Snapped Bottom Bracket Spindle?

[Prague Tech]

Hey All,

I was working my regular pedicab driver shift the other day,
accelerating from a stop light with 3 large guys seated in my trailer
type pedicab. I sort of jumped forward in an unexpected way and heard
a scattering, clank-clank. I then noticed the my left pedal was
missing. Then I noticed my left crank arm, and the end of the bottom
bracket spindle that would normally keep the afore mentioned parts
attached were gone too. Upon inspection, the missing bottom bracket
stub was still pressed into the crank arm that I was holding in my
hands. In spite of my displeasure of not being able to earn more
money that night dragging drunken louts to their next whisky bar, I
was amused by the massive power I exhibited by ripping the crank
nipple right off.

So here is my question:
Was it really my massive lower body prowess that killed this BB
spindle? Or is it that Shimano is making crappy spindles that shread
after 5 months? Or is the pedicabbing I do on this bike just that
hard on the torquey bits?

Perhaps it was a combination of the three. I bring this to the R.B.T
group as none of my pedicabber buddies have had this particular
mechanical failure before. Chalo on the other hand has done it a few
times before resulting in his oh-so-fashionable grillz. (him 300+ lbs)

-Ken Cameron
humble neighborhood pedicabber

 

[[email protected]]

Ken Cameron writes:

> I was working my regular pedicab driver shift the other day,
> accelerating from a stop light with 3 large guys seated in my
> trailer type pedicab. I sort of jumped forward in an unexpected way
> and heard a scattering, clank-clank. I then noticed the my left
> pedal was missing. Then I noticed my left crank arm, and the end of
> the bottom bracket spindle that would normally keep the afore
> mentioned parts attached were gone too. Upon inspection, the
> missing bottom bracket stub was still pressed into the crank arm
> that I was holding in my hands. In spite of my displeasure of not
> being able to earn more money that night dragging drunken louts to
> their next whisky bar, I was amused by the massive power I exhibited
> by ripping the crank nipple right off.

> So here is my question:

> Was it really my massive lower body prowess that killed this BB
> spindle? Or is it that Shimano is making crappy spindles that
> shred after 5 months? Or is the pedicabbing I do on this bike just
> that hard on the torquey bits?

> Perhaps it was a combination of the three. I bring this to the
> R.B.T group as none of my pedicabber buddies have had this
> particular mechanical failure before. Chalo on the other hand has
> done it a few times before resulting in his oh-so-fashionable
> grillz. (him 300+ lbs)

Although such spindles are usually hardened so they can take the high
contact stress of their bearing balls, this is most surely a fatigue
failure that was the summation of many loaded torque repetitions.
You'll note that only the torque of the left foot goes through the
spindle, the right foot going directly into the chain. The fracture
should be a slightly helical crack, part of which is at 45° to the
spindle.

Low quality material and/or heat treatment.

Jobst Brandt

 

[jim beam]

Prague Tech wrote:
> Hey All,
>
> I was working my regular pedicab driver shift the other day,
> accelerating from a stop light with 3 large guys seated in my trailer
> type pedicab. I sort of jumped forward in an unexpected way and heard
> a scattering, clank-clank. I then noticed the my left pedal was
> missing. Then I noticed my left crank arm, and the end of the bottom
> bracket spindle that would normally keep the afore mentioned parts
> attached were gone too. Upon inspection, the missing bottom bracket
> stub was still pressed into the crank arm that I was holding in my
> hands. In spite of my displeasure of not being able to earn more
> money that night dragging drunken louts to their next whisky bar, I
> was amused by the massive power I exhibited by ripping the crank
> nipple right off.
>
> So here is my question:
> Was it really my massive lower body prowess that killed this BB
> spindle? Or is it that Shimano is making crappy spindles that shread
> after 5 months? Or is the pedicabbing I do on this bike just that
> hard on the torquey bits?

impossible to say for sure without quality pics of the installation and
the break. shimano are not known for spindle breakage so i'm interested
to see if there was any damage to it that could have initiated metal
fatigue.


>
> Perhaps it was a combination of the three. I bring this to the R.B.T
> group as none of my pedicabber buddies have had this particular
> mechanical failure before. Chalo on the other hand has done it a few
> times before resulting in his oh-so-fashionable grillz. (him 300+ lbs)
>
> -Ken Cameron
> humble neighborhood pedicabber
>

 

[Jambo]

"jim beam" <[email protected]> wrote in message
news:[email protected]...
> Prague Tech wrote:

>> So here is my question:
>> Was it really my massive lower body prowess that killed this BB
>> spindle? Or is it that Shimano is making crappy spindles that shread
>> after 5 months? Or is the pedicabbing I do on this bike just that
>> hard on the torquey bits?
>
> impossible to say for sure without quality pics of the installation and
> the break. shimano are not known for spindle breakage so i'm interested
> to see if there was any damage to it that could have initiated metal
> fatigue.

And what, give us all the "benefit" of your "metarials skool" training? No
thanks, beamboy, he might as well ask a 3yo.

 

[Lou Holtman]

Jambo wrote:
> "jim beam" <[email protected]> wrote in message
> news:[email protected]...
>> Prague Tech wrote:
>
>>> So here is my question:
>>> Was it really my massive lower body prowess that killed this BB
>>> spindle? Or is it that Shimano is making crappy spindles that shread
>>> after 5 months? Or is the pedicabbing I do on this bike just that
>>> hard on the torquey bits?
>> impossible to say for sure without quality pics of the installation and
>> the break. shimano are not known for spindle breakage so i'm interested
>> to see if there was any damage to it that could have initiated metal
>> fatigue.
>
> And what, give us all the "benefit" of your "metarials skool" training? No
> thanks, beamboy, he might as well ask a 3yo.
>
>


Boy, you are annoying.

Lou
--
Posted by news://news.nb.nu (http://www.nb.nu)

 

[Prague Tech]

On Oct 22, 11:25 pm, jim beam <[email protected]> wrote:
>
> impossible to say for sure without quality pics of the installation and
> the break. shimano are not known for spindle breakage so i'm interested
> to see if there was any damage to it that could have initiated metal
> fatigue.

>I will try to get some pics of the busted bits before the reinstall. As for the install, >It came on this bike from a very trustworthy LBS 5 monthsago. The BB had not >been removed. I had tightened the crank bolts afterpulling the crank and adding >new chain ring.

>Although such spindles are usually hardened so they can take the high
>contact stress of their bearing balls, this is most surely a fatigue
>failure that was the summation of many loaded torque repetitions.
>You'll note that only the torque of the left foot goes through the
>spindle, the right foot going directly into the chain. The fracture
>should be a slightly helical crack, part of which is at 45° to the
>spindle.

>Low quality material and/or heat treatment.

>Jobst Brandt

You called it.

 

[[email protected]]

On Oct 22, 12:45 pm, Prague Tech <[email protected]> wrote:

> So here is my question:
> Was it really my massive lower body prowess that killed this BB
> spindle? Or is it that Shimano is making crappy spindles that shread
> after 5 months? Or is the pedicabbing I do on this bike just that
> hard on the torquey bits?
>
> Perhaps it was a combination of the three. I bring this to the R.B.T
> group as none of my pedicabber buddies have had this particular
> mechanical failure before. Chalo on the other hand has done it a few
> times before resulting in his oh-so-fashionable grillz. (him 300+ lbs)
>
> -Ken Cameron
> humble neighborhood pedicabber

http://pardo.net/bike/pic/fail-001/FAIL-001.html

Scroll down to the bottom for the spindles. If a spindle's going
to fail, it seems like pedicabbing is a likely place - you probably
exert a frequent high startup torque. The BB spindle is a little
undersized for high load applications. The expensive cure for
this is a different spindle system. Other than that, it's possible
that avoiding the cheaper BBs helps (I have no evidence that
better BBs are made from stronger stuff, though) and periodic
inspection might help, though that is a nuisance with BB spindles.

Ben

 

[Jambo]

"Lou Holtman" <[email protected]> wrote in message
news:[email protected]...
> Jambo wrote:
>> "jim beam" <[email protected]> wrote in message
>> news:[email protected]...
>>> Prague Tech wrote:
>>
>>>> So here is my question:
>>>> Was it really my massive lower body prowess that killed this BB
>>>> spindle? Or is it that Shimano is making crappy spindles that shread
>>>> after 5 months? Or is the pedicabbing I do on this bike just that
>>>> hard on the torquey bits?
>>> impossible to say for sure without quality pics of the installation and
>>> the break. shimano are not known for spindle breakage so i'm interested
>>> to see if there was any damage to it that could have initiated metal
>>> fatigue.
>>
>> And what, give us all the "benefit" of your "metarials skool" training?
>> No thanks, beamboy, he might as well ask a 3yo.
>>
>>
>
>
> Boy, you are annoying.

A bonus effect with beamboy. But what's it got to do with you?

 

[Ozark Bicycle]

On Oct 23, 4:04 pm, "Jambo" <[email protected]> wrote:
> "Lou Holtman" <[email protected]> wrote in message
>
> news:[email protected]...
>
>
>
> > Jambo wrote:
> >> "jim beam" <[email protected]> wrote in message
> >>news:[email protected]...
> >>> Prague Tech wrote:
>
> >>>> So here is my question:
> >>>> Was it really my massive lower body prowess that killed this BB
> >>>> spindle? Or is it that Shimano is making crappy spindles that shread
> >>>> after 5 months? Or is the pedicabbing I do on this bike just that
> >>>> hard on the torquey bits?
> >>> impossible to say for sure without quality pics of the installation and
> >>> the break. shimano are not known for spindle breakage so i'm interested
> >>> to see if there was any damage to it that could have initiated metal
> >>> fatigue.
>
> >> And what, give us all the "benefit" of your "metarials skool" training?
> >> No thanks, beamboy, he might as well ask a 3yo.
>
> > Boy, you are annoying.
>
> A bonus effect with beamboy. But what's it got to do with you?


You *are* playing to the audience, aren't you, Jambozo?

 

[jim beam]

Prague Tech wrote:
> On Oct 22, 11:25 pm, jim beam <[email protected]> wrote:
>> impossible to say for sure without quality pics of the installation and
>> the break. shimano are not known for spindle breakage so i'm interested
>> to see if there was any damage to it that could have initiated metal
>> fatigue.
>
>> I will try to get some pics of the busted bits before the reinstall. As for the install, >It came on this bike from a very trustworthy LBS 5 months ago. The BB had not >been removed. I had tightened the crank bolts after pulling the crank and adding >new chain ring.
>
>> Although such spindles are usually hardened so they can take the high
>> contact stress of their bearing balls, this is most surely a fatigue
>> failure that was the summation of many loaded torque repetitions.
>> You'll note that only the torque of the left foot goes through the
>> spindle, the right foot going directly into the chain. The fracture
>> should be a slightly helical crack, part of which is at 45� to the
>> spindle.
>
>> Low quality material and/or heat treatment.

if that were true, it would be a common occurrence. but it's not. and
it's not excess torque either - the rider can exert no more torque on
the crank end of a pedicab than on any other bike.


>
>> Jobst Brandt
>
> You called it.
>