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  1. #1
    Ole
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    Project Carbine SL 27.5

    Last season, I raced XC on a Carbine SL with a 120mm fork. This year, I want to try 27.5, but I want to stay with my Carbine SL. So I started the process of converting it.

    A few important features that make this possible:

    The Carbine SL and the Carbine are "identical" when it comes to shape. The Carbine SL has shorter travel, by using a 200x50 rear shock, the Carbine uses a 200x57. Same lenght shock on both, but on the Carbine SL, it is not allowed to compress all the way in. This allows a larger rear wheel on the Carbine SL with no risk that it hits the seat tube.

    I can play with the BB height by either using off center bushings for the shock (already using those now to shorten the shock by 3mm, which equals around 9mm at the wheel) or putting on a 200x57 shock, but using the air can from a 190x50 shock. The result is a 193x50 shock, which will lower the rear end around 20mm, which pretty much makes up the difference between a 26" and 27.5" wheel. A tiny bit lower, but I'll be lifting the front end about the same, so the BB height will be right where I want it. I'll get about 1 degree slacker head tube angle, which is fine.

    The Carbine SL fits a Rubber Queen 2.4 tire on a Flow rim. That tire measures 2.6", or 66mm, it is HUUUGE! It ends up bigger than many 27.5" tires.

    Knowing this, I put a Rocket Ron 2.25" on a Crest 27.5" wheel and inserted it into the frame. The tire is a pretty large volume for such a lightweight race tire. It ended up being a bit too big for the frame. So, no go.

    I also happen to know a guy who makes a living repairing damaged carbon fiber frames, and he also designs and makes some wicked saddles. He can repair pretty much any damage.

    Knowing this, I went bananas with a file and a Dremel. The result is below. Not pretty, but with plenty room for a good size 27.5" tire.





    The repair guy has already received the rear triangle, and he says he can make even more room, before fixing it. I'll post more pictures as the project progresses.

  2. #2
    Ole
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    Frame repaired!

    Ok, the repair guy is fast! I got some photos back from him today!









    I've written som more about the project here:

    Google Translate

  3. #3
    bike addict
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    Hope ur disability is paid up. A repair,no matter how good it looks results in the same strength of the original piece. Without doing FEA, it looks like that section is under torsional load.

    In summary, what you did was stupid. But someone had to claim the darwin award.

    Just because you can, doesnt mean you should.

  4. #4
    Ole
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    I'm not worried about the repair. The guy doing the repair has long experience doing carbon repairs, and he has never had a single repair fail. He offers 5 years warranty on his work. See some examples of his repairs here:

    Reparasjon av karbonrammer. - Jaeger-Liteseat

    Besides, I live in Norway, we all have full health coverage.

  5. #5
    Dude, got any schwag?
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    I'm thinking you should have had carbon guy relocate the drops for axle position. Good luck mein Freund.
    Billy

    Speed is sweet, it's like an avenue to
    ... Shredtopia!

  6. #6
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    Awesome! Love this kind of tinkering. I don't have the frame nor the kind of $$ right now to do this kind of experimenting but have always been a fan of engineering and the will to put in to action when wondering what would this or that do. Good luck and keep the updates coming.

  7. #7
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    Wouldn't the 275 dropouts for the Carbine have been a cleaner, cheaper, safer route to go?

    Hell, my hats off to anyone willing to take a Dremel to $2.5K carbon frame in the name of experimentation I guess.

    Hope it works out for you, I just converted my T2 to 275 last night and it feels amazing.

  8. #8
    Ole
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    Quote Originally Posted by trojans1993 View Post
    Wouldn't the 275 dropouts for the Carbine have been a cleaner, cheaper, safer route to go?
    Indeed, and that was always my Plan B. But this being a race bike, I wanted to explore ways to keep the weight down. The Carbine 275 rear end, with 142x12 and 160mm rear disc would add at least 300g. If the Dremel-hack doesn't turn out like I hoped, I'll bolt on a Carbine rear end and learn to live with the weight gain.

  9. #9
    Ole
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    Black matte SID 120 27.5 arrived today. Cut to 19cm it weighs 1504g witout the axle. My old SID 120 WC weighed 1327g at the same length. A bit of a pentalty there. But I must say, the matte black finish goes really well with the matte black carbon on the Carbine SL.

    It's about 2cm taller, and the 27.5" wheel will add another 1.5cm or so. So I basically get the geometry of a 26" Carbine SL outfittet with a 150mm fork, if I manage to lower the rear end just enough to compensate for the larger rear wheel. I think that will be perfect, I have even less need for quick geometry with the bigger wheels, they will roll over some of the things I had to steer around before.

    I can probably ditch the setbak seatpost for an inline one, and I might have to increase stem lenght by 10mm.

  10. #10
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    Project Carbine SL 27.5

    Sub'd

  11. #11
    Ole
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    It's a go!

    Ok, got the bike put together, and here's the spec:

    Rocket Ron 2.25 mounted to Light Bicycle Wide rims. 23mm inner width.
    193x50 rear shock. Frame set to 135mm travel. SID 120 27.5" up front.
    Head angle: 69
    Seat angle: 73
    BB height unsagged: 13.25"
    2mm tire clearance at BB
    2mm tire clearance at full compression

    I might shorten the rear shock another mm or two, and accept slight tire rub at full compression. Or even run 120mm travel rear, since that's really enough for the intended use of XC Racing. I'm not worried about slight tire rub, that used to happen on several bikes I owned in the past, with stock setup.

    Right now I've got the bike back to 26" and 200x50 rear shock due to winter riding with studded tires. Will post pictures when I get around to taking them.
    Last edited by Ole; 02-13-2013 at 06:50 AM.

  12. #12
    Ole
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    Finally some pictures:

    First in 26" for comparison:







  13. #13
    Dude, got any schwag?
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    Quote Originally Posted by Ole View Post
    Finally some pictures:

    First in 26" for comparison:






    Kick ass! What's it weigh? How 'bout a ride report?
    Billy

    Speed is sweet, it's like an avenue to
    ... Shredtopia!

  14. #14
    Ole
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    9.5kg (21 lbs) as pictured. With race wheels, lighter pedals and hopefully Kettle carbon/ceramic discs (if I can get them to work) it should be just a hair below 9kg (20 pounds).

    I can't test it properly until the snow has gone, which means another 2 months or so. :-(

  15. #15
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    Project Carbine SL 27.5

    Holy seat post

  16. #16
    Ole
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    Quote Originally Posted by kaymonster View Post
    Holy seat post
    Strangely enough, it's just the right length!

    The frame is a Large, and I'm 189cm, or 6' 2.5".

  17. #17
    Dude, got any schwag?
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    How's she ridin'?
    Billy

    Speed is sweet, it's like an avenue to
    ... Shredtopia!

  18. #18
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    How about an update?

  19. #19
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    Ole, very impressive! That thing must fly, a true rock, you got some balls. Can't wait for a ride report. Props!
    Once you go slack, you never go back!

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