Advertise on Bikeforums.net



User Tag List

Page 1 of 2 12 LastLast
Results 1 to 25 of 37
  1. #1
    Senior Member loimpact's Avatar
    Join Date
    Dec 2013
    Location
    SoCal
    My Bikes
    2014 Cannondale Supersix Evo 3; 2014 Cannondale Quick 4; 2014 Cannondale Crash 4 hi-mod
    Posts
    420
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Carbon fork use after a fall......

    Question #1 .) So after a fall what would keep you from riding on said carbon forks, assuming no damage can be found on the forks themselves?? (Approximate 10mph fall, though hard to say w/ screeching brakes & landing on the side) I've read opinions on both sides of the carbon-fork safety fence.

    Question #2 .) If replacement is the only option, what needs to be considered shopping an aftermarket carbon fork for replacement on the frame. (I'm also looking into oem but aftermarket appears to look cheaper unless I'm mistaken & wouldn't compromise fit if it's too hard to match up)

    Bike is a Cannondale Quick 4 (Aluminum frame, carbon forks w/ 1-1/8" non-tapered steerer, head tube is 20cm / 7.9" if it helps)

    TIA

  2. #2
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    25,415
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Do a very careful inspection of the fork looking for deep scratches or any signs of cracks or damaged areas. Flex the legs at the crown and the steerer and see if there is any unusual looseness or relative motion. If it passes you should be ok.

  3. #3
    Senior Member
    Join Date
    Jan 2013
    Location
    High Plains
    My Bikes
    old clunker
    Posts
    763
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)
    How far did the fork fall?

  4. #4
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    25,415
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by AnkleWork View Post
    How far did the fork fall?
    Apparently far enough to hit the ground.

  5. #5
    Senior Member
    Join Date
    Nov 2010
    Location
    River City, OR
    Posts
    569
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Carbon forks are "tougher" than we might give them credit for. I have however seen catastrophic failures with carbon forks, but they were a result of some heavy duty impacts (car crashes etc.) that no fork would have survived. The difference is that the carbon forks shattered, whereas steel forks would have twisted so as to be un-rideable.

    Not all carbon forks are built the same, even those with a carbon steerer. If yours have as alloy steerer, the crown is most likely alloy as well with carbon legs bonded at some point. This is where you want to look for any compromise at the joint. If I see anything that appears to be a separation at a joint I use nail polish to fill the area and take a ride around the block. If the nail polish cracks, bingo- loose joint.

    Other than that- I go with HillRider' suggestions.

  6. #6
    Senior Member loimpact's Avatar
    Join Date
    Dec 2013
    Location
    SoCal
    My Bikes
    2014 Cannondale Supersix Evo 3; 2014 Cannondale Quick 4; 2014 Cannondale Crash 4 hi-mod
    Posts
    420
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    image.jpgInteresting with the nail polish bit. Definitely not far fall, just down to the ground. On its side. Not knowing exactly where the transition would be, I'm going to post a hack-job pic from my iPad but just to illustrate where the fork shows the obvious CF ribbons but then transitions where it's solid black. (I'm not assuming it's not CF there, but it's definitely not showing like on the lower fork). I assume the steerer is alloy.

    And to HillRider.....You mean remove the front wheel & actually pry the forks outward/inward to look for movement? (I haven't pulled the fork & would rather not unless you think it's vital).

    Thanks again! Great advice so far!




    Quote Originally Posted by reddog3 View Post
    Carbon forks are "tougher" than we might give them credit for. I have however seen catastrophic failures with carbon forks, but they were a result of some heavy duty impacts (car crashes etc.) that no fork would have survived. The difference is that the carbon forks shattered, whereas steel forks would have twisted so as to be un-rideable.

    Not all carbon forks are built the same, even those with a carbon steerer. If yours have as alloy steerer, the crown is most likely alloy as well with carbon legs bonded at some point. This is where you want to look for any compromise at the joint. If I see anything that appears to be a separation at a joint I use nail polish to fill the area and take a ride around the block. If the nail polish cracks, bingo- loose joint.

    Other than that- I go with HillRider' suggestions.
    Last edited by loimpact; 01-05-14 at 09:03 PM.

  7. #7
    Senior Member
    Join Date
    Apr 2009
    Location
    New Rochelle, NY
    My Bikes
    too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
    Posts
    20,499
    Mentioned
    44 Post(s)
    Tagged
    1 Thread(s)
    Realistically, there's no way to know for sure if the fork is safe, certainly not at the remove via the Internet.

    You have to look for signs and make your own assessment.

    OTOH- the integrity of the fork may not mean anything. What matters is what you think it's integrity is. At some time, you'll be riding down some hill at 35mph or more, maybe of rough pavement, and do you want to be worrying about the fork

    Either convince yourself that it's 100% OK or replace it so you can have peace of mind.
    FB
    Chain-L site

    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  8. #8
    Senior Member loimpact's Avatar
    Join Date
    Dec 2013
    Location
    SoCal
    My Bikes
    2014 Cannondale Supersix Evo 3; 2014 Cannondale Quick 4; 2014 Cannondale Crash 4 hi-mod
    Posts
    420
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Understood. Just trying to find the best way to go about making that assessment.

    The fork *appears* to be in good shape. No disruption to the surface of the fork that I can see at all. I don't know if the handlebars twisted & the grips & tire took the brunt but there literally appears to be no markings at all, however, the bike shop's assessment gave me 2 points of view.

    View 1 ----- The mechanic that worked on it said he wouldn't hesitate to ride it.

    View 2 ----- The manager of the shop suggested it not be ridden. Once a bike's gone down w/ a carbon fork, they simply consider it a bad fork. (And thus I've come across many a thread here about such debates)

    Still awaiting word back on specifics of flexing the fork to determine how to assess possible shortcomings!

    Thanks again!

    Quote Originally Posted by FBinNY View Post
    Realistically, there's no way to know for sure if the fork is safe, certainly not at the remove via the Internet.

    You have to look for signs and make your own assessment.

    OTOH- the integrity of the fork may not mean anything. What matters is what you think it's integrity is. At some time, you'll be riding down some hill at 35mph or more, maybe of rough pavement, and do you want to be worrying about the fork

    Either convince yourself that it's 100% OK or replace it so you can have peace of mind.

  9. #9
    Senior Member
    Join Date
    Dec 2010
    Location
    Above ground, Walnut Creek, Ca
    My Bikes
    7 single speed road
    Posts
    3,854
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    i'd probably take a quick look at the fork after the fall, then, if it looked okay, i would forget about it.

    as a matter of fact, now that i think about it, i took a nasty fall a few months ago that left me with a permanently dislocated sternoclavicular joint. the aluminum framed bike had a carbon fork on it. i didn't even look at it for damage. i just limped home and never even inspected the fork. i've ridden it several hunderd miles since, so i guess it's okay.

  10. #10
    bike whisperer Kimmo's Avatar
    Join Date
    Dec 2009
    Location
    Melbourne, Oz
    My Bikes
    copy/paste links: http://velospace.org/node/36949 http://velospace.org/node/47746 http://velospace.org/node/47747
    Posts
    6,828
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by loimpact View Post
    No disruption to the surface of the fork that I can see at all.
    This confirms no impact damage, which is all you should be concerned about. In the absence of impact damage, the only indirect forces (through the wheel, frame and bars) that would make a difference would have to be so huge as to leave the fork obviously destroyed, likely along with much of the rest of the bike.

    Carbon forks are usually stronger than aluminium or even steel ones, except for impact resistance and clamping requirements. Most carbon forks weigh 4-500g or more, but they can be built as light as 270g.

  11. #11
    Senior Member rekmeyata's Avatar
    Join Date
    Sep 2010
    Posts
    5,721
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    A CF fork is fragile but the blades were supported by the front axle so I doubt any damage occurred...however it is always wise to have a fork or frame inspected by a professional to be safe. Keep in mind too that just because there's no outside damage apparent doesn't mean that inside the fork doesn't have damage. A lot of damage is hidden from view because the damage went to the inside. Again have a pro inspect it.

  12. #12
    Senior Member Looigi's Avatar
    Join Date
    Dec 2010
    Posts
    7,142
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    I've broken more calcium frames than carbon ones.

  13. #13
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My Bikes
    '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
    Posts
    25,415
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by loimpact View Post
    And to HillRider.....You mean remove the front wheel & actually pry the forks outward/inward to look for movement? (I haven't pulled the fork & would rather not unless you think it's vital).
    That's exactly what I mean. Certainly and at a minimum remove the front wheel and see if the fork legs wiggle or move independently. Much better would be to remove the fork completely from the bike as that's the only way to adequately inspect the steerer/crown interface.

    The bike shop's assessment is expected. The mechanic would have to pay for his own replacement fork. The owner wants YOU to pay him for a replacement fork.

    i took a nasty fall a few months ago that left me with a permanently dislocated sternoclavicular joint. the aluminum framed bike had a carbon fork on it. i didn't even look at it for damage. i just limped home and never even inspected the fork. i've ridden it several hunderd miles since, so i guess it's okay.
    Interesting. I had a similar accident last July that left me with a mild concussion and a similar A/C joint separation but the bike (Ti frame, all-carbon fork) was pretty much untouched. However, after I got home from the hospital I gave the entire bike a very thorough inspection with great emphasis on the fork. Again I found no damage and have ridden the bike ever since.

  14. #14
    Senior Member
    Join Date
    Nov 2005
    Posts
    1,414
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    If you did not break any carbon threads, I would take a nickel and tap the suspected area and then a known good corresponding area (opposite fork blade). If they sound the same I would ride it.

  15. #15
    Senior Member rekmeyata's Avatar
    Join Date
    Sep 2010
    Posts
    5,721
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    I think a bike made of bone would be pretty heavy, but it might look cool!

  16. #16
    Senior Member loimpact's Avatar
    Join Date
    Dec 2013
    Location
    SoCal
    My Bikes
    2014 Cannondale Supersix Evo 3; 2014 Cannondale Quick 4; 2014 Cannondale Crash 4 hi-mod
    Posts
    420
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Fred Smedley View Post
    If you did not break any carbon threads, I would take a nickel and tap the suspected area and then a known good corresponding area (opposite fork blade). If they sound the same I would ride it.
    Funny you say that, I literally JUST got back from another bike shop to get their opinion on the matter and the suggestion given to me was "the quarter test" and he said the same thing.

    The other guy suggested that I visibly examine it and that if there are no crack lines visible it's probably fine.

    The last advice given was that he had never seen a catastrophic failure of a carbon fork. Even on a carbon frame, he suggested that it will make noises that cannot go away & eventually there will be a visible sign to confirm the crack. (And on a full carbon crash/fall they'll do the quarter test as well to save a guy thousands if they can).

    I can't speak from personal experience so I don't know that to be true or not, but I think catastrophic failure is my biggest concern anyway so that sounded like good news unless it's false, then of course it's not.

  17. #17
    Senior Member rekmeyata's Avatar
    Join Date
    Sep 2010
    Posts
    5,721
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    did they tell you what you should be listening for? by lightly tapping the CF fork or frame the noise will be sort of a clack type of sound whereas a damaged part will have more of a dull thud type of noise. However there is no real way to tell if a fork or frame is damaged by doing this if the damage is subtle, the only real way is with impulse thermography, something no bike shop can do and I doubt many manufactures can do either.

    See this for more detail: http://www.carbon-bike-check.com/html/forces.html

  18. #18
    Senior Member loimpact's Avatar
    Join Date
    Dec 2013
    Location
    SoCal
    My Bikes
    2014 Cannondale Supersix Evo 3; 2014 Cannondale Quick 4; 2014 Cannondale Crash 4 hi-mod
    Posts
    420
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Thanks for the audible description. It's kind of what they said too. It sounds like they do it quite a bit as I'm sure folks who dump big money on a full carbon frame would rather not dump the whole bike & hope on their last dollar they could salvage a CF *anything*, especially a full-frame!!!

    I'll be doing the test here shortly with both a nickel and a quarter just for good measure.

    I'll also give the forks a good tug to test for uniform resistance just for giggles. I had the bike at work today but literally couldn't get a peaceful minute to play with it outside of taking it to that bike shop on my lunch.

    Will post back here shortly. (I'll try & get some good pics too, if it matters)

    In the meantime.....something impressive to watch....(at least *I* was impressed) -------->

    http://www.youtube.com/watch?v=lrjId0-K-Ts
    Last edited by loimpact; 01-06-14 at 07:45 PM.

  19. #19
    Senior Member Wilfred Laurier's Avatar
    Join Date
    Feb 2013
    Posts
    1,449
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    if you have no evidence indicating a direct blow to the fork
    such as deep scratch or other mark where the fork impacted something

    and the crash did not involve a front end impact like slamming into the back of a parked car
    then the fork is almost definitely fine

    as for what the shop mechanic and his boss told you
    the boss not only benefits directly from the sale of a new fork
    but probably also fears liability if he tells you it is safe to ride and he is wrong
    while the mechanic doesnt worry as much about lawsuits and lawer fees

  20. #20
    bike whisperer Kimmo's Avatar
    Join Date
    Dec 2009
    Location
    Melbourne, Oz
    My Bikes
    copy/paste links: http://velospace.org/node/36949 http://velospace.org/node/47746 http://velospace.org/node/47747
    Posts
    6,828
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    +1 you'll get a more honest answer from the mechanic than the manager.

  21. #21
    Senior Member loimpact's Avatar
    Join Date
    Dec 2013
    Location
    SoCal
    My Bikes
    2014 Cannondale Supersix Evo 3; 2014 Cannondale Quick 4; 2014 Cannondale Crash 4 hi-mod
    Posts
    420
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Well, I literally checked these forks over fraction of an inch by fraction of an inch. There is literally no surface damage whatsoever. Tap test is uniform (side for side) throughout on similar sides inside, outside, upside-down. I also tried to pry the forks together, apart, etc. and they are tight as a drum with zero noises coming from anywhere. Without a vise, I literally tried to get movement out of the steering tube but there is none. This sucker's as tight as I can tell from an unfallen one.

    As for the fall, it did involve smacking into a car but (aside from the flash of "oh s@#@!) going through my head, I cannot tell that anything except the rear of the bike.......(right-rear seat stay shows a dent ((aluminum)) on its side which only appeared to compromise brake adjustment)........the front shows no evidence of contact with anything. Front wheel is true. Even skewer ends are clean. Handlebars had about 1/2" of tweak but bars, stem, tube, forks, etc. all appear true as can be with no evidence of contact.

    I deduce (or induce?) that this sucker's certainly as road worthy as *my* skills can tell. It'll take backup duties, for sure, but I think it better than the "parts bike" I feared.

  22. #22
    bike whisperer Kimmo's Avatar
    Join Date
    Dec 2009
    Location
    Melbourne, Oz
    My Bikes
    copy/paste links: http://velospace.org/node/36949 http://velospace.org/node/47746 http://velospace.org/node/47747
    Posts
    6,828
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    Your fork is fine; I'd be more worried about the frame.

    Aluminium can be almost as bad as carbon when it comes to dings, depending on how highly it's engineered.

  23. #23
    Senior Member rekmeyata's Avatar
    Join Date
    Sep 2010
    Posts
    5,721
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    I too think the fork is fine, like I said the fork is supported substantially by the hub which keeps the blades from moving, if you remove the hub and laid the fork on it's side and stumped one blade with your foot it would snap like a toothpick, but the hub prevents that. The only real issue with impact is the steerer tube but it's round and substantially thick and would be very difficult to break. Now there has been incidences of forks failing, but almost all of those have been cheap lightweight Asian made forks.

    I too would be more concerned about the dent on the stay, aluminium does not take well to dents or bending, whether or not your particular dent is a problem...probably since you had to readjust the brake, and keep in mind the right rear stay takes more torque than the left side when riding. Keep riding the bike, if the brake continues to go out of adjustment as time goes by then you will have to replace the frame or risk complete failure.

    If the other party was at fault and you got their insurance information or license plate then I would contact their insurance company and get the bike replaced, any LBS should be able to help you deal with the insurance. If for some reason you can't do any of that a new aluminum frame minus a fork shouldn't cost more than $500, then simply transfer all your components over. Heck Bikes Direct has a titanium frame and fork for just $999 including shipping.

  24. #24
    bike whisperer Kimmo's Avatar
    Join Date
    Dec 2009
    Location
    Melbourne, Oz
    My Bikes
    copy/paste links: http://velospace.org/node/36949 http://velospace.org/node/47746 http://velospace.org/node/47747
    Posts
    6,828
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by rekmeyata View Post
    ...a new aluminum frame minus a fork shouldn't cost more than $500 ... Heck Bikes Direct has a titanium frame and fork for just $999 including shipping.
    No-name carbon framesets can be had for less than half that, and you can get a whole aluminium bike, with STI, for $360!

    $500 would get you a pretty damn sweet ally frame these days.

  25. #25
    Senior Member loimpact's Avatar
    Join Date
    Dec 2013
    Location
    SoCal
    My Bikes
    2014 Cannondale Supersix Evo 3; 2014 Cannondale Quick 4; 2014 Cannondale Crash 4 hi-mod
    Posts
    420
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Actually, the whole bike was $600 which is why I just went with a new one. I'm actually working with American Express as I buy ALL higher ticket items with it. They have an unparalleled purchase protection program which I didn't even believe was true until it worked with a laptop I had purchased a couple years ago. It's an insurance policy that's part of Amex's contract with card members. Others do it now too, but I think Amex pioneered it.

    Worst case scenario, I know I've got a great parts bike. But, again, I think it's safe to say I can use it for backup duty even. I might even leave it at work for short stints at lunch or something. I'll definitely keep an eye on that rear stay tho, just in case.

    In another worst case scenario, I could even pick up a cheaper version of my bike (all alum frames til you get to the top of the line) and swap components that way too. Sounds like the real money is in the carbon forks.

    While we're at it..........Any suggestions (ebay?) for buying frames/forks or other bigger ticket stuff??
    Last edited by loimpact; 01-07-14 at 07:24 AM.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •