Crank crack

Discussion in 'Cycling Equipment' started by Ed Swierk, May 19, 2003.

Thread Status:
Not open for further replies.
  1. Ed Swierk

    Ed Swierk Guest

    Tags:


  2. "Ed Swierk" <[email protected]> wrote in message
    news:p[email protected]...
    > A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    > then, but is this something I should worry about?
    >
    > See http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-1.jpg and
    > http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-2.jpg .
    >
    > Advice appreciated.
    >
    > --Ed
    >
    > --
    > Ed Swierk [email protected]

    That is not a piece of equipment I'd like to have on my bike. Can you imagine the crankarm coming
    off under little power, your foot striking the ground and maybe getting caught in your rear
    wheel. Ouch!
     
  3. In article <[email protected]>, Ed Swierk
    <[email protected]> wrote:
    >A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    >then, but is this something I should worry about?
    >
    >See http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-1.jpg and
    >http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-2.jpg .
    >
    >Advice appreciated.

    I would replace it. It's a left arm, not particularly expensive, possible dangerous failure, oral
    surgery, etc.

    --Paul
     
  4. DiabloScott

    DiabloScott New Member

    Joined:
    May 15, 2003
    Messages:
    2,284
    Likes Received:
    1
    In my twenty years of serious riding, I've broken three cranks on the ring side, one left crankarm, and two pedals. On two of those six occasions I didn't hit the pavement hard enough to cause painful breathing for at least three weeks. Aluminum tends to fail very quickly once a crack forms and it'll always break when you're doing a hard effort like sprinting, climbing, or accelerating from a stop - which means you'll go down HARD when it happens. If this were my crank I would thank my lucky star that I saw the crack before I cracked my head, and I wouldn't ride that bike until I got a new one on there.
     
  5. Anonymous

    Anonymous Guest

    >A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    >then, but is this something I should worry about?

    Replace it ASAP. The force on a crankarm is enormous, it's just a matter of time. If you're out of
    the saddle when it breaks, you'll go face first to the bar, possibly over, possibly to the ground.
    Simply an unacceptable risk. The result would be no different than a rear pawl failure, which is one
    of the nightmares on a bike.

    Doug
     
  6. Hey, even if you don't fall or have a horrendous end of ride, if you have a crank fail halfway
    'round a 30 mile personal ride in rural America or where ever or more, you'll be hurtin' all the
    same... ruined cleats, holes in socks, blisters on feet, sun burn, or you'll be riding side saddle
    hoofing it on one leg (did that on a harley to a gas station...geez for a half of a mile or better)
    and that will ruin your day.

    not to sway you :)

    NS> not the good rider
     
  7. On Mon, 19 May 2003 15:11:21 +0000, Ed Swierk wrote:

    > A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    > then, but is this something I should worry about?
    >
    > See http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-1.jpg and
    > http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-2.jpg .
    >

    Don't worry. Replace the crank immediately instead. Imagine when it develops another crack, and
    falls off on the downstroke while climbing. Hello, top tube.

    --

    David L. Johnson

    __o | The lottery is a tax on those who fail to understand _`\(,_ | mathematics. (_)/ (_) |
     
  8. In article <[email protected]>,
    [email protected] says...

    >A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    >then, but is this something I should worry about? See
    >http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-1.jpg and
    >http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-2.jpg . Advice appreciated.

    I wouldn't want to be riding behind you. That is one nasty crack. I wouldn't risk riding on that
    crank. Since it is the left crank, you could probably find a replacement cheap.
    --------------
    Alex
     
  9. Jobst Brandt

    Jobst Brandt Guest

    Ed Swierk writes:

    > A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    > then, but is this something I should worry about?

    > See

    http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-1.jpg
    http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-2.jpg

    > Advice appreciated.

    Do not ride one more pedal stroke with that crank. That crack is all the way through the heel of the
    crank and since you don't have Lance Armstrong's dual pinch-bolt Shimano cranks, that are designed
    with a split. Take off those cranks right now. What makes you think this is a safe crank to ride?

    Jobst Brandt [email protected] Palo Alto CA
     
  10. Jobst Brandt

    Jobst Brandt Guest

    Dave Thompson writes:

    > That is not a piece of equipment I'd like to have on my bike. Can you imagine the crankarm coming
    > off under little power, your foot striking the ground and maybe getting caught in your rear
    > wheel. Ouch!

    THat's not the way it happens. Let me tell you, when a crank breaks, you are standing on the road
    with one foot and cannot run because you have a bicycle between your legs and the other foot most
    likely attached to the pedal. You WILL fall to the side on which the crank failed and if its a left
    crank you will dive under passing traffic if there is any.

    I've done it several times and was lucky to have no traffic. A ready-mix truck is possible. That's
    the real OUCH!

    Jobst Brandt [email protected] Palo Alto CA
     
  11. Jobst Brandt

    Jobst Brandt Guest

    David L. Johnson writes:

    > Don't worry. Replace the crank immediately instead. Imagine when it develops another crack, and
    > falls off on the downstroke while climbing. Hello, top tube.

    The proposed scenarios in this thread are entirely imagined, just as non-bicyclists have enormous
    fear of the handlebar stem and their genitals. It doesn't happen that way. When a crank breaks, the
    foot lands on the ground without incident but the rider, if traveling more than 10mph takes a dive
    to that side. You don't land on the top tube! However, that fear has given us 14inch seat posts and
    sloping down tubes to give a SAFER stand-over clearance.

    Where is bicycling going???

    Jobst Brandt [email protected] Palo Alto CA
     
  12. Ed Swierk wrote:
    > A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    > then, but is this something I should worry about?
    >
    > See http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-1.jpg and
    > http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-2.jpg .

    <FONT COLOR="RED><FONT SIZE="+6">

    DO NOT RIDE IT! THROW IT AWAY IMMEDIATELY!! YOU'VE BEEN LUCKY SO FAR, DON'T PUSH IT!!!

    </FONT></FONT>

    Sheldon "Rarely Shouts" Brown +------------------------------------+
    | Experience is a hard teacher, | because she gives the test first, | the lesson after. --
    | Vernon Law |
    +------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772
    FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
    http://captainbike.com http://sheldonbrown.com
     
  13. Ed Swierk

    Ed Swierk Guest

    Thanks to all for the advice. I'd never heard of cranks breaking, but I think I get the picture now.

    On Tue, 20 May 2003, Alex Rodriguez wrote:

    > Since it is the left crank, you could probably find a replacement cheap.

    My LBS wants $70 for a new Campy Veloce left crank. I pre-paid, and then found out that Nashbar
    sells the whole crankset (a triple) for $85. Oh well. It's my good LBS deed for the day.

    (More show & tell. Is it time for new chainrings? These aren't skipping but they look worn:
    http://cyclonite.stanford.edu/~eswierk/misc/chainrings.jpg)

    --Ed

    --
    Ed Swierk [email protected]
     
  14. Gregr

    Gregr Guest

    Depends on whether you like the taste of asphalt or concrete. As other posters here are saying, you
    need to replace that crank before riding your bike again.

    Take Jobst for example, he has broken several cranks and has gone down hard. You don't want to end
    up looking like him! He's the poster child for broken cranks...

    And when you replace the crank, don't forget to grease those tapers, or should you clean the tapers?
    I am not sure...

    May the loads be with you...

    G

    On Mon, 19 May 2003 15:11:21 -0700, Ed Swierk <[email protected]> wrote:

    >A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    >then, but is this something I should worry about?
    >
    >See http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-1.jpg and
    >http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-2.jpg .
    >
    >Advice appreciated.
    >
    >--Ed
     
  15. Matt Locker

    Matt Locker Guest

    Ed:

    I'm actually surprised you're asking. Is the risk of a crash worth it? How much will it cost to
    repair the bike, the teeth, how much pain will you have to endure to clean the grit out of your skin
    and then wait for the new skin to cover? Then there is the issue of when/where the failure occures.
    Say you fall in front of the semi going 65mph? You won't feel much, but your relatives family
    probably will. They would probably at that point say "Jeez, I wish he had just spent the money. I
    would have loaned it too him if he'd only asked!"

    So, what do you think? Should you replace it? I know what my answer would be.

    MOO, Matt

    Ed Swierk wrote:

    >A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse since
    >then, but is this something I should worry about?
    >
    >See http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-1.jpg and
    >http://cyclonite.stanford.edu/~eswierk/misc/crank-crack-2.jpg .
    >
    >Advice appreciated.
    >
    >--Ed
    >
     
  16. Ed-<< A few months ago I noticed a crack at the top of the left crank. It hasn't gotten any worse
    since then, but is this something I should worry about?

    yes, common on early left, lower end, crank arms from Campagnolo...Newer left cranks from Triples
    and lower end cranks had a lot more material there.

    Don't replace it if you don't mind breaking off a crank...

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  17. Robin Hubert

    Robin Hubert Guest

  18. On Tue, 20 May 2003 04:20:29 GMT, [email protected] wrote:

    >THat's not the way it happens. Let me tell you, when a crank breaks, you are standing on the road
    >with one foot and cannot run because you have a bicycle between your legs and the other foot most
    >likely attached to the pedal. You WILL fall to the side on which the crank failed and if its a left
    >crank you will dive under passing traffic if there is any.

    Is the falling part a function of speed? I've only broken one crank (right side, about 2" up from
    the pedal spindle), but didn't fall. I had just entered a bike path after making a sharp turn, and
    was travelling 10-15 mph, seated. All of a sudden my right foot was free (I thought I had broken the
    pedal), but the pedal and crank stub were still strapped to my foot when I looked down.

    John Henderson, New York City, USA
    =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
    "Let's roll!" -- Todd Beamer, 9/11/01 "After five and weekends" -- 711th SOS
    =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
     
  19. Jobst Brandt

    Jobst Brandt Guest

    John Henderson writes:

    >> THat's not the way it happens. Let me tell you, when a crank breaks, you are standing on the road
    >> with one foot and cannot run because you have a bicycle between your legs and the other foot most
    >> likely attached to the pedal. You WILL fall to the side on which the crank failed and if its a
    >> left crank you will dive under passing traffic if there is any.

    > Is the falling part a function of speed? I've only broken one crank (right side, about 2" up from
    > the pedal spindle), but didn't fall. I had just entered a bike path after making a sharp turn, and
    > was travelling 10-15 mph, seated. All of a sudden my right foot was free (I thought I had broken
    > the pedal), but the pedal and crank stub were still strapped to my foot when I looked down.

    You were seated. Most cranks break off in a high force instance and for most active riders, that's a
    standing sprint (away from a stop) or up a hill. The crank gradually develops the crack but since
    there is a wide span of forces applied, it is common for failure to occur at high stress and that is
    most often while standing, the dangerous contition.

    Jobst Brandt [email protected] Palo Alto CA
     
Loading...
Thread Status:
Not open for further replies.
Loading...