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  1. #1
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    Pros and Cons of Al vs Carbon SB-66

    I realize that no one has ridden both yet, but what would you guys consider the pros vs cons of choosing between an Aluminum or Carbon SB-66.

    If cost was not a concern and you could have your pick of either, which would you guys pick and why?

    I have not had a full carbon bike before and I'm struggling with the choice between the two. Maybe those who have ridden both an ASR 5 Alloy and Carbon have some input.

  2. #2
    T.W.O.
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    Aside from carbon would be a bit lighter, less shock, stronger, looks better, and stiffer. Carbon frame can be reinforced at particular parts that need strength or durability and easier to fix than alu.

    I expect to get scratches riding mtb, the first time I got the scratch on my Mojo my heart skip a beat After that it's business as usual

  3. #3
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    If cost was not a concern and you could have your pick of either, which would you guys pick and why?
    Full Al for me. I was plenty bummed when my choice of the '08 575 was full cf rear or partial, no full Al option. In my defense it has to do with the terrain I ride in Phoenix. Every drop of the bike is a potential granite strike. If I rode Alpine trails, or trails with nothing more than pine duff and tree roots to worry about I'd have no problem with CF. As it stands in my neck of woods, CF is simply not the right tool for the job. Just last week I put 12 coats of clear finger nail polish on a small chunk of missing CF material. This happened when I failed a rock step-up at less than walking speed. I'll take the paint chips and scratches any day. But that's just b/c of where I ride.

  4. #4
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    With limestone ledges and roots everywhere you look down here I only ride Al bikes.

  5. #5
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    Full aluminium for me. I had a Lapierre Spicy 916 with a carbon rear and it snapped in transit, still don't know how or why but it was at the point of the wheel dropout, and whatever did it tore off the mech + hanger, snapping the frame (and not the hanger!). Obviously one frame isn't enough to say all carbon = bad and there's plenty of happy riders out there on carbon bikes. But for me, I don't like having that in the back of my mind, I don't want to end up treating a mountain bike like a delicate antique!

  6. #6
    Ka-coo-ka-cha!
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    Quote Originally Posted by eatdrinkride View Post
    ...Just last week I put 12 coats of clear finger nail polish on a small chunk of missing CF material...
    Um, this will not save you from a failure. As a friendly word of advice have a shop check it out.

    My credentials? Mechanical engineer (MS Solid Mechanics) working in space flight...

    Carbon fiber layups depend on the correct epoxy to give them strength. If that epoxy is too brittle or lack ductility on impact it can fracture. A crack in the matrix (the carbon fiber is the reinforcement) will lead to eventual failure of the composite. As far as I know, acrylics/enamels like finger nail polish won't cut the mustard in this application. Hence their usage in decorating finger nails. I would think that they would do a cosmetic "repair" only. Any significant removal of the matrix (epoxy) will lead to a break down of the composite and eventual failure.

    Many of today's CF composites use ballistic grade epoxies, meaning that the material can take an impact without fracture. I am unsure if Yeti was using such a material in '08. However, I would assume that they use it now (but I would still call and find out). The Mojo HD has such a matrix material and as a result is very impact resistant (read the Ibis forum and try to find a thread about a failed frame...there are very few). A good example of this application is a carbon wheel. The wheel is right down there in the thick of it and the guarantees for strength and damage resistance are no questions asked (by both ENVE and Easton, I believe). So, take that for what it is I guess.

    $.02 done...
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  7. #7
    jddist
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    Carbon Free zone here also. Like eatdrinkride I live in phoenix and this place eats bikes. On top of that, Yeti doesn't have a real good reputation for having a durable carbon solution. Every single person I know or have met on the trails out here that rides a 575 have broken at least one carbon rear tri. I went through 2 before moving onto a 7, my riding partner went through 2 as well. If you ride in an area with lots of rocks I would stay with carbon, unless the manufacture offered a no questions asked FREE replacement policy. As for the 66c, it will take some time to tell if that carbon implementation is more durable than the 575 stuff.

  8. #8
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    Quote Originally Posted by snigs View Post
    Um, this will not save you from a failure. As a friendly word of advice have a shop check it out.

    ..
    Never said it would. Just makes it look better so I don't get so pissed every time I see it.

    I will not pay a 'shop' or anyone else to 'look' at my frame. I don't bother babysitting my bike and when and if it fails, or even if it doesn't, it will be the last cf on any part of my frame I ever ride in AZ.

  9. #9
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    The new ballistic carbon is way more durable and impact resistant than AL. Any impact that takes a chunk out of the carbon would also leave a huge dent in AL. Also remember that the top layer of carbon is typically cosmetic and not structural. There are plenty of these types of threads on both the SC and Ibis forums.

    So You Thought Carbon Fiber Was Fragile?

    I ride carbon and live in Socal which is rock city. Plenty of strikes and not one issue.

  10. #10
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    The new ballistic carbon is way more durable and impact resistant than AL. Any impact that takes a chunk out of the carbon would also leave a huge dent in AL.
    I call BS on this one. From experience, and lots of it...riding in rocky terrain is brutal on CF. The fall off the side of my bike a few weeks back that chunked out the CF on my stay would have left no damage to an Al stay, except for a scratch maybe. It's not the impact force that did the damage as there was almost none, it was the sharp corner of a granite rock that did the trick.

    Anyhow it's a stupid point to argue as you obviously (and everyone who loves cf) don't ride where I do, so your view, as well as mine, are subjective. I mean, saying new ballistic carbon is "WAY" more durable and impact resistant than Al is hardly quantifiable, and if you rode South Mtn. every day I promise you would not be touting cf so highly.

  11. #11
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    Quote Originally Posted by eatdrinkride View Post
    I mean, saying new ballistic carbon is "WAY" more durable and impact resistant than Al is hardly quantifiable, and if you rode South Mtn. every day I promise you would not be touting cf so highly.
    I agree with you there, I have been on the National Loop at South Mountain many times and it's down right nasty. I love riding in Phoenix, wish I lived closer.

  12. #12
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    I'm in the midwest, so rocks and granite are not a common occurance. Most of the rock gardens around here have to be built. It's rare that you crash here and land on rocks - more hard dirt and/or roots. Small loose rocks can kick up some. It sounds like a lot of you choose aluminum based on location and potential damage/maintenance more so than actual performance characteristics of the material. Here in the midwest, I shouldn't have to worry about that as much.

    So I'm probably trying to decide more about the way one rides vs the other. I'm assuming that a complete carbon frame behaves quite differently than a full aluminum or carbon rear only like my 575.

    My 575 is 3.5 yrs old and essentially scratch free. I ride hard, but i'm meticulous about maintaining my bike. With that said, I did have a problem with the carbon rear tri once. And not from a crash or impact. But since then, I don't think about it when I'm riding.

    looking at the 66, it appears to be structurally far more beefy and significant. Just the tubing alone looks much more substantial than the carbon 575 rear. But as far as how the carbon is made now vs then, does any one really know? I would assume just like anything else, things have evolved.

  13. #13
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    I think people tend to hype up stuff a bit too much. I mean you've heard all the talk of "improved damping" with CF bars and blah blah blah. I rode CF Monkylite bars for years. Switched a year ago to Answer Al bars, couldn't tell a bit of difference between the two. My buddy has an '07 Enduro I've ridden several times. When Speshy was out here in '08 or '09 he demo'd a full CF Enduro at SoMo. I rode it for a bit. Felt much like his bike but lighter and more responsive and less confidence inspiring in the rough. (read...much lighter spec and frame)

    Buy whatever is calling you, enjoy it and don't fret about it. Sounds to me like you are ready for a CF frame

  14. #14
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    I can't speak for the 66, but I had the same concerns moving to a ASR5C. It was my first carbon bike, and I had read on this forum about the seatstays cracking etc. I was a bit of a doubter and held my breath when I placed my order and on my first few rides. Well, I rode it hard all year - trail riding, stage race, xc racing - had plenty of crashes (and some of the worst crashes I've ever had). And I'm about 200 lbs. Not one problem. I did use frameskin, and I think that helps with scratches etc. But carbon is tougher than a lot of us give it credit for. That said, as others have suggested, if you ride in really rocky terrain, where you will have plenty of rock strikes, then it might be worth going with aluminum. But it sounds with your type of terrain you will be plenty fine with the carbon model. The stiffness and light weight are definitely noticeable - not earth-shatteringly so, but you can tell.

  15. #15
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    Thanks for the input chunky, that's very helpful as are all these replies. Sounds like you had some of my same initial hesitations. Yeti has a few years of carbon under their belt now and it would seem (from following this forum for years) like they've gotten better at it. Actually all their bikes have improved and progressed in general - which is what I would expect from my favorite maker of shred sleds.

    Just getting on here and discussing it can make things more clear or light bulbs come on. I know it won't be night and day, but I do expect to notice a slight difference in small details with the carbon. I'll notice more of a difference in the jump from 575 to SB than Al vs carbon. The older I get, the more I look for the most advanced and capable tool for the job as long as I can afford it. I enjoy being the only limitation on my bike

  16. #16
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    Good question as I haven't ridden the 66c obviously. But just recently built up a 66a and have been hammering it on my favorite local AM trails and the frame feels a little on the heavy side as compared to another slightly lighter AM frame it replaced. The feeling of extra weight in the frame does make it feel more solid and sure footed landing jumps and bombing down rough trails, but think if you after a more nimble, lighter handling trail/AM bike and plan to do some competiive racing with it (Super D's), the carbon version might be best way to go. Is it worth the extra 800 bones? Don't know, only you can answer that. I went Alu since roughly $2500 or so was my total build budget (using mostly pre-existing parts) and think I should be a on a little stouter frame then what I was on before (broke my last two AM frames in 1.5yrs), especially for more aggro type of riding.
    Ride On!

  17. #17
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    Quote Originally Posted by eatdrinkride View Post
    I call BS on this one. From experience, and lots of it...riding in rocky terrain is brutal on CF. The fall off the side of my bike a few weeks back that chunked out the CF on my stay would have left no damage to an Al stay, except for a scratch maybe. It's not the impact force that did the damage as there was almost none, it was the sharp corner of a granite rock that did the trick.

    Anyhow it's a stupid point to argue as you obviously (and everyone who loves cf) don't ride where I do, so your view, as well as mine, are subjective. I mean, saying new ballistic carbon is "WAY" more durable and impact resistant than Al is hardly quantifiable, and if you rode South Mtn. every day I promise you would not be touting cf so highly.
    Yeah no rocks in CO

    As far as "quantifiable" you ought to look up the definition of that word...

    web.mit.edu/course/3/3.91/www/slides/cunniff.pdf
    Carbon Fibre Reinforced Plastic (CFRP) | Ingenieurparadies
    Why CFRP? : Composites World

    And these are just a few of the resources. I know I'll never change your opinion, but I won't let ignorance rule...knowledge trumps belief.
    Last edited by snigs; 12-15-2011 at 12:11 PM. Reason: fixed dead link
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  18. #18
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    Quote Originally Posted by Salespunk View Post
    So You Thought Carbon Fiber Was Fragile?

    I ride carbon and live in Socal which is rock city. Plenty of strikes and not one issue.
    Probably a crack in the paint. Most likely the composite flexed and returned to its original shape...
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  19. #19
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    Quote Originally Posted by snigs View Post
    Um, this will not save you from a failure. As a friendly word of advice have a shop check it out.

    My credentials? Mechanical engineer (MS Solid Mechanics) working in space flight...

    Carbon fiber layups depend on the correct epoxy to give them strength. If that epoxy is too brittle or lack ductility on impact it can fracture. A crack in the matrix (the carbon fiber is the reinforcement) will lead to eventual failure of the composite. As far as I know, acrylics/enamels like finger nail polish won't cut the mustard in this application. Hence their usage in decorating finger nails. I would think that they would do a cosmetic "repair" only. Any significant removal of the matrix (epoxy) will lead to a break down of the composite and eventual failure.

    Many of today's CF composites use ballistic grade epoxies, meaning that the material can take an impact without fracture. I am unsure if Yeti was using such a material in '08. However, I would assume that they use it now (but I would still call and find out). The Mojo HD has such a matrix material and as a result is very impact resistant (read the Ibis forum and try to find a thread about a failed frame...there are very few). A good example of this application is a carbon wheel. The wheel is right down there in the thick of it and the guarantees for strength and damage resistance are no questions asked (by both ENVE and Easton, I believe). So, take that for what it is I guess.

    $.02 done...

    Yeti does say the 66 is High modulus, hand-laid carbon fiber. Is this what you are talking about? Is this different from what they used in '08?

  20. #20
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    I will be going with a carbon SB-66; already placed my order for one actually. Main reason: 1.5lbs lighter, stiffer, and looks better imo.

    I rode a 2010 ASR5C for a year and now have been on a 2011 575 for a year. I've put way more dents in the 575 aluminum frame from crashes, hitting trees, and rock strikes. The carbon ASR5 never dented or cracked despite hard crashes and lots of rock strikes. Sure there were chips in the clear coat, but other than that the ASR5 carbon held up better than the aluminum 575.

    I figure it's got a 2 yr warranty... if I bust the SB-66C it will most likely happen within that time-frame, and if it doesn't I'll be wanting the newest frame anyway a few years from now.

  21. #21
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    Quote Originally Posted by cwkrause View Post
    I figure it's got a 2 yr warranty... if I bust the SB-66C it will most likely happen within that time-frame, and if it doesn't I'll be wanting the newest frame anyway a few years from now.
    Cracking your frame from wrecks/spills/falls isn't covered under a warranty. You might qualify for a partial discount under crash replacement but that's discretionary on a case by case basis too.

    In my experience I have had worse luck with carbon than with aluminum.

  22. #22
    The Angry Singlespeeder
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    Carbon vs Al

    Although carbon might be less impact resistant than aluminum, once you kink, crimp or crack aluminum, it's structural integrity is permanently compromised.

    If a carbon fiber frame is cracked/damaged, in most cases it can be repaired to like new or stronger than new structurally. It's not cheap to do, but cheaper than buying a new frame.

    Example: On the way home from Singlespeed Cyclocross worlds, my aluminum Santa Cruz cross bike was on a rear bike rack, with the rack clamp on the top tube. On the freeway in the dark while driving 70 mph we accidentally hit a wheel lying in the road. The wheel hit the rear rack, twisting the frames in the clamp - my top tube is now mangled. See attached photo for only one of the several dents in the top tube.

    If it was carbon, I could have fixed it to look like it never happened. Not possible with aluminum.

    That's why I ride my Ibis Tranny through rock gardens without ever sweating it. Even if I lay it flat on a rock, I know I can fix it to be structurally like new.

    Sincerely,
    Attached Thumbnails Attached Thumbnails Pros and Cons of Al vs Carbon SB-66-carnage.jpg  

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  23. #23
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    Quote Originally Posted by swade View Post
    Yeti does say the 66 is High modulus, hand-laid carbon fiber. Is this what you are talking about? Is this different from what they used in '08?
    The modulus of a material is a constant that defines the proportionality between stress and strain. In other words: how much something deforms for a given load. "High" is just a category for strength:

    http://www.calfeedesign.com/tech-pap...-carbon-fiber/

    And just for fun

    Let me google that for you

    Overall impact strength has been improved by using matrix materials that are resistant to cracking, in conjunction with layup techniques.
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