Crank crack

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]

 

"Ed Swierk" <[email protected]> wrote in message
news[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!

 

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

 

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.

 

>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

 

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

 

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. (_)/ (_) |

 

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

 

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

 

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

 

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

 

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

 

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]

 

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

 

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
>

 

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"

 

You ARE joking.

--
Robin Hubert <[email protected]>

"Ed Swierk" <[email protected]> wrote in message
news[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]

 

In article <[email protected]>,
[email protected] says...

>(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)

I can't tell by eyeballing chainrings. Especially nowadays with chainrings that are machined to give
better shifting. If your did not ride with a worn chain, your rings are probably ok.
-----------------
Alex __O _-\<,_ (_)/ (_)

 

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
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

 

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