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  1. #1
    Senior Member adamlaw's Avatar
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    Bike accident/front wheel failure - how did it happen?

    I took my son (14 years) for his first ride of the season. I checked his 2003 Merlin
    Agilis beforehand - checked the tires, the brakes and lubricated the chain. We were cycling on
    the flat about 1 mile from our house when I heard a noise behind me
    and saw him down on the ground. He sustained injuries to his face,
    legs and hands. He was mildly concussed. His helmet saved his head.
    He broke 3 teeth and damaged his lips. A CT scan showed nothing else
    was damaged. He was courageous throughout.

    I have attached a few images I took with my cell-phone camera (I
    didn't have time to charge my camera up this evening). One spoke was
    broken. Another bent. Both blades of the carbon fiber fork (has a
    Merlin logo on it) were broken/fractured. I don't know if todays accident was caused
    by a mechanical failure of a spoke, or if somehow the front wheel came
    out of the front fork - tho' he was riding on the flat and I think I remember
    tightening the front wheel release. I haven't seen enough bikes after
    similar accidents to be able to reconstruct what caused this accident.
    I note the rim looks fine. However, I am alarmed at the way the
    carbon forks just fractured. I wonder if they were steel if this
    would have made much difference - he would have been thrown anyhow.
    But it makes me less certain about the wisdom of carbon forks. It
    may be that this was a hard impact that would have crumpled a steel
    fork.
    The wheels on his bike have Oxus rims (I have never heard of them) and bladed black spokes,
    with a hub I can't identify. I note he had a spoke failure on the back wheel at the end of the season and we were advised by our trusted bicycle mechanic to just replace the spoke and not the wheels.
    My son was rated the first triathlete in the 14 years and under class in 2006 and is keen to ride again. My wife is less keen. Any advice about replacements for the fractured fork and broken wheels? I am looking for a combination that is less likely to fail.
    Attached Images Attached Images

  2. #2
    Ono! sestivers's Avatar
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    Apparently, his concussion caused him to forget that he was hit by a bus while you weren't looking.

    There must be more details, your post makes it sound like a "just riding along" (JRA) incident.

    It's possible that something wedged in his front wheel and was then carried to the fork. The distance from the center of the hub to the broken spoke area looks about the same as the distance from the center of the dropout to the broken fork area. How fast were you going?
    Steve

  3. #3
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    Youch! Sorry to hear about his injuries I'm glad nothing was permanently damaged, except for the bike.

    Does he remember the accident? Some sequence of events leading up to it? A fork shouldn't just fall apart unless its been subjected to some trauma, and a spoke breaking spontaneously is not enough to count. Is it possible the fork had been damaged beforehand? Even just whacked into a doorframe by accident? How closely did you inspect the fork itself before you guys left?

    [edit] sestivers' suggestion makes a lot of sense. If something solid was stuck through the front wheel, it would have impacted on the spokes and the fork, which not coincidentally were the two things that broke. Were there branches in the area? Something that could have fallen across his path? Did he have a pump on his frame, which might have detached and fallen into the wheel?

  4. #4
    Last one to the top... Little Darwin's Avatar
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    I would concur that it looks like something got caught in the spokes...

    I suspect that if the forks had been steel they would be bent and the result on your son's body would have been the same.

    Of course, this is based on les information than even you have.

    My best wishes for your sons quick healing.
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    - Ralph Waldo Emerson

  5. #5
    Senior Member Deanster04's Avatar
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    I would try and locate the local distributor of the fork and wheel and discuss this with them. Have your first discussion with a very experienced local mechanic who doesn't have a vested interest in the outcome. My first thought was that the wheel came out of the dropouts. Recently in a time trial in a pro race a rider was riding along in the TT and hit a bump at high speed. This front wheel popped out with disasterous results. Can't remember the rider's name but he did go to the hospital. I can't see any results of a crash on the dropouts where they may have dug into the ground. One of the problems with the wheels with unusual spoke patterns is that when you break a spoke the wheel will go severly out of round and no longer fit the tight tolerances of the front fork and can cause the bike to stop abruptly. What is supremely wierd is the breakage of the fork where it fractured. Was the bike new or used when you bought it? How old was the fork? Who made it? All these questions are germain to solving this problem. Never buy a used carbon fork if you are planning on racing or like high speed riding. Don't go cheap on radially spoked wheels, start your son out on some good quality standard 3X laced wheels. In some cases they are lighter than a lot of botique wheels and far safer. A steel fork would have bent not broken like the Carbon fork. If they were used and had been in an accident before you wouldn't have seen the damage whereas a steel fork bends and can be safely cold set back into position. Hopefully the frame was OK. You may never really know what the cause was. Good luck.

  6. #6
    Senior Member Bill Kapaun's Avatar
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    I'm kind of wondering if the fork broke and the spoke damage was caused by that. I guess we can all come up with different scenarios and one of them might even be correct.

  7. #7
    Non Tribuo Anus Rodentum and off to the next adventure (RIP) Stacey's Avatar
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    Sorry to hear of your sin's misfortune. Thankfully his injuries weren't more severe!

    Question: After the crash, were the fork blades still afixed to the hub via the Q/R skewer or had they seperated?

  8. #8
    Senior Member robo's Avatar
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    I was thinking the same thing as Deanster04 - if the QR was loose and the wheel popped out, the spoke could easily have been broken in the ensuing mess, especially if one of the fork legs when 'through' the spokes.

    However, it's hard to see if there is damage to the dropouts, which would have happened presumably if the fork legs snapped when they hit the ground, which seems the most likely scenario for such catastrophic failure of BOTH fork legs at the same time (to me, anyway)..

    It seems surprising that something could have wedged in the spokes and smashed through two sturdy carbon fiber legs, while only breaking one spoke, which is the other scenario.


    I hope your son makes a full recovery anyway...

  9. #9
    Senior Member robo's Avatar
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    Actually, i just realized that the answer is pretty clear.. if the lower fork legs were still clamped to the hub by the QR after the accident, it must have been something stuck in the wheel or some sort of insane random failure. However, if the lower fork legs were separated from the hub...

    ... then most likely the QR wasn't tightened.

    A properly tightened QR should make an extremely solid connection, and unless the wheel was somehow pulled directly downwards with incredible force, the vertical dropouts ensure that the wheel stays in the dropouts no matter what.. unless the QR was loose.

  10. #10
    Senior Member adamlaw's Avatar
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    Quote Originally Posted by sestivers
    Apparently, his concussion caused him to forget that he was hit by a bus while you weren't looking.

    There must be more details, your post makes it sound like a "just riding along" (JRA) incident.

    It's possible that something wedged in his front wheel and was then carried to the fork. The distance from the center of the hub to the broken spoke area looks about the same as the distance from the center of the dropout to the broken fork area. How fast were you going?
    We were going about 10 - 12 mph. A driver witnessed the accident, but wasn't able to provide much in the way of extra details. I couldn't find anything on the road that may have caused this.

  11. #11
    Senior Member adamlaw's Avatar
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    Quote Originally Posted by GRedner
    Youch! Sorry to hear about his injuries I'm glad nothing was permanently damaged, except for the bike.

    Does he remember the accident? Some sequence of events leading up to it? A fork shouldn't just fall apart unless its been subjected to some trauma, and a spoke breaking spontaneously is not enough to count. Is it possible the fork had been damaged beforehand? Even just whacked into a doorframe by accident? How closely did you inspect the fork itself before you guys left?

    [edit] sestivers' suggestion makes a lot of sense. If something solid was stuck through the front wheel, it would have impacted on the spokes and the fork, which not coincidentally were the two things that broke. Were there branches in the area? Something that could have fallen across his path? Did he have a pump on his frame, which might have detached and fallen into the wheel?
    Thanks for your comments. No pump on the frame. No branches in that section of road. It was clear. I didn't see anything wrong with the fork prior to departure - however, I didn't do a high resolution inspection. I checked the front brakes for alignment and did release the front wheel and re tighten as it wasn't dead center. We cleaned off some mud on the rim just after we set off as it was catching on the brake, but the wheel spun round fine after we cleared it off. It seemed to be working fine.

  12. #12
    Senior Member adamlaw's Avatar
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    Quote Originally Posted by Deanster04
    I would try and locate the local distributor of the fork and wheel and discuss this with them. Have your first discussion with a very experienced local mechanic who doesn't have a vested interest in the outcome. My first thought was that the wheel came out of the dropouts. Recently in a time trial in a pro race a rider was riding along in the TT and hit a bump at high speed. This front wheel popped out with disasterous results. Can't remember the rider's name but he did go to the hospital. I can't see any results of a crash on the dropouts where they may have dug into the ground. One of the problems with the wheels with unusual spoke patterns is that when you break a spoke the wheel will go severly out of round and no longer fit the tight tolerances of the front fork and can cause the bike to stop abruptly. What is supremely wierd is the breakage of the fork where it fractured. Was the bike new or used when you bought it? How old was the fork? Who made it? All these questions are germain to solving this problem. Never buy a used carbon fork if you are planning on racing or like high speed riding. Don't go cheap on radially spoked wheels, start your son out on some good quality standard 3X laced wheels. In some cases they are lighter than a lot of botique wheels and far safer. A steel fork would have bent not broken like the Carbon fork. If they were used and had been in an accident before you wouldn't have seen the damage whereas a steel fork bends and can be safely cold set back into position. Hopefully the frame was OK. You may never really know what the cause was. Good luck.
    I have been thinking hard to remember how tightly I readjusted the front release prior to the ride as I too wonder if the fork came out of the dropouts. However, I don't understand how this would have happened on a level road without any bumps at a relatively slow speed. I think this is the main likelihood. This was a used bike I bought on e-bay. The former owner was a endurance cyclist and did centuries and double centuries. He appeared honest and open - specifically denied any damage. A highly experienced and competent local mechanic inspected the bike before my son ever used it and thought it was in excellent condition. Carbon fork failure seem a little far-fetched to me as human error (my own) seems statistically more likely.

  13. #13
    Senior Member adamlaw's Avatar
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    Quote Originally Posted by Bill Kapaun
    I'm kind of wondering if the fork broke and the spoke damage was caused by that. I guess we can all come up with different scenarios and one of them might even be correct.
    As I mentioned above - this seemed unlikely to me. However, as you say there are many ways this could have happened even with the evidence at hand.

  14. #14
    Senior Member adamlaw's Avatar
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    Quote Originally Posted by Stacey
    Sorry to hear of your sin's misfortune. Thankfully his injuries weren't more severe!

    Question: After the crash, were the fork blades still afixed to the hub via the Q/R skewer or had they seperated?
    They were separated - making wonder if this was the primary event. Tho' again why on a flat road without major bumps at a relatively slow speed.

  15. #15
    Young and unconcerned Treefox's Avatar
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    Were the ends of forks still attached to the wheel?

    If not, maybe: the wheel came off, the top of the fork bashed into the top of the wheel, breaking and bending spokes and the dropouts hit the ground, snapping off the ends of the fork?
    Die schokoladenseite des radfahrens.

  16. #16
    Young and unconcerned Treefox's Avatar
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    Quote Originally Posted by adamlaw
    They were separated - making wonder if this was the primary event. Tho' again why on a flat road without major bumps at a relatively slow speed.
    He could've been sort of bouncing around a bit - or just stood up to shift his weight and took weight off the un-fastened front wheel.

    If the quick release were fastened, I would've expected the two ends of the fork blades to be hanging from the wheel still.
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  17. #17
    Senior Member robo's Avatar
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    I guess he could have pulled up on the handlebars for some reason..

  18. #18
    Senior Member adamlaw's Avatar
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    Quote Originally Posted by robo
    Actually, i just realized that the answer is pretty clear.. if the lower fork legs were still clamped to the hub by the QR after the accident, it must have been something stuck in the wheel or some sort of insane random failure. However, if the lower fork legs were separated from the hub...

    ... then most likely the QR wasn't tightened.

    A properly tightened QR should make an extremely solid connection, and unless the wheel was somehow pulled directly downwards with incredible force, the vertical dropouts ensure that the wheel stays in the dropouts no matter what.. unless the QR was loose.

    I think you are likely correct. However, I remain puzzled why this occurred on a flat road. I suppose the wheel had to come off somewhere in this circumstance. As I stated above, I thought I had tightened the release - but memory can play tricks. I did lift up the bike and spin the front wheel about 100 yards from our house as my son said he could hear friction. It was some mud on the rim, which I removed. At that time the front wheel spun round several turns and didn't drop, as I would expect if the release was not tightened. However, it may still have been a partial tightening and then sprung open for some reason in the next few hundred yards. There is a relatively steep, bumpy foot path we went down connecting the end of our street with the next main road that is parallel to our own. It may have come loose on that. I will have the local mechanic look at it.

  19. #19
    Senior Member adamlaw's Avatar
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    Quote Originally Posted by Treefox
    He could've been sort of bouncing around a bit - or just stood up to shift his weight and took weight off the un-fastened front wheel.

    If the quick release were fastened, I would've expected the two ends of the fork blades to be hanging from the wheel still.

    This seems the most likely explanation to me, too.

  20. #20
    Ono! sestivers's Avatar
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    Quote Originally Posted by adamlaw
    There is a relatively steep, bumpy foot path we went down connecting the end of our street with the next main road that is parallel to our own. It may have come loose on that.
    With all of the new information, I am now convinced that the front wheel fell off. What type of quick release (QR) do you have on the front wheel? It does not appear that the fork had the safety tabs (aka lawyer lips) installed on it, so you should be using enclosed (not exposed) cam QRs. If you weren't, this would have contributed to the wheel coming off. See this Sheldon Brown article to see what I'm talking about.

    So my theory now goes as follows:
    Front wheel QR is insufficiently tightened (even though it seemed to be tight enough) at home.
    Bumpy road loosens the QR.
    No safety tabs are in place to hold the wheel on with the loose QR.
    Wheel comes out.
    Fork is forcefully smashed into the pavement. On its way down, it goes through some spokes on the front wheel.
    Fork breaks.
    Steve

  21. #21
    Senior Member DannoXYZ's Avatar
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    Sorry to hear about your son's injuries.

    I've been numerous crashes in races @ 30-40mph. One was at the Creston Road Race in SLO. Going down a straightaway, someone tangled up front and my teammate got hit on his handlebars from the side. Instantly turned his handlebars 90-degrees @ 40mph. Fork and wheel shattered instantly and he went over and had same injuries as your son, broken face and concussion. After we gathered up the pieces, we saw that one steel fork-blade had snapped off at the crown, the other was bent 90-degrees sideways. The rim had shattered into 5 pieces. Lots of bent and a couple broken spokes. But the hub was still firmly holding onto both fork-blades.

    On your son's bike, if the fork-ends that broke off the fork weren't attached to the wheel, I'd have to conclude that the QR wasn't fully tightened. He may have hit a bump and gotten a little bit of air, or rode over a hole and the wheel dropped down. Once the front wheel came out, the fork hit the ground and broke. The spokes broke when they got caught up in the snapping fork.
    Last edited by DannoXYZ; 03-27-07 at 10:31 AM.

  22. #22
    Senior Member
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    Couldn't see it in the picture, but is the QR still attached to the wheel?

  23. #23
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    More pictures and from different angles.
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  24. #24
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    by any chance is the QR one of those skewers that Shimano recalled a while back?

  25. #25
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    Quote Originally Posted by adamlaw
    They were separated - making wonder if this was the primary event. Tho' again why on a flat road without major bumps at a relatively slow speed.
    Sorry to hear about your son's crash.

    I think Stacey's question and the OP's answer pretty much sum it up. The wheel came out of the dropout. If the forks had snapped on their own (highly unlikely), the hub would have still been connected to the dropouts.

    Sounds like this is what happened: The wheel comes out of the fork dropouts, one of the fork blades goes into the wheel and broke spokes, the fork ends hit the pavement and the forks snap.
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