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  1. #1
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    Carbon seatstays - why?

    This from "Ask RC" on the Mountain Bike Action magazine website:

    Q. Hi RC! I've noticed that a lot of mountain bikes are coming out with carbon seat stays. I would like to know what are their disadvantages over aluminum seat stays and if your bike has one, what can we do to protect them from damage. Thanks
    Erwin/mbaction.com - 6/14/2007 3:35:51 PM

    A. RC: I know I will incur some wrath here, but, of all the stupid places to use carbon fiber, the seatstay of a mountain bike is the dumbest yet. Does it save weight? No, not unless the previous aluminum stay was poorly designed. Composites are weakest in compression--exactly what the major stresses are on a seatstay. A paper-thin aluminum stay would do a better job and for less money. Basically, it's the easiest place for a bike maker to put carbon where its customers will see it and say "Wow, that is cool."

    Now I know that many people do not agree with a lot of Richard Cunninghame's ideas BUT I tend to agree with the statement above.
    Not sure why the new ML frame has to have carbon seatstays?
    Purely bling factor?
    Marketing hype following the "carbon is cool" trend?
    Just my 2c
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  2. #2
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    I'd tend to agree as well while having a few different opinions. Carbon on the stays is silly but I'd say carbon on the chain stays would be the dumbest yet with seat stays a distant second. I also don't think strength of composite is really that much of an issue on a seat stay but apparently the bonding AL to Carbon is an issue.

    I have a Racer X, not an ML but I would definitely welcome an all AL rear triangle option.
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  3. #3
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    Agree..

    Everyone should inspect the nicks, scratches, & dings on their 1+ yr old aluminum seatstay and chainstay. Imagine if it was made out of a carbon. When I fall, I don't fall pretty, and frame take quite the beating as it rams into the rock and boulder. Carbon bits on frame, I just don't get.
    sth

  4. #4
    the 36 year old grom
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    I think the best place to use carbon on a bike is almost everywhere…..

    In regards to motive…
    My guess as to why the seat stay is a popular place to add carbon is the cost of the part. Its already a complex weldment and probably “expensive” to begin with. Probably a cost effective place to add a carbon part.

    and on the ML is saves 75g

  5. #5
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    Replacement seat-stay

    My 2005 AL seat-stay cracked and Titus warranted the part with their new CF one. I was a bit surprised to say the least when I got it since I was expecting the polished AL variety.

    Well, it is rather sexy and I'm more than happy to give it a beating. Granted, I haven't crashed on it yet, but all is well so far. I do worry about that inevitable crash, however. But, I just ride with the assumption that if it fails within a two year period, I'll just get it replaced again at no charge. Or if I crash it hard I can opt for the crash replacement policy.

    I just hope this isn't one of those material uses that are relegated to MTB infamy and puts me in the hospital.... or worse.

    P.S. The CS regarding this matter was excellent and I was taken care of in a very timely manner.

    Regards,

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  6. #6
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    I have a pre-production ML 2. It has the hydro-formed chain stays and carbon rocker, but still has the aluminum seat stays. Out of curiosity I emailed titus to see what the weight difference on the aluminum vs carbon stays is. They said that most of the weight savings on the ML 2 is actually from the hydro-formed chain stays. The carbon seat stays only make up about 55 grams of the difference.

  7. #7
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    I have just orderes an ML2 . Should I have gone for the alu version instead???? I might have time to change my order.

  8. #8
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    Quote Originally Posted by dareverend
    I have just orderes an ML2 . Should I have gone for the alu version instead???? I might have time to change my order.
    no dood

    take your CF one's off

    all take my Alu ones off my bike

    we will swap them over and I will be happy

    i have broke 3 Alu seat or chainstays on 3 different bikes

    Alu rares and their supposed durability are not all their cracked up to be

  9. #9
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    Quote Originally Posted by dareverend
    I have just orderes an ML2 . Should I have gone for the alu version instead???? I might have time to change my order.
    I agree with AM, stick with the ML2 ... Put me next priority if you want to swap... next to AM of course

  10. #10
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    thanks fellas.got a bit twitchy when i started reading this thread. can now sleep tonight.

  11. #11
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    Sleep easy, I wanted one when I was at Titus last week, none in stock....

    Sheesh, What about the Scott Ransom Ltd, that is all carbon, no readings on that shiating its pants.....
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  12. #12
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    Quote Originally Posted by Whafe
    Sheesh, What about the Scott Ransom Ltd, that is all carbon, no readings on that shiating its pants.....
    You mean that bike that breaks at the downtube by the BB and uses a leverage ratio of like 4:1???

    No, thank you, sir...
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  13. #13
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    Quote Originally Posted by Warp
    You mean that bike that breaks at the downtube by the BB and uses a leverage ratio of like 4:1???

    No, thank you, sir...
    The_Lecht_Rocks: whafe - cheeers - may i offer an official apology for the wagon wheeler "dis-belief"

  14. #14
    thats right living legend
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    Quote Originally Posted by Whafe
    Yeah Whafe you "somehow" picked the exact WRONG bike to hold up as an example of of carbon fiber depenabiliity.

  15. #15
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    You forget that Titus (and other manufacturers) have been making bikes for quite a while, and they are experts at the process. The image that CF is a weak material is false in so many ways. I bet it would take a hard pounding for those things to break...

    Leave the design and structural integrity problems to Titus...just enjoy what you have!

  16. #16
    the 36 year old grom
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    ".....Composites are weakest in compression--exactly what the major stresses are on a seatstay...."

    so I wonder what RC says about carbon seat posts. the loading on a seat post is also mostly compression....

  17. #17
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    Quote Originally Posted by demo_slug
    so I wonder what RC says about carbon seat posts. the loading on a seat post is also mostly compression....
    ... only on one side...


    Oddly enough, many hardtails and road bikes have carbon seatstays.
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  18. #18
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    Makes me laugh, when it seems that many think that no companies do any research. Sheesh, when I am on my road bike, which is all carbon at 80kmh downhill, I am not thinking about R Cunningham's comments re carbon being weak as piss etc.... Man alive, the world is full of balloon prickers...

    Go the carbon..................Each to there own though...
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  19. #19
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    Quote Originally Posted by Warp
    Oddly enough, many hardtails and road bikes have carbon seatstays.
    Isn't this done to improve ride quality? Carbon fiber can absorb high frequency vibration very effectively so making the fork and seatstays out of carbon fiber prevents some of this vibration from being transfered to the rider.

    Quote Originally Posted by RC
    Composites are weakest in compression--exactly what the major stresses are on a seatstay. A paper-thin aluminum stay would do a better job and for less money.
    True, single ply carbon fiber is weaker in compression due to microbuckling of the fibers. I would still have to see some cyclic testing results to believe a multi-ply carbon seatstay is weaker than an aluminum seatstay of equivalent weight.

  20. #20
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    Quote Originally Posted by Blofeld


    True, single ply carbon fiber is weaker in compression due to microbuckling of the fibers. I would still have to see some cyclic testing results to believe a multi-ply carbon seat stay is weaker than an aluminum seatstay of equivalent weight.

    It is my belief that carbon is indeed stronger than al pound for pound, but isn't the concern more directed towards scratches and nics compromising the integrity of the entire stay in regards to CF.

  21. #21
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    Quote Originally Posted by Blofeld
    Isn't this done to improve ride quality? Carbon fiber can absorb high frequency vibration very effectively so making the fork and seatstays out of carbon fiber prevents some of this vibration from being transfered to the rider.
    Yeah, bro... That was my point. In a HT, the seatstay has to suck up the hits, big or small. On a FS, it "only" pushes the shock.



    Quote Originally Posted by Blofeld
    True, single ply carbon fiber is weaker in compression due to microbuckling of the fibers. I would still have to see some cyclic testing results to believe a multi-ply carbon seatstay is weaker than an aluminum seatstay of equivalent weight.
    Yeah, carbon is much like wood in the sense that it depends how the fibers are laid to provide certain stress characteristics.

    RC may have a point in the sense that weight savings are not huge and that Al is cheaper... but I agree the most with Whafe, to each their own.

    As for me, I worry about impacts. I recently managed to bust a brake lever. Totally my fault. Certainly, there are materials that are not made for cavemen like me. It's something I don't want to worry about.
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  22. #22
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    Quote Originally Posted by Blofeld
    Isn't this done to improve ride quality? Carbon fiber can absorb high frequency vibration very effectively so making the fork and seatstays out of carbon fiber prevents some of this vibration from being transfered to the rider.
    I am of the strong opinion that it's done primarily for marketing purposes, not for ride tuning. Using a traditional 32-spoke wheel instead of a 24-spoke deep rim design will yield a smoother ride than slapping CF seat stays on an aluminum/steel/titanium road frame.

    As to the dis/advantages of using CF on the ML, time will tell.
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  23. #23
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    Quote Originally Posted by blackagness
    It is my belief that carbon is indeed stronger than al pound for pound, but isn't the concern more directed towards scratches and nics compromising the integrity of the entire stay in regards to CF.
    I think this is the legitimate concern with carbon fiber parts, even if in some circumstances having several distinct layers and fibers will prevent a crack from growing. I guess I didn't read that into RC's reply in the OP.

    Quote Originally Posted by Warp
    Yeah, bro... That was my point. In a HT, the seatstay has to suck up the hits, big or small. On a FS, it "only" pushes the shock.
    Quote Originally Posted by pinkrobe
    Using a traditional 32-spoke wheel instead of a 24-spoke deep rim design will yield a smoother ride than slapping CF seat stays on an aluminum/steel/titanium road frame.
    How much of the spectrum do you think overlaps between the shock, wheels/tires and seatstays in terms of frequencies absorbed?

  24. #24
    the 36 year old grom
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    Quote Originally Posted by pinkrobe
    I am of the strong opinion that it's done primarily for marketing purposes, not for ride tuning. Using a traditional 32-spoke wheel instead of a 24-spoke deep rim design will yield a smoother ride than slapping CF seat stays on an aluminum/steel/titanium road frame.

    As to the dis/advantages of using CF on the ML, time will tell.
    Time will tell. Nice thing about MTBR is that us consumers get to see/ hear about how all these things break.

    the weak link on the ML has been the aluminum chain stay. they break at the welds.... people been breaking titus seat stays for a long long time, its not just the MotoLite BTW.

    IMHO the whole material argument is silly because this stuff almost always break at a joint. at a weld or a bond. so let the most fatigue resistant joint win!!!

    and firmly disagree that the ML seat stay is "marketing". I have high hopes that they will make the ML stronger and longer lasting.

  25. #25
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    Quote Originally Posted by pinkrobe
    As to the dis/advantages of using CF on the ML, time will tell.
    Here here, pinkrobe has it totally correct here.....Time will tell!

    I am not having any issues with the carbon moulded into my Ti downtube though.
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  26. #26
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    What many people don't realize is how incredibly hard the resin is that they use to set the fiber cloth, which is subsequently baked and made even harder. The resin becomes VERY abrasion resistant. This doesn't mean that any impact won't cause damage, as you only need significant force and a couple other factors to do it. I am less concerned about the compression in stays, but more concerned about the lateral flexing and abrasion. Yeti has made a carbon layered stay inside a tube, which seems to be a good compromise. Otherwise, exposed carbon, no matter how hard the resin is, should not be used. Direct impacts aside, abrasions over its life are a real prospect and again, the resin is extremely hard, but not 100% impervious to all abrasions.

  27. #27
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    I'm with ya... sort of...

    Quote Originally Posted by Jerk_Chicken
    Otherwise, exposed carbon, no matter how hard the resin is, should not be used. Direct impacts aside, abrasions over its life are a real prospect and again, the resin is extremely hard, but not 100% impervious to all abrasions.
    My heart agrees with The Jerk's philosophy here, but my head is more objective. Only until a good statistical population of CF stays are in use and on the trails will we really know both the good and the bad. Now, I've seen on mtbr CF stays fail at the bond, but I'm totally unaware of a failure due to an external abrasion.

    This does beg the question: How much damage can CF seat-stay sustain before it fails?

    EDIT: I went to the Ibis board to snoop around and I didn't find posts regarding broken CF stays or frames for that matter. However, there is a certain level of concern about abrasions.

    Regards,

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  28. #28
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    IMO carbon on any part of a MTB frame is not good unless you are building a superlight racebike, and even then beware of it's limitations. due to the brittleness of the material it just doesn't make any sense

  29. #29
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    Quote Originally Posted by salimoneus
    IMO carbon on any part of a MTB frame is not good unless you are building a superlight racebike, and even then beware of it's limitations. due to the brittleness of the material it just doesn't make any sense
    OT, Hi Sal... Hows it goin? have not heard from you here in the forum lately....

  30. #30
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    given similar force (alu vs ca; at same weight), alu would break first.
    However, carbon breaks with no warning / sign.
    Thus, if made right, it is the one to get.

    2 weeks ago Robert Kubica of BMW F1 team crashed in Gilles Villeneuve circuit in Canada. The car spun several times in the air. Yet the cockpit, made of carbon composite, was untouched.
    2 (?) years ago, Ralf Schumacher had ugly crash in Indianapolis, at the oval section. All crushed, but the cockpit was, again, left untouched.

    Imagine if they were made of Aluminum..

  31. #31
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    If I was a bicycle company then I would love to make as many products as possible in my line out of CF,you just can`t beat that kind of profit with things that are that sensitive to damage (while somehow still being promoted and perceived as strong) like scratches.But because I`m a consumer (and not one who embraces disposable culture),I will avoid using CF for MTB.Look at ANY bicycle that is used regularly after a year,you will not find one without scratches or some kind of impact on the frame.
    For the F1 example that was mentioned earlier,yes the cages in the race cars are strong but all they have to work is once.Will you throw your bike or part out after every crash and buy a new one?
    Last edited by yoginasser; 06-20-2007 at 02:11 AM.
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  32. #32
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    I don't think there is anything structurally wrong with the carbon seatstay and it does save weight. So as usually, the "expert" RC has no idea what he's talking about. However, I don't think the carbon stay is worth the $400 upcharge for the MLII over the previous model.
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  33. #33
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    corrosion

    I'm on the side that believes that the geomtery and design of the CF stays can be manipulated to make CF work without issue of breakage under ideal conditions.

    However, my biggest concern about the trend of fusing and mating Carbon Fiber with Aluminum is galvanic corrosion between the two materials. Carbon Fiber and Aluminum are very dissimilar on the galvanic scale. Basically, the farther away two joined materials are on this scale, the more corrosive the interface. After time and exposure to sweat (or salt water) CF will eat away at Aluminum and I can't believe that Titus, or anyone else, would consider the weakened condition caused by corrosion during the design of the materials/interface to provide sufficient strength in the worst case.

    So far I've found two cases of galvanic corrosion between Al and CF on bikes - and I haven't been actively searching:

    1) I found corrosion occuring between my CF seatpost and my RX Alumium frame after six months of not being removed. If you see a white powder that is the evidence of corrosion. I was also suspicious when I tried to adjust the seat post but it wouldn't move after I loosened the collar. I had to hit the nose of the seat hard to break it loose. I take responsibility for neglecting to maintain the interface in this case but my point is that there was corrosion occuring.

    2) I recently looked at buying a lightly used 2006 model road bike that had fused CF with Aluminum (giving full benefit of the doubt to the manufacturer who I thought was probably ahead of me on this issue). Sure enough I could see there were signs of corrosion at the mating points even with the clear coat of paint. Luckily, I got to see this bike in person before deciding whether or not to buy it. I couldn't imagine a mating joint failure while riding!

    From my limited knowledge from engineering metallurgy 101 class, seeing this in action on my bike, and almost purchasing a bike with this issue thats enough evidence for me to completely avoid any frame that fuses or mates CF to Al in any way. I also got rid of my CF seatpost. For me, I'll stick with Al on Al and suffer the weight or stiffness penalty.

    As a side note, I recall Ti and CF are similar on the galvanic scale so the likehood of these issues occuring on something like exogrid is probably small. I'll need to dust of my metallurgy text book for more info...

    fro

  34. #34
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    Wow

    Thank you Jeffro,good stuff.
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  35. #35
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    Quote Originally Posted by yoginasser
    Thank you Jeffro,good stuff.
    I've been doubting my concerns for a couple of years now but after seeing it first-hand I'm a believer.. I guess time will tell if this is an issue on the stays. Thankfully, I have a 2004 with Al stays - no problems.

  36. #36
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    Quote Originally Posted by yoginasser
    If I was a bicycle company then I would love to make as many products as possible in my line out of CF,you just can`t beat that kind of profit with things that are that sensitive to damage (while somehow still being promoted and perceived as strong) like scratches.But because I`m a consumer (and not one who embraces disposable culture),I will avoid using CF for MTB.Look at ANY bicycle that is used regularly after a year,you will not find one without scratches or some kind of impact on the frame.
    For the F1 example that was mentioned earlier,yes the cages in the race cars are strong but all they have to work is once.Will you throw your bike or part out after every crash and buy a new one?
    for the CF ~ Bike company analogy. I would add that, not only CF rings "higher price" (so a company can charge more as well), but also that CF is "in momentum" (CF insert, CF seatstays, CF rocker arm, etc). A company do not want to lose momentum of gaining more profit & market share.

    As for the scratches thing: warranty obviously does not apply for mis-application. Yet, if the scratches causing the "thing" to fail, then logically it should be honored by the warranty. What I was trying to say: given similar force to similarly weighted CF & Al, CF can take it better than Al. If the product made of CF fails, then the Al version will most certainly fail earlier, provided that both has correct construction (and not just weight saving in mind). Thus, in the case of CF part surviving accident & re-using it, then my take is: if it was made of Al, it would be badly dented & not usable, either. Just my opinion

    As for F1: Crashing the car at hundreds mph, I dont think re-using such cockpit is wise.

    To sum it up: it all depends on cost, and ongoing technology.

    Nice sharing session

  37. #37
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    Quote Originally Posted by paneristi
    given similar force (alu vs ca; at same weight), alu would break first.
    However, carbon breaks with no warning / sign.
    Thus, if made right, it is the one to get.

    2 weeks ago Robert Kubica of BMW F1 team crashed in Gilles Villeneuve circuit in Canada. The car spun several times in the air. Yet the cockpit, made of carbon composite, was untouched.
    2 (?) years ago, Ralf Schumacher had ugly crash in Indianapolis, at the oval section. All crushed, but the cockpit was, again, left untouched.

    Imagine if they were made of Aluminum..
    For those that didn't see it, HERE it is. He was going about 275kph / 170mph when he hit that wall. Realesed from the hospital the next day with a broken leg. Amazing.

  38. #38
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    on the bright side(providing a nasty accident is avoided). brocken stays mean a possible upgrade.... the wife can't argue with damaged equipment.

  39. #39
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    Quote Originally Posted by jeffro
    I'm on the side that believes that the geomtery and design of the CF stays can be manipulated to make CF work without issue of breakage under ideal conditions.

    However, my biggest concern about the trend of fusing and mating Carbon Fiber with Aluminum is galvanic corrosion between the two materials. Carbon Fiber and Aluminum are very dissimilar on the galvanic scale. Basically, the farther away two joined materials are on this scale, the more corrosive the interface. After time and exposure to sweat (or salt water) CF will eat away at Aluminum and I can't believe that Titus, or anyone else, would consider the weakened condition caused by corrosion during the design of the materials/interface to provide sufficient strength in the worst case.

    So far I've found two cases of galvanic corrosion between Al and CF on bikes - and I haven't been actively searching:

    1) I found corrosion occuring between my CF seatpost and my RX Alumium frame after six months of not being removed. If you see a white powder that is the evidence of corrosion. I was also suspicious when I tried to adjust the seat post but it wouldn't move after I loosened the collar. I had to hit the nose of the seat hard to break it loose. I take responsibility for neglecting to maintain the interface in this case but my point is that there was corrosion occuring.

    2) I recently looked at buying a lightly used 2006 model road bike that had fused CF with Aluminum (giving full benefit of the doubt to the manufacturer who I thought was probably ahead of me on this issue). Sure enough I could see there were signs of corrosion at the mating points even with the clear coat of paint. Luckily, I got to see this bike in person before deciding whether or not to buy it. I couldn't imagine a mating joint failure while riding!

    From my limited knowledge from engineering metallurgy 101 class, seeing this in action on my bike, and almost purchasing a bike with this issue thats enough evidence for me to completely avoid any frame that fuses or mates CF to Al in any way. I also got rid of my CF seatpost. For me, I'll stick with Al on Al and suffer the weight or stiffness penalty.

    As a side note, I recall Ti and CF are similar on the galvanic scale so the likehood of these issues occuring on something like exogrid is probably small. I'll need to dust of my metallurgy text book for more info...

    fro
    Good stuff, bro!!

    Somewhere I read this about galvanic corrosion on Al-CF joints and some (most??) manufacturers use a layer of fiberglass on top of CF at the joints to prevent this.

    As consumers get more and more informed, it would be a good marketing point, so to speak... as long as this is true.

    Same as we do on field with dissimilar galvanic materials, put an insulator in the middle. For example when using plain carbon steel bolts on stainless joints. You put insulators in.



    On kubica's crash... he didn't even had a broken leg. It was just a strained ankle. Amazing. I didn't watch the race, but when I saw the accident's clip, I got chills.... Some drivers have died for less than that. Schumacher's crash when he broke a leg was much less serious.
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    Quote Originally Posted by Warp
    Good stuff, bro!!

    Somewhere I read this about galvanic corrosion on Al-CF joints and some (most??) manufacturers use a layer of fiberglass on top of CF at the joints to prevent this.

    As consumers get more and more informed, it would be a good marketing point, so to speak... as long as this is true.

    Same as we do on field with dissimilar galvanic materials, put an insulator in the middle. For example when using plain carbon steel bolts on stainless joints. You put insulators in.



    On kubica's crash... he didn't even had a broken leg. It was just a strained ankle. Amazing. I didn't watch the race, but when I saw the accident's clip, I got chills.... Some drivers have died for less than that. Schumacher's crash when he broke a leg was much less serious.
    I know that's true - that you can mitigate the corrosive effects of dissimilar materials using a third material in between two dissimilar materials but to my knowledge this isn't used in Titus's stays (I took a tour of Titus a couple of years ago when they started this cf stay thing and asked that question - without much of a response). Maybe they have changed the design?? I dont' know
    A third material definitely didn't appear to be used in the cannondale road bike I looked at either. If it was being used it was completely ineffective.

    So, that's scary for me that the bike companies either don't know much about galvanic corrosion or they simply choose not to prevent the issue with a design countermeasure.

    By the way, I sat amongst a large crowd of very dissapointed Polish people at Indianapolis on Sunday. I tried not to show too much excitement that Hamilton won for fear of being beaten with flagpoles..Thankfully, Kubica is alright.

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    Quote Originally Posted by jeffro
    I know that's true - that you can mitigate the corrosive effects of dissimilar materials using a third material in between two dissimilar materials but to my knowledge this isn't used in Titus's stays (I took a tour of Titus a couple of years ago when they started this cf stay thing and asked that question - without much of a response). Maybe they have changed the design?? I dont' know
    A third material definitely didn't appear to be used in the cannondale road bike I looked at either. If it was being used it was completely ineffective.

    So, that's scary for me that the bike companies either don't know much about galvanic corrosion or they simply choose not to prevent the issue with a design countermeasure.

    By the way, I sat amongst a large crowd of very dissapointed Polish people at Indianapolis on Sunday. I tried not to show too much excitement that Hamilton won for fear of being beaten with flagpoles..Thankfully, Kubica is alright.
    Either the bonding or the resin used can have these corrosion protection characteristics, but either they don't know about it or they don't use it. I don't know. So I will not argue if they use it or not. You seem to have a much clearer idea.

    Yeah, thankfully Kubica's OK and hamilton goes ahead of a*hole Alonso... As long as it's Hamilton, the Maccas can be ahead of Ferrari, no problem. Tifosi here.
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    Umm, hasn't the racer-x been using carbon seatstays for quite awhile now with no reported breakages other than maybe a joint or two coming unglued. So, if this is the case why all the concern about the stays on the motolite? I think Titus knows what they're doing, and for that matter, Yeti as well. Why would a bike company intentionally put a rider at risk? That doesn't make sense. I think they saw the success of the stays on the racer-x and the breakage of the aluminum ones on the motolite and after testing came to the conclusion that the carbon ones would last longer even in the event of crashing in rocks. Titus is in Arizona after all.
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    Quote Originally Posted by Warp
    Either the bonding or the resin used can have these corrosion protection characteristics, but either they don't know about it or they don't use it. I don't know. So I will not argue if they use it or not. You seem to have a much clearer idea.

    Yeah, thankfully Kubica's OK and hamilton goes ahead of a*hole Alonso... As long as it's Hamilton, the Maccas can be ahead of Ferrari, no problem. Tifosi here.
    I'd like to add that maybe its unfair for me to come here and say that Titus doesn't consider corrosion in its design. I'm basing these comments on the blank looks I got when I asked the people at Titus a couple of years ago how they deal with corrosion there. that's all I'm going on here, nothing more.

    I am really shocked to have found that issue on a Cannondale bike. They sell a lot more bikes than Titus so I would think they would have their $hit together and they do claim to be the leader in "testing". but I guess this isn't something you'd necessarily learn on a shaker.
    Last edited by jeffro; 06-20-2007 at 10:47 AM.

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    This isn't a press fit is it?

    Quote Originally Posted by jeffro
    I'd like to add that maybe its unfair for me to come here and say that Titus doesn't consider corrosion in its design. I'm basing these comments on the blank looks I got when I asked the people at Titus a couple of years ago how they deal with corrosion there. that's all I'm going on here, nothing more.

    I am really shocked to have found that issue on a Cannondale bike. They sell a lot more bikes than Titus so I would think they would have their $hit together and they do claim to be the leader in "testing". but I guess this isn't something you'd necessarily learn on a shaker.

    I'd assume that whatever glue they use would be considered the "third material" in terms of galvanic corrosion.

    Dave

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    Consulted with a friend who makes exotic car frames from tubes and carbon fiber construction. He said there is no galvanic corrosion to be considered, nor has he ever seen any. The resin is the barrier, with the gloss coat being in between. For less flashy carbon fiber, they lose the gloss coat and they are working towards less and less resin, but the gloss adds impact resistance. There is still no galvanic corrosion to be considered, nor has he seen himself or heard of this in his years of building ($300k supercar).

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    Quote Originally Posted by Jerk_Chicken
    Consulted with a friend who makes exotic car frames from tubes and carbon fiber construction. He said there is no galvanic corrosion to be considered, nor has he ever seen any. The resin is the barrier, with the gloss coat being in between. For less flashy carbon fiber, they lose the gloss coat and they are working towards less and less resin, but the gloss adds impact resistance. There is still no galvanic corrosion to be considered, nor has he seen himself or heard of this in his years of building ($300k supercar).
    I did a general search and I found this link from calfee designs:

    http://www.calfeedesign.com/pdf/Calfee_TWP.pdf

    Calfee talks about galvanic corrosion as an issue when mating Al/CF on bike frames (page 10 on the link). Calfee also mentions a couple of other issues related to mating CF/Al (difference in Al/Cf thermal expansion properties, inadequate bonding).This document confirms my feeling that Cf/Al don't play well with eachother (but Cf/Ti do).

    I think it's really hard to compare frames on sports cars to those of bikes due to the different stresses and loads placed on them. I personally don't feel confident having an increased possibility of corrosion due to the above reasons, possibly affecting the integrity of frame in a high stress area with almost no way to visually detect it. From my experience and basic textbook knowledge of corrosion I'll pass on anything that mates Cf/Al and leave that for the gram saving people.

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    Quote Originally Posted by jeffro
    I did a general search and I found this link from calfee designs:

    http://www.calfeedesign.com/pdf/Calfee_TWP.pdf

    .
    1994 (up dated in 2002)? maybe bonding technology has changed in the last decade?

    anyway... lots of neat phyics stuff...

    I would take the calfee white paper with a grain of salt...the calfee paper seams to be aimed at why his frame is better to the lugged carbon road bikes of the day.

    Which is interesting as a side note, titus has the moderna which is a lugged carbon bike. so maybe titus/vaytek have no idea how to play with carbon. or maybe they do know something about carbon.

    seems there is some alu on carbon action on roady forks too...


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    Odd I was always under the impression that for the galvanic action you needed some type of
    electrolyte between the metals (usually what is involved) for the ions to pass through. Thus always greasing the al seatpost on steel frames (well any frame really), which is
    the usual place that this is seen (or at least a stuck seatpost is all that I have seen personally)

    I would think that the resin and bonding agents would be enough to stop this.
    In the case of a seatpost you would think that the grease or carbon paste would be enough to stop this.

    In the al-carbon junction which is the anode and which is the cathode (what is being eaten away)?

    going to have to do a bit of searching this evening....

    Not that this reallt effects me as I have no carbon on my motolite.....

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    I looked at Titus website and I couldn't find a Cf/Al lugged roadbike in the bunch.. it seems they don't sell the Modena any longer. titus only offers lugged Cf/Ti road bikes now. maybe this is related or simply a coincidence. I don't know

    Maybe Titus/Vyatec does know something about Cf bonding but I really didn't get that feeling when I asked them about corrosion at the joints. They were able to explain ad nauseum about the suspension behavior, fit, fork compatibility.. but didn't have any answer about their material compatibility. Incidentally, I also looked at their prototype Modena on that same visit which also raised the question.

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    Quote Originally Posted by esilvassy
    Odd I was always under the impression that for the galvanic action you needed some type of
    electrolyte between the metals (usually what is involved) for the ions to pass through. Thus always greasing the al seatpost on steel frames (well any frame really), which is
    the usual place that this is seen (or at least a stuck seatpost is all that I have seen personally)

    I would think that the resin and bonding agents would be enough to stop this.
    In the case of a seatpost you would think that the grease or carbon paste would be enough to stop this.

    In the al-carbon junction which is the anode and which is the cathode (what is being eaten away)?

    going to have to do a bit of searching this evening....

    Not that this reallt effects me as I have no carbon on my motolite.....
    I'm guessing the magic is in the bond agent. but if this is broken somehow from cyclic fatigue or thermal cycling I think sweat or water both make for a really good electrolytes.

    Honestly, I don't recall everything about this. Its been a while since I took the class. I believe the material that is least noble would be corroded (anodic) and the most noble would be the corroder (cathodic). I'm pretty certain Al is close to being least noble and Cf would be almost the most noble - making for a bad fit.

    I need to get my book out when I get home. I hope I didn't sell it for post-exam beer money

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    Quote Originally Posted by jeffro
    I looked at Titus website and I couldn't find a Cf/Al lugged roadbike in the bunch.. it seems they don't sell the Modena any longer. titus only offers lugged Cf/Ti road bikes now. maybe this is related or simply a coincidence. I don't know

    Maybe Titus/Vyatec does know something about Cf bonding but I really didn't get that feeling when I asked them about corrosion at the joints. They were able to explain ad nauseum about the suspension behavior, fit, fork compatibility.. but didn't have any answer about their material compatibility. Incidentally, I also looked at their prototype Modena on that same visit which also raised the question.

    I think they don't make Aluminum road bikes anymore... All they have is carbon, Carbon-Ti and Exo-Shizzle.
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    Quote Originally Posted by jeffro
    Maybe Titus/Vyatec does know something about Cf bonding but I really didn't get that feeling when I asked them about corrosion at the joints. They were able to explain ad nauseum about the suspension behavior, fit, fork compatibility.. but didn't have any answer about their material compatibility. .


    I never got the feeling the Modena was a heavy seller. You can pick one up at Colorado cyclist for $799.

    Pop quiz??? Did you gather the complete design team for your QA session?

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    Quote Originally Posted by demo_slug


    I never got the feeling the Modena was a heavy seller. You can pick one up at Colorado cyclist for $799.

    Pop quiz??? Did you gather the complete design team for your QA session?
    No, it was the CEO, who I would have hoped did that already.

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    Quote Originally Posted by jeffro
    No, it was the CEO, who I would have hoped did that already.
    You are telling me that in you meeting with Pat Huas, he was not intimately familiar with any means of galvanic corrosion mitigation on his chain stay, even though he was given full warning of your visit and called a meeting to prepare to talk to you about it!!!!!

    You are right. Those guys most be clueless.

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    Quote Originally Posted by demo_slug
    You are telling me that in you meeting with Pat Huas, he was not intimately familiar with any means of galvanic corrosion mitigation on his chain stay, even though he was given full warning of your visit and called a meeting to prepare to talk to you about it!!!!!

    You are right. Those guys most be clueless.
    I'm not sure where you're coming up with all of your facts here.. I didn't name names for one, I didn't call any meetings. This wasn't a technical audit or anything. read through my previous posts.

    here I'll help you recap:
    I took a tour of Titus a couple of years ago (two maybe three years ago.. I don't remember the date). During the tour I saw the new RX stays w/ cf AND I saw a prototype Modena road bike. My first casual question was "how do you protect the two mating materials from corrosion?" if you think that inquiry warrants a full meeting with an entire design staff then you should think about the context of the question. I toured as a current owner of two new Titus bikes - a happy one at that. Moreover, I wasn't given a tour by the guy in the back building up bikes. The person in front of me signed off on these designs (I assume?) I didn't get a good answer.. I dropped the issue because I'm not a complete dick and I wasn't shopping for a road bike or new stays that day. I just let it go giving the benefit of the doubt. I think you need to read the title of this thread again. Carbon Seatstays - why?
    The original poster mentioned a magazine editor's reason for not liking the material choice...I'm giving one different reason 'why not' backed by science and my personal experiences. Sorry that doesn't jive with your biases.

    "pop quiz" do you think I would own two Titus bikes (my only two bikes) if I thought the company behind them was clueless?

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    Quote Originally Posted by jeffro
    I'm not sure where you're coming up with all of your facts here.. I didn't name names for one, I didn't call any meetings. This wasn't a technical audit or anything. read through my previous posts.

    here I'll help you recap:
    I took a tour of Titus a couple of years ago (two maybe three years ago.. I don't remember the date). During the tour I saw the new RX stays w/ cf AND I saw a prototype Modena road bike. My first casual question was "how do you protect the two mating materials from corrosion?" if you think that inquiry warrants a full meeting with an entire design staff then you should think about the context of the question. I toured as a current owner of two new Titus bikes - a happy one at that. Moreover, I wasn't given a tour by the guy in the back building up bikes. The person in front of me signed off on these designs (I assume?) I didn't get a good answer.. I dropped the issue because I'm not a complete dick and I wasn't shopping for a road bike or new stays that day. I just let it go giving the benefit of the doubt. I think you need to read the title of this thread again. Carbon Seatstays - why?
    The original poster mentioned a magazine editor's reason for not liking the material choice...I'm giving one different reason 'why not' backed by science and my personal experiences. Sorry that doesn't jive with your biases.

    "pop quiz" do you think I would own two Titus bikes (my only two bikes) if I thought the company behind them was clueless?

    The CF never touches the aluminum. The aluminum is anodized and the CF is coated in epoxy so both surfaces are fully protected. I just removed my carbon post from my Modena frame and there was also white residue but it was not galvonic corrosion since it's a CF post and a CF seat tube. More likely grit and epoxy mix.
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    Quote Originally Posted by jeffro
    I'm not sure where you're coming up with all of your facts here.. I didn't name names for one, I didn't call any meetings. This wasn't a technical audit or anything. read through my previous posts.

    here I'll help you recap:
    I took a tour of Titus a couple of years ago (two maybe three years ago.. I don't remember the date). During the tour I saw the new RX stays w/ cf AND I saw a prototype Modena road bike. My first casual question was "how do you protect the two mating materials from corrosion?" if you think that inquiry warrants a full meeting with an entire design staff then you should think about the context of the question. I toured as a current owner of two new Titus bikes - a happy one at that. Moreover, I wasn't given a tour by the guy in the back building up bikes. The person in front of me signed off on these designs (I assume?) I didn't get a good answer.. I dropped the issue because I'm not a complete dick and I wasn't shopping for a road bike or new stays that day. I just let it go giving the benefit of the doubt. I think you need to read the title of this thread again. Carbon Seat stays - why?
    The original poster mentioned a magazine editor's reason for not liking the material choice...I'm giving one different reason 'why not' backed by science and my personal experiences. Sorry that doesn't jive with your biases.

    "pop quiz" do you think I would own two Titus bikes (my only two bikes) if I thought the company behind them was clueless?
    Well where I think Demo is coming from is why in the world would "bike guy's/experts" that were giving you the tour have a clue about corrosive bonding techniques bla, bla bla. They've been doing it for a while as have several other companies why in the world would you assume any one of them doesn't know as much as you do about this stuff> After all they do feed their family and make their lively hood on this stuff. I personally have never heard of any one's cf/al bike corroding out from under them. Maybe what you saw wasn't corrosion? Maybe it was just resin erroding away under normal use or something. Either way what ever it was perhaps it's something completely normal?

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    Quote Originally Posted by Homebrew
    The CF never touches the aluminum. The aluminum is anodized and the CF is coated in epoxy so both surfaces are fully protected. I just removed my carbon post from my Modena frame and there was also white residue but it was not galvonic corrosion since it's a CF post and a CF seat tube. More likely grit and epoxy mix.

    We must have posted at the same time That's exactly what I was thinking but without your vocabulary.

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    Quote Originally Posted by barelylegal
    OT, Hi Sal... Hows it goin? have not heard from you here in the forum lately....
    [OT]
    hey bro...yea, i shamefully admit my lack of participation in both the forum and the sport the last couple months. i had some back issues, then i let the Vegas casinos and clubs tighten their grip on me ever so slowly. i tell ya livin here is a true test of discipline, which i used to think i had some amount of. must...escape...before...it's....too....late....

    actually heading up to Utah to do some camping/flyfishing/biking, lots of great trails to explore up there, lookin forward to it. maybe i should trade the ML for a Guap? hmmmm, i guess that's for another thread tho
    [/OT]

    carbon works wonderfully, in my fishing pole

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    Quote Originally Posted by salimoneus
    [OT]
    hey bro...yea, i shamefully admit my lack of participation in both the forum and the sport the last couple months. i had some back issues, then i let the Vegas casinos and clubs tighten their grip on me ever so slowly. i tell ya livin here is a true test of discipline, which i used to think i had some amount of. must...escape...before...it's....too....late....

    actually heading up to Utah to do some camping/flyfishing/biking, lots of great trails to explore up there, lookin forward to it. maybe i should trade the ML for a Guap? hmmmm, i guess that's for another thread tho
    [/OT]

    carbon works wonderfully, in my fishing pole
    EG is the way to go AM will be buying EG very soon too it will keep you away from those bright light machines there in Vegas ... it will make you escape and its not yet late ... good luck on your Camping/Fishing and most of all BIKING

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    Quote Originally Posted by blackagness
    Well where I think Demo is coming from is why in the world would "bike guy's/experts" that were giving you the tour have a clue about corrosive bonding techniques bla, bla bla. They've been doing it for a while as have several other companies why in the world would you assume any one of them doesn't know as much as you do about this stuff> After all they do feed their family and make their lively hood on this stuff. I personally have never heard of any one's cf/al bike corroding out from under them. Maybe what you saw wasn't corrosion? Maybe it was just resin erroding away under normal use or something. Either way what ever it was perhaps it's something completely normal?
    Yeah, the thing is I studied this subject for maybe 2 weeks in school and took an exam. I don't feed my family on this knowledge. Titus was showing me its breakthrough technology and I was simply asking how they got around what I knew to be some of the limitations (why something is a technology breakthrough in the first place). If you can't explain how you overcame a limitation then maybe its not really a breakthrough. Maybe they were keeping the knowledge to themselve - pending patent.. I don't know.
    There are plenty of companies that unsuccessfully try new things without proving them out.. why would Titus be immune to this? because of good marketing?

    who cares if it your stay breaks for whatever reason. I'm sure Titus would be happy to sell you a replacement in 3 years. Besides, these are lightweight race bikes and are designed to break at some point - as long as you know that going in.

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    Quote Originally Posted by salimoneus

    [OT]then i let the Vegas casinos and clubs tighten their grip on me ever so slowly.[/OT]

    carbon works wonderfully, in my fishing pole
    Trying to finance an EG by betting??

    This man has his priorities right!!!

    The car, the house, whatever...
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    Quote Originally Posted by jeffro
    I'm not sure where you're coming up with all of your facts here.. I didn't name names for one, I didn't call any meetings. This wasn't a technical audit or anything. read through my previous posts.
    here #1
    Quote Originally Posted by jeffro
    Maybe Titus/Vyatec does know something about Cf bonding but I really didn't get that feeling when I asked them about corrosion at the joints. They were able to explain ad nauseum about the suspension behavior, fit, fork compatibility.. but didn't have any answer about their material compatibility.
    "They" you said they. the whole tone of your post has been that "They" have not taken into consideration corrosion into the design of the carbon stays. and that they should have. and that you even you know better from your 101 class.

    Quote Originally Posted by jeffro
    No, it was the CEO, who I would have hoped did that already.
    the proof you offer is that the CEO of titus did not answer your questions to your satisfactions during a tour.

    Quote Originally Posted by jeffro
    I dropped the issue because I'm not a complete dick and I wasn't shopping for a road bike or new stays that day. I just let it go giving the benefit of the doubt
    I'm just pointing out that it is absurd to jump to that sort of conclusion, off a casual conversation. with one guy. especially given that you decided to air it out later in a open forum. so now you are complete. And you really didnít give them the benefit of the doubt.

    PS I don't know how you are not "naming names". because 95% of the guys around here know who the CEO is.... seems to get post every 2 or 3 weeks..

    although you are probably talking about the X president. but I'm not naming names.


    >>>>>>



    A good fun conversation about materials seems fun to me but you've crossed the line between good natured bike chatter and calling the design crap.

    sorry to come off as a heavy, but there you have it. at least I'm telling you now.

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    Quote Originally Posted by jetro
    Yeah, the thing is I studied this subject for maybe 2 weeks in school and took an exam. I don't feed my family on this knowledge. Titus was showing me its breakthrough technology and I was simply asking how they got around what I knew to be some of the limitations (why something is a technology breakthrough in the first place). If you can't explain how you overcame a limitation then maybe its not really a breakthrough. Maybe they were keeping the knowledge to themselve - pending patent.. I don't know.
    There are plenty of companies that unsuccessfully try new things without proving them out.. why would Titus be immune to this? because of good marketing?

    who cares if it your stay breaks for whatever reason. I'm sure Titus would be happy to sell you a replacement in 3 years. Besides, these are lightweight race bikes and are designed to break at some point - as long as you know that going in.

    I highly doubt any of the bike designers directly at Titus would have had anything to do with the development of any bonding techniques of cf and al or the exogrid technology. Vytech "how ever it's spelled" was most most likely behind that.

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    Quote Originally Posted by Blofeld
    Isn't this done to improve ride quality? Carbon fiber can absorb high frequency vibration very effectively so making the fork and seatstays out of carbon fiber prevents some of this vibration from being transfered to the rider.
    I'm with ya on this one...yeah there's some weight savings and yeah they probably are a bit stronger if not somewhat crash delicate. However, I believe the reason so many bike designers use Carbon Seat Stays and yeah, carbon forks, carbon bars, carbon seat posts is to reduce vibration and the resulting harshness of the ride.

    I know when I went from the Alu stays on my RXogrid to the newer carbon triangle the bike went to another level of "quietness" in its ride. The combo of the Exo and the Carbon rear is mind blowing in its smoothness.....like liquid chamois butter!!!
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    okay, I wasn't calling Titus's bikes crap. Based on my personal experience I have an opinion about the mating of cf/Al. Its different than yours. Get over it.

    I have a legitimate question related to the subject

    If the process of using cf seatstays reduces weight with no negative side effect to stiffness, durability, or impact resistance then why doesn't Titus use them on its RX 29er, El Guapo, or Supermoto? that seems inconsistent.

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    Quote Originally Posted by blackagness
    I highly doubt any of the bike designers directly at Titus would have had anything to do with the development of any bonding techniques of cf and al or the exogrid technology. Vytech "how ever it's spelled" was most most likely behind that.

    That's a possibility. There could be something spelled out contractually between Vyatech and Titus that keeps the IP out of Titus's hands. I could see Vyatech not wanting Titus to work around its IP. I think when the two companies started working together Vyatech only had a minority stake in Titus so it could have happened like that.

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    Quote Originally Posted by jeffro
    I have a legitimate question related to the subject
    never said you didn't.

    but you keep asking questions.

    Quote Originally Posted by jeffro
    If the process of using cf seat stays reduces weight with no negative side effect to stiffness, durability, or impact resistance then why doesn't Titus use them on its RX 29er, El Guapo, or Supermoto? that seems inconsistent.
    this is not proof that the carbon stays are defective in design.

    here are a few possible reasons.
    1. popular opinion: it won't matter how much better it is if people don't trust it. especially on a huck bike.
    2. law of scale: they just sell more RX and MLs, so its worth while to sink the money into developing it. Supermoto. Guapo, 29er are just small potatoes in production numbers. ( I own 2 SuMos and have never ever seen another one on a trail. ever.
    3. the ML and RX were losing ground weight wise compared the other light weight XC bikes. like 575 and ASR.
    4. the ML might have a chronic issue with chain stay life. so a redesign was in order.
    5. Guapo and 29er are in their first year. maybe it will come in later like the ML or RX
    6. Supermoto uses an old old chain stay. same as the old quasi moto. IMHO the sumo is due for a major over haul. not worth it to sink the money into it. at this point.

    see there are lots of reasons...

    I've been a hardware design engineer for 10 years in high tech industries in the silicon valley. more years then that counting MFG and QA jobs and its the same story everywhere, my boss is never short on projects. but I only work on a few at a time. so he has to pick and choose what he is going to use his resources on. they call it prioritizing. its just cost vs benefit vs risk. even things I want fixed, I don't get to work on either. unless I want to write a project proposal to get cash. people always seem to think engineering is a big endless stable of guys waiting to work on something. but its not.


    and I,m not saying that I know jack about composites.

  69. #69
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    Quote Originally Posted by Dropin%Dug
    I know when I went from the Alu stays on my RXogrid to the newer carbon triangle the bike went to another level of "quietness" in its ride. The combo of the Exo and the Carbon rear is mind blowing in its smoothness.....like liquid chamois butter!!!
    It's cool to hear first hand that a carbon upgrade is noticeable even on a FS rig! Could you compare the change in feel to perhaps running a larger casing tire?

    My impression is that many of the frequencies damped by carbon components will also be damped by a big volume DH tire. Why not put carbon seatstays on long travel bikes? It could be that you just won't notice the ride quality when you're on so much rubber...and you spend so much time off of said rubber anyway that your risk of crash damage is too high.

    Quote Originally Posted by demo_slug
    Supermoto uses an old old chain stay. same as the old quasi moto. IMHO the sumo is due for a major over haul. not worth it to sink the money into it. at this point.
    Care to speculate on what this major overhaul might entail? More travel perhaps??

  70. #70
    the 36 year old grom
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    Quote Originally Posted by Blofeld
    Care to speculate on what this major overhaul might entail? More travel perhaps??
    All I know for sure is that they didn't even bring one Sumo to the sea otter. lots of Guapos, MLs, RX, carbon Rx. not one sumo. I asked one of the guys at the tent "where are the SuMos", he said "they didn't have many (SuMos) left".

    in regards to a new SuMo, I don't see it as a "how much more travel" thing and more of a "new geometry" thing. longer wheelbase, slacker angles, low BB with bigger forks. just more DH specific. more "highline" or maybe just a straight out DH bike.

    the current SuMo is a fantastic long travel heavy duty trail bike, there are very few bikes with that much travel and such a short wheelbase and So overbuilt. it just doesn't fit into the "standard" pigeon hole.

  71. #71
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    Quote Originally Posted by blackagness
    Well where I think Demo is coming from is why in the world would "bike guy's/experts" that were giving you the tour have a clue about corrosive bonding techniques bla, bla bla. They've been doing it for a while as have several other companies why in the world would you assume any one of them doesn't know as much as you do about this stuff> After all they do feed their family and make their lively hood on this stuff. I personally have never heard of any one's cf/al bike corroding out from under them. Maybe what you saw wasn't corrosion? Maybe it was just resin erroding away under normal use or something. Either way what ever it was perhaps it's something completely normal?
    But I have heard of some CF forks with aluminum steerers failing at the mating point,isn`t this why CF forks with CF steerers are considered "stronger and more reliable"?
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  72. #72
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    Quote Originally Posted by jeffro
    If the process of using cf seatstays reduces weight with no negative side effect to stiffness, durability, or impact resistance then why doesn't Titus use them on its RX 29er, El Guapo, or Supermoto? that seems inconsistent.
    I am under the impression that just as this is the first year on the moto, they will start putting CF stuff on the other bikes in the line. Some of the shop guys at the local titus dealer seemed down on the CF bonding part and stated that they have had a couple bikes come back already because of this. Don't know if this was true or not. Not to mention that they kept pushing a medium sized titus (without even bothering to fit me!) or a Santa Cruz.

  73. #73
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    Quote Originally Posted by anand
    Some of the shop guys at the local titus dealer seemed down on the CF bonding part and stated that they have had a couple bikes come back already because of this.
    That's interesting. I'm curious how big the problem is.. assuming they are telling you the truth. I dont' know why they would tell you this if it weren't true. It seems like it would harm a sale.

  74. #74
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    Quote Originally Posted by jeffro
    That's interesting. I'm curious how big the problem is.. assuming they are telling you the truth. I dont' know why they would tell you this if it weren't true. It seems like it would harm a sale.
    Hard to say sometimes. Some of those guys were not big Titus fans and kept pushing the Santa Cruz. Drove me nuts. Want a Titus dammit!

  75. #75
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    Quote Originally Posted by Blofeld
    It's cool to hear first hand that a carbon upgrade is noticeable even on a FS rig! Could you compare the change in feel to perhaps running a larger casing tire?

    My impression is that many of the frequencies damped by carbon components will also be damped by a big volume DH tire. Why not put carbon seatstays on long travel bikes? It could be that you just won't notice the ride quality when you're on so much rubber...and you spend so much time off of said rubber anyway that your risk of crash damage is too high.
    I'm running 2.1 Spec Roll-X's now and I might be able to get a 2.3 to fit but not sure I'd want to. You're right that a larger volume tire will smooth out the ride. However, since I use the RX more for racing, my feeling is that I want to keep the rolling resistance at a minimum and the 2.3 will also impact handling.

    Bottom line is that Carbon stays do damp out vibration and have been used for some time. Look at the early GF Sugar 1's....not sure how many failures they saw, but I feel the risk is minimal.
    Last edited by Dropin%Dug; 06-21-2007 at 11:40 AM.
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  76. #76
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    Quote Originally Posted by demo_slug
    the current SuMo is a fantastic long travel heavy duty trail bike, there are very few bikes with that much travel and such a short wheelbase and So overbuilt. it just doesn't fit into the "standard" pigeon hole.
    I dunno Demo...I may piss some SuMo folks off with this statement, but I rode one for a year and finally dumped it. I had it as light as 38lbs with a Fox36/Manitou Swinger 4Way, but the thing was still a pig in my book. I do agree they are built like a brick sh!thouse but I wonder if they are maybe overbuilt for HD Trail use. FR??? Way cool!!!

    That's when I jumped to the Foes FXR and I think the 2008 Fly that Brent is working on may be a another departure point in the odyssy called FS Evolution. The Fly will come in at around 36lbs with 8" of travel. With a few tricks you might be looking at 34-35lbs with a Totem Air.

    The term "Heavy Duty Trail Bike" which is a subset of the FR designation is about to be transformed by these types of rides. Then again maybe it's the FR design being dragged to where the HD Trail bikes are now.

    No doubt there is a difference between a 6" Trail Bike and a 7-8" FR rig as far as focus (Climbing/DH Bashing as opposed to full on Stunting) The SuMo to me fit the FR realm well but Titus seemed to want to try to target it at the HD Trail realm. Maybe the new design is headed were Brent is looking, but then you begin to wonder whether they will cut the legs out from under the El Guapo.
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  77. #77
    the 36 year old grom
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    Quote Originally Posted by Dropin%Dug
    I dunno Demo....
    dunno what?? seems like you agreed with me. but I would add that the swigner 4way you had on your SuMo was 2.5 pounds of junk. Fox rear shox and spring would have shaved over 300gs off and smoothed things out a bunch. and works best set up 7x7. compared to other 7x7 bikes its not really over weight.

    but, it just seems our definition of HD is different. the FXR is not what I would call heavyduty. I don't think Foes would endorse a Fox 40 on the front of it. and they had a 200lb rider weight limit when they released it. but it is eye candy. just another neat bike I can't buy and 36lbs with 8" isn't HD either. for the record, I've only ever recomended SuMo for heavy dudes. or really strong little dudes that go way to big. it is overbuilt. never recomended it to foes%nancyboy.

  78. #78
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    Quote Originally Posted by demo_slug
    dunno what?? seems like you agreed with me. but I would add that the swigner 4way you had on your SuMo was 2.5 pounds of junk. Fox rear shox and spring would have shaved over 300gs off and smoothed things out a bunch. and works best set up 7x7. compared to other 7x7 bikes its not really over weight.

    but, it just seems our definition of HD is different. the FXR is not what I would call heavyduty. I don't think Foes would endorse a Fox 40 on the front of it. and they had a 200lb rider weight limit when they released it. but it is eye candy. just another neat bike I can't buy and 36lbs with 8" isn't HD either. for the record, I've only ever recomended SuMo for heavy dudes. or really strong little dudes that go way to big. it is overbuilt. never recomended it to foes%nancyboy.

    Wow great stuff and very insightful demo!


    You too doug! Your coming up with some gems, but I'm going with demo regarding the SuMo. I think he discribes it to a T except that I thought the "new SuMo" had even more of a FR bent and was drifting away from the FR/Trail thing with slacker angles and such? Though I think it might be lighter? Anyway I've never even seen the new one in persone so I don't know.

  79. #79
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    Quote Originally Posted by demo_slug
    I've only ever recomended SuMo for heavy dudes. or really strong little dudes that go way to big. it is overbuilt. never recomended it to foes%nancyboy.
    Yup... I'm witness of it... There's a thread a while ago when I was showing interest on a SuMo and Demo said "no".

    I'm a bit stubborn still and I may consider a '04 "XC" SuMo with the 5.7" link...
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  80. #80
    the 36 year old grom
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    Quote Originally Posted by Warp
    I'm a bit stubborn still and I may consider a '04 "XC" SuMo with the 5.7" link...
    get some saint cranks too. they only add half a pound. and some mavic 729s. 36 spoke. and you got to run full DH tubes too.

  81. #81
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    Quote Originally Posted by demo_slug
    dunno what?? seems like you agreed with me. but I would add that the swigner 4way you had on your SuMo was 2.5 pounds of junk. Fox rear shox and spring would have shaved over 300gs off and smoothed things out a bunch. and works best set up 7x7. compared to other 7x7 bikes its not really over weight.

    but, it just seems our definition of HD is different. the FXR is not what I would call heavyduty. I don't think Foes would endorse a Fox 40 on the front of it. and they had a 200lb rider weight limit when they released it. but it is eye candy. just another neat bike I can't buy and 36lbs with 8" isn't HD either. for the record, I've only ever recomended SuMo for heavy dudes. or really strong little dudes that go way to big. it is overbuilt. never recomended it to foes%nancyboy.
    I'm in a perpetual state of "dunno", but that's the nature of technological revolution...

    At the time I had my SuMo the DHX Air was a pipedream. The Swinger 4-way was the only air option and recommended as a replacement to the DHX Coil by Titus. But you're right, it's a strange cusp right now, kinda like where 5" trail bikes were 5 years ago relative to 4" bikes. Now 6" is the norm based on the advances in suspension.

    Demo....I'm gonna start this as a new thread cause I really do think it's a good subject for conversation.
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