Crank crack

[Tim McNamara]

In article <[email protected]>, [email protected] wrote:

> 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'd hate to have had that happen standing on the pedals while descending at speed on bumpy ground.
Scary! Glad to hear the OP has a replacement crank.

 

[A Muzi]

As a result of top posting I can't parse this part correctly:
> 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.

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

That's way out of line. I just bought a Veloce left today. It really does cost me 62% of the cost of
a complete crankset. There is some serious glitch in Campagnolo's pricing structure apparently on
that part.

But it cannot possibly sell for $70 at any realistic margin. That is 78% of the entire crankset
price!! Ask your dealer to run the numbers once more and see if he doesn't agree he made an error.

--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

 

[Sergio Servadio]

On Wed, 21 May 2003 [email protected] wrote:
> 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.

I have always wondered: how do such high forces compare with the 'impact forces' the cranks
experience, while coasting downhill on the pedals, one hits a pothole?

A question for Jobst, or anyone else in fact.

Sergio Pisa

 

[Mark Hickey]

"A Muzi" <[email protected]> wrote:

>"Ed Swierk" <[email protected]> wrote in message
>news[email protected]...
>> 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)
>
>That's way out of line. I just bought a Veloce left today. It really does cost me 62% of the cost
>of a complete crankset. There is some serious glitch in Campagnolo's pricing structure apparently
>on that part.
>
>But it cannot possibly sell for $70 at any realistic margin. That is 78% of the entire crankset
>price!! Ask your dealer to run the numbers once more and see if he doesn't agree he made an error.

You got me curious - I just checked my distributor (QBP) pricing for crank arms and could't believe
what I saw. A Centaur LEFT crank arm costs 1.46x as much as the RIGHT crank arm! That's just odd...
Oh, and based on the price they get for it, I don't think the LBS is all that far off base (sadly).

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame

 

[Ed Swierk]

On Tue, 20 May 2003 [email protected] wrote:

> 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.

Wow.

Is this alarming anyone else besides me? Shouldn't important parts of bicycles be designed not to
fail catastrophically under normal use (i.e. riding them)?

There's no substitute for regular maintenance and safety checks, natch, but to this newbie, a crank
snapping in two seems to be well beyond normal wear-'n'-tear.

--Ed

--
Ed Swierk [email protected]

 

[Jobst Brandt]

Tim McNamara <[email protected]> writes:

>>> That is not a piece of equipment I'd like to have on my bike. Can you imagine the crank 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'd hate to have had that happen standing on the pedals while descending at speed on bumpy ground.
> Scary! Glad to hear the OP has a replacement crank.

Well, it's not bad because your CG is over the BB when standing, about seven inches behind the
leading pedal over which it would be if you were sprinting. Therefore, you have the ability to stand
on the remaining pedal as it descends staying centered under your body CG as both pedals were before
failure. The result is you can sit down and brake to a stop. I have also experienced that failure.
It isn't nearly as dangerous as when accelerating while standing.

Jobst Brandt [email protected] Palo Alto CA

 

[Chris Zacho "Th]

I wouldn't trust a cracked anything on a bike. Especially a high stress item like a crank arm.
Single arms (especially lefts) are cheap, especially a swap meets, if you really want to sav money.

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner

 

[Jobst Brandt]

Ed Swierk writes:

>> 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.

> Is this alarming anyone else besides me? Shouldn't important parts of bicycles be designed not to
> fail catastrophically under normal use (i.e. riding them)?

This is another item that James Annan might pursue, that of pedal attachment, because that is where
most cranks fail. As I have often written, we have left hand threads on left pedals for a reason,
that being that pedals always move in the crank even when tightened securely. Thier motion is
evident by visible fretting wear on the face of the crank from pedal contact. Besides, if
conventionsl cranks are used on tandems using reversed cranks, they loosen in use.

> There's no substitute for regular maintenance and safety checks, natch, but to this newbie, a
> crank snapping in two seems to be well beyond normal wear-'n'-tear.

In this case there is. After breaking one crank per year, over many years, I modified my pedal
attachment to have a 90 degree conical seat like lug nuts on automobile wheels. THese nuts formerly
had left hand threads before the conical lug nut was invented. I no longer have crank failures and
no longer make a weekly magnifying glass inspection of my cranks since making this modification. The
cranks have outlived previous ones nearly tenfold to now.

I have shown the cranks, how they were modified, and explained the concept to various crank
manufacturers, including Shimano higher management at InterBike 2002. They dismiss the concept
similarly to the comments we have heard about disc brake wheel separation.

Jobst Brandt [email protected] Palo Alto CA

 

[Jobst Brandt]

Sergio Servadio writes:

>> 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.

> I have always wondered: how do such high forces compare with the 'impact forces' the cranks
> experience, while coasting downhill on the pedals, one hits a pothole?

There are no impact loads on pedal cranks unless a pedal hits a rock. The load of one's body is
supported by a foot that is held roughly parallel to the road by muscles that do not transmit
mechanical shock in the frequencies of interest for metals. Imagine trying to drive a nail into a
board with the foot, using the cleat of a bicycle shoe placed on the nail head and lunging on it. I
think this makes visual the lack of impact.

Jobst Brandt [email protected] Palo Alto CA

 

[Benjamin Lewis]

jobst brandt wrote:

> I have shown the cranks, how they were modified, and explained the concept to various crank
> manufacturers, including Shimano higher management at InterBike 2002. They dismiss the concept
> similarly to the comments we have heard about disc brake wheel separation.

Perhaps a few lawsuits would do the trick.

--
Benjamin Lewis

A fool and his money are soon popular.

 

[Matt O'Toole]

<[email protected]> wrote in message news:[email protected]...

> I have shown the cranks, how they were modified, and
explained the
> concept to various crank manufacturers, including Shimano
higher
> management at InterBike 2002. They dismiss the concept
similarly to
> the comments we have heard about disc brake wheel
separation.

Well, if they change it, they admit the original design was flawed. Surely you've seen that
phenomena...

Matt O.

 

[Sergio Servadio]

On Wed, 21 May 2003 [email protected] wrote:

> There are no impact loads on pedal cranks unless a pedal hits a rock. The load of one's body is
> supported by a foot that is held roughly parallel to the road by muscles that do not transmit
> mechanical shock in the frequencies of interest for metals. Imagine trying to drive a nail into a
> board with the foot, using the cleat of a bicycle shoe placed on the nail head and lunging on it.
> I think this makes visual the lack of impact.

I see what you mean, and in a sense I agree (since that's the correct way to absorb shocks in fact),
but only partly so. Why, else, did I end up having sore feet, from the cleats through much too thin
shoe soles, at the bottom of long downhill descents?

Sergio Pisa

 

[Jobst Brandt]

Sergio Servadio writes:

>> There are no impact loads on pedal cranks unless a pedal hits a rock. The load of one's body is
>> supported by a foot that is held roughly parallel to the road by muscles that do not transmit
>> mechanical shock in the frequencies of interest for metals. Imagine trying to drive a nail into a
>> board with the foot, using the cleat of a bicycle shoe placed on the nail head and lunging on
>> it. I think this makes visual the lack of impact.

> I see what you mean, and in a sense I agree (since that's the correct way to absorb shocks in
> fact), but only partly so. Why, else, did I end up having sore feet, from the cleats through much
> too thin shoe soles, at the bottom of long downhill descents?

Concentrated pressure causes pain and sometimes damage. This is not to be confused with impact.
It is like sitting on, for instance, a golf ball. It hurts sooner or later, no matter how gently
you sit down.

Jobst Brandt [email protected] Palo Alto CA

 

[Squid-In-Traini]

<[email protected]> wrote in message news:[email protected]...
> Ed Swierk writes:
>
> >> 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 it just me or does the crack look like a synarthrodial joint?

--
Phil, Squid-in-Training

 

[Robin Hubert]

"Phil, Squid-in-Training" <[email protected]> wrote in message
news:r3%[email protected]...
>
> <[email protected]> wrote in message
> news:[email protected]...
> > Ed Swierk writes:
> >
> > >> 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 it just me or does the crack look like a synarthrodial joint?
>

Like the ones in the skull that separate when that crank fails?

--
Robin Hubert <[email protected]

 

[Michael J. Ande]

Hello all,

I am going to Las Vegas this weekend on a business trip and I would like to ride while there. Does
anyone know of an LBS there that rents high quality road bikes?

Thanks for the help, Michael

 

[Andrew Martin]

"Michael J. Anderson" <[email protected]> wrote in message
news:<[email protected]>...
> Hello all,
>
> I am going to Las Vegas this weekend on a business trip and I would like to ride while there. Does
> anyone know of an LBS there that rents high quality road bikes?
>
> Thanks for the help, Michael

http://www.mcghies.com/ Got me on a decent Trek 2000. Worked fine for the day.

I used them just a few weeks ago. The ride to Red Rocks, then up to
Mt. Potassi is great. The air is really dry, you burn a lot faster than you think (LOTS OF
SUNSCREEN), and you drink a ton. I bought 3 or 4 liters of water along the way in addition to my
bottles. One thing to consider though - it's a false flat all the way out of town to the west.
Don't get discouraged - I was totally ****** that it took me so long to get out of town and up
the hills. I rode out 3.5 hours, and made it home in just over 1 hour (didn't retrace the
red-rocks on the way home as it is One way road).

email me if you have more questions - it was a great ride.

 

[Claire Petersky]

"Michael J. Anderson" <[email protected]> wrote in message
news:<[email protected]>...
> Hello all,
>
> I am going to Las Vegas this weekend on a business trip and I would like to ride while there. Does
> anyone know of an LBS there that rents high quality road bikes?

If you go here: http://www.vegasbikeclub.org/ and click on the FAQ you'll find a listing of
rental places.

My husband is in Vegas even as I type this now (we go out there all the time because his parents
retired out there) and he rented a bike I think at McGhies Ski, Bike and Board for general
transportation (in that heat!!) and also to do a little spin out to Lake Mead and Henderson and
whatnot. I don't know if the bike was "high quality" by your standards -- he described it to me as
"a $1500 machine", but didn't tell me what make it was. Also, we rented road bikes (Trek
1200s) at Blue Diamond Bike Out Post last year with no complaints.

Read my post at http://tinyurl.com/cwuq for a trip report for that ride last summer if you want to
get a flavor of riding in the heat!

Warm Regards,

Claire Petersky ([email protected]) Home of the meditative cyclist at:
http://home.earthlink.net/~cpetersky/Welcome.htm

 

[Mike Iglesias]

In article <[email protected]>, Claire Petersky
<[email protected]> wrote:
>If you go here: http://www.vegasbikeclub.org/ and click on the FAQ you'll find a listing of
>rental places.

You may also find that they have a ride going while you're there. My wife was in Vegas for a
conference so I went along and brought my bike. LVBC had a ride on a thursday morning that I went
on, and I had a good time. We started out around 8am and finished around 11am. It was about 102
degrees by the time we got back. I had used up most of the water in my camelback by the end of the
ride, so make sure you have a way to carry a lot of water with you, or stop often to get more.

--
Mike Iglesias Email: [email protected] University of California, Irvine phone: 949-824-6926
Network & Academic Computing Services FAX: 949-824-2069

 

[Michael J. Ande]

Just wanted to say thanks to all those who replied with the McGhies LBS recommendation. As the
following post, we also rented the Trek 2000s for the day, and although not a great bike, it was the
best bike we have ever been able to find as a rental, and it made for a great day of riding.

I highly recommend McGhies for anyone wanting a rental road bike while in Vegas.

Thanks again, Michael

On 28 May 2003, Andrew Martin wrote:

> "Michael J. Anderson" <[email protected]> wrote in message
> news:<[email protected]>...
> > Hello all,
> >
> > I am going to Las Vegas this weekend on a business trip and I would like to ride while there.
> > Does anyone know of an LBS there that rents high quality road bikes?
> >
> > Thanks for the help, Michael
>
> http://www.mcghies.com/ Got me on a decent Trek 2000. Worked fine for the day.
>
> I used them just a few weeks ago. The ride to Red Rocks, then up to
> Mt. Potassi is great. The air is really dry, you burn a lot faster than you think (LOTS OF
> SUNSCREEN), and you drink a ton. I bought 3 or 4 liters of water along the way in addition to
> my bottles. One thing to consider though - it's a false flat all the way out of town to the
> west. Don't get discouraged - I was totally ****** that it took me so long to get out of town
> and up the hills. I rode out 3.5 hours, and made it home in just over 1 hour (didn't retrace
> the red-rocks on the way home as it is One way road).
>
> email me if you have more questions - it was a great ride.