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  1. #1
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    '11 Scalpel 3 Lefty vs. Fatty Ultra questions

    Hello, I am new to the forum.

    I recently purchased a used 2011 Cannondale Scalpel 3 bare frame. The bike was originally equipped with a Lefty that had 100mm of travel. I would like to know if there would be any problem with putting a Headshok Fatty Ultra with 80mm of travel on this frame? My concern is that it might throw off the geometry. 80mm of travel is good enough for me and weight savings is my motivation.

    Thanks in advance for any advise anyone can offer!

    '11 Scalpel 3 Lefty vs. Fatty Ultra questions-%24_58.jpg

    '11 Scalpel 3 Lefty vs. Fatty Ultra questions-%24_57.jpg

  2. #2
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    Do you own the Fatty? If so, measure the axle to crown. I think the 100mm Lefty has an a/c of 470. So, if the Fatty is close to that then the geometry should be close. Every 20mm shorter will steepen the head angle ~1 degree and 20mm longer will slacken it out ~1 degree.

  3. #3
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    No, I don't own it yet. I was about to bid on it on Ebay. I will ask the seller about the axle to crown length, thank you!

  4. #4
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    I've been in contact with the seller and he says the length is 478mm.

  5. #5
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    Then you should be within +/- 0.5 degree. You can have much or more variation with a skinny 2.0 tire vs a high volume2.4 tire. I'm not sure it's as stiff as a lefty, but,i would go for it. I had looked at a Fatty when i did many build and out was to pass up.

  6. #6
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    Yeah I decided to go for it. My next question now is about the drivetrain. If I do a 2x10 setup would I need a medium cage or long cage real derailleur?

  7. #7
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    Sram or Shimano derailleur? Which cassette, 11-34, 36? What chainings? Check this thread about cage capacities.

  8. #8
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    Well the frame I purchased already has a new SRAM XX front derailleur and a new SRAM ceramic BB30 bottom bracket so I will probably just go with SRAM stuff. I have my eye on an 11-36 cassette and a 42-28 crank. The link above was very helpful, thank you. Using that information I determined that I need a derailleur with a 39t capacity, however SRAM rates their long at 43t and their medium at 37t. So can I get away with using the medium or do I need to go with long?

    Is there any problem with running a Shimano rear derailleur with a Sram cassette? Any opinions on which is better?

  9. #9
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    My current '12 Flash Carbon came with a Shimano XT RD and a SRAM cassette that was on a SRAM hub with the stock wheels, but now on a Reynolds hub. So to answer your question that setup works fine.
    '12 Flash 29r C3 with a few mods
    '10 Synapse 5 Carbon with a few mods as well..

  10. #10
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    Ok, now I'm looking at some Formula R1 brakes. The ones I'm looking at have a 180mm front rotor and a 160mm rear. Will this work with the 26" Scalpel with the Fatty Ultra headshok on the front? The cables included are 750mm for the front and 1500mm for the rear.

  11. #11
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    Quote Originally Posted by ozarkmtnbiker View Post
    I have my eye on an 11-36 cassette and a 42-28 crank. Using that information I determined that I need a derailleur with a 39t capacity, however SRAM rates their long at 43t and their medium at 37t. So can I get away with using the medium or do I need to go with long?
    I believe that the SRAM medium is a 37t max. So, if anyone has run a medium cage with that setup, i hope they will comment. I personally would end up with a long cage just to be safe.

    I have heard of Pro's and experienced riders using shorter cages and would just make sure to not cross chain where the maximums would be exceeded. I would hate to see what happens if a derailleur is pushed past its limit.

    Quote Originally Posted by ozarkmtnbiker View Post
    Is there any problem with running a Shimano rear derailleur with a Sram cassette? Any opinions on which is better?
    No problem mixing and matching unless you do rear shifter/derailleur mixing. I believe Shimano is a 2to1 ratio and Sram is a 1to1. So, keep the rear shifter and derailleur the same brand. Cassette won't matter.

    Quote Originally Posted by ozarkmtnbiker View Post
    Ok, now I'm looking at some Formula R1 brakes. The ones I'm looking at have a 180mm front rotor and a 160mm rear. Will this work with the 26" Scalpel with the Fatty Ultra headshok on the front? The cables included are 750mm for the front and 1500mm for the rear.
    Hoses may need to be shorted. But, that is true with almost any brake you will buy. I've got RX and they work pretty well. R1's are supposed to be even better. Enjoy.

  12. #12
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    Some of the Formula R1 brakes that I'm looking at include an adapter for mounting to an IS frame and some do not. Do I need this adapter (keeping in mind I'm using the Fatty Ultra fork)?

    No problem mixing and matching unless you do rear shifter/derailleur mixing. I believe Shimano is a 2to1 ratio and Sram is a 1to1. So, keep the rear shifter and derailleur the same brand. Cassette won't matter.
    But using a Shimano shifter with SRAM front derailleur is ok? Just not the rear?

  13. #13
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    The picture of the fork you posted has an IS mount. You will need an IS adapter for a 180front/160rear if you're going with a 180 rotor up front. If you use a 160 on the rear and thats the frame you're getting, no adapter is needed since it has a post mount.

    I've heard its only an issue for the rear. i have used an old '97 Shimano front shifter with an '09 SRAM x7 front derailleur with no perceivable issue. YMMV.

  14. #14
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    Thank you!

  15. #15
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    My pleasure. i just built up an '08 Scalpel myself. I went with a Manitou Marvel and am running 1x9. I'm still trying to dial in the rear shock since the chainstay makes it different pressure than normal. Enjoy the new toy. The build up always relaxes me.

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