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  1. #1
    The Next 100 Miler
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    Delete Front Derailleurs and Frame Design - Sram XX1

    I was reading this review of the Sram XX1 1x11 drive train and this quote caught my attention:

    "Front derailleurs can be finicky beasts. More to the point, they give frame designers a massive headache (particularly designers who are grappling with squeezing 29er wheels and wide tires into longer travel designs). Taking the front derailleur out of the equation allows for a much wider range of frame designs."

    So, are any bike companies changing frame designs specifically to use the XX1 drive train?

    I'm not an expert on frame design, so I don't know if the quote above is just marketing hype, or a real design benefit.

  2. #2
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    What amazes me is that:

    Bike companies can make an incredibly expensive new type of rear hub to squeeze 11 cogs on a wheel.

    Make all new incredibly expensive molds to create a new 'tweener tire (650B)

    Design incredibly expensive new cranks that only have one ring.

    CANNOT design a front derailleur that has the mechanism in front of the seat tube.

  3. #3
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    I think the problem is that most manufacturers use the same frame design from lower-mid range models all the way up to top-of-the line.

    So until such time that as there is a cheaper 11 speed system available that manufacturers can use in their lower end bikes, we probably wont see if there is any benefit or not.

  4. #4
    Si Vis Pacem, Para Bellum
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    It would actually be easier to build a frame without a dropout for a front derailleur. I could have a shorter chainstay and shorter seat stays and a seat tube. It would definitely make for a more playful bike.
    Big Wheels Keep On Rolling

    Forth Eorlingas!

  5. #5
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    Quote Originally Posted by MarkP View Post
    So, are any bike companies changing frame designs specifically to use the XX1 drive train?

    I'm not an expert on frame design, so I don't know if the quote above is just marketing hype, or a real design benefit.
    Not marketing hype, It's definitely a benefit. Some suspension are designed around a certain size front ring, when you're in the large or small ring it affects the suspension performance. So by using only 1 ring you are keeping the chain in the sweet spot for suspension performance.

    Are any manufacturers specifically designing frames around this? I don't think so, yet. I would think that if the 1x11 really takes off then you will see frames designed around a single ring. Probably long travel 29ers, as fitting a front derailleur and having short chainstays is tough to do on a long travel 29er. It could lead to even shorter stays on 27.5 and 26ers.

    The Kona Honzo is a 29er that was designed to have short stays and is not front derailleur compatible, so you could say they designed the bike around a 1x drivetrain.

  6. #6
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    Specialized 2014 epic world cup race bike is designed around a single front ring, so I guess they are already designing frames around 1x drivetrains.

  7. #7
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    From Dave Weagle's blog, this post, "single chainrings and the detrimental effects on bicycle suspensions used for climbing and all mountain type riding," challenges the idea that a bike has an "ideal" front chainring size for all riding situations:

    ...The amount of anti-squat that a suspension can develop is based on (among other things) the angle of the ground that the bike is riding on and the angle of the chainline. It just so happens that as a bike is climbing a hill, the amount of anti-squat drops because the direction of gravity in relation to the bike changes. What this means is that if you are pedalling along in your 32-18 on flat ground and have just the right amount of anti-squat, then start to climb a steep hill, say 15 degrees or so, the amount of anti-squat is going to lessen. It just so happens that moving the chainline downward, say like if you selected your 22T cog, increases anti-squat. In an Apollo 13 like turn of events, people actually use their 22T cog when they climb hills as steep as 15 degrees (you basically have to). The two changing anti-squat amounts balance out, leaving the rider with very similar riding characteristics while climbing in the granny and riding on the flat in the middle ring. Amazing, huh? As you may have guessed, the same goes for descending with a larger ring...

    ...Variable front chainlines are ALWAYS going to be a good thing for mountain bikers who ride their bikes on variable terrains. Without them, suspension bikes might still be considered a bad idea, and I would most likely be riding motocross.

  8. #8
    The White Jeff W
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    Re: Delete Front Derailleurs and Frame Design - Sram XX1

    The new Kona Process 111 is xx1 with no option for a front derailleur due to tire clearance.
    No moss...

  9. #9
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    Quote Originally Posted by MarkP View Post
    So, are any bike companies changing frame designs specifically to use the XX1 drive train?
    .
    2014 Norco Sight Carbon
    No front derailleur fitted as they are X01 or XX1 and no fitting like direct mount provided on the seat tube

  10. #10
    Trail Ninja
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    Quote Originally Posted by albeant View Post
    From Dave Weagle's blog, this post, "single chainrings and the detrimental effects on bicycle suspensions used for climbing and all mountain type riding," challenges the idea that a bike has an "ideal" front chainring size for all riding situations:

    ...The amount of anti-squat that a suspension can develop is based on (among other things) the angle of the ground that the bike is riding on and the angle of the chainline. It just so happens that as a bike is climbing a hill, the amount of anti-squat drops because the direction of gravity in relation to the bike changes. What this means is that if you are pedalling along in your 32-18 on flat ground and have just the right amount of anti-squat, then start to climb a steep hill, say 15 degrees or so, the amount of anti-squat is going to lessen. It just so happens that moving the chainline downward, say like if you selected your 22T cog, increases anti-squat. In an Apollo 13 like turn of events, people actually use their 22T cog when they climb hills as steep as 15 degrees (you basically have to). The two changing anti-squat amounts balance out, leaving the rider with very similar riding characteristics while climbing in the granny and riding on the flat in the middle ring. Amazing, huh? As you may have guessed, the same goes for descending with a larger ring...

    ...Variable front chainlines are ALWAYS going to be a good thing for mountain bikers who ride their bikes on variable terrains. Without them, suspension bikes might still be considered a bad idea, and I would most likely be riding motocross.
    Dave Weagle's statements don't seem to reflect recognition nor acceptance of modern day shock technology.

    Regarding the topic, here's another article touching on such a subject: Trail Tech: Single-chainring frame design - BikeRadar (mentions '14 Spec Epic World Cup Ed, Kona Process 111, and Norco Sight Carbon)

    The '14 Niner WFO9 and Kona Honzo are two more.

  11. #11
    The Next 100 Miler
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    Thanks all for the responses - I'm learning a lot!

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