ended up with Stans Ti hubs with Iron Cross rims. Dave from Speeddream wheels built them for me and said I wouldn't need the engagement of Hope hubs for CX and recommended I save weight instead. For CX, he was right. You can't get pretty colors, however. I'm not sure what tire pressure you want for gravel grinders, but you can't go above 40 lbs or so (I believe) with the Iron Cross rims. I over-inflated mine (to 50 lbs) to try to get them to seat well and heard a loud 'pop' 5 minutes later when the tire popped off the rim and exploded Stans all over the room. So if you want the option of running higher pressures, I think the Alpha 340's can take higher pressure.
    Yes, I am going with the double up front (Ultegra 6800, 46-36T). Quite frankly, I think that the Ultegra 6800 offers an incredibly wide array of gearing, except perhaps for the loaded touring cyclist but that is not the purpose of my current build. The 50-34T crankset also makes a lot of sense, especially if they provide more cassettes with 12 as the smallest cog.

    I too will likely go with the Iron Cross rim, but I may spring for some colored Hope hubs. I have no problem going with very low pressure tires for grinding gravel. I have been riding Stan's Crows at 22-25 PSI for a couple of years now, and I love them.
    "I'm going to work so that it's a pure guts race at the end, and if it is, I am the only one who can win it." - Prefontaine

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