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)
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.
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So here is my question:
Quoted message said:
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?
Quoted message said:
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.
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.
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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)
"jim beam" <[email hidden]> wrote in message news:[email hidden]...
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Prague Tech wrote:
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Quoted message said:
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.
"jim beam" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Prague Tech wrote:
Quoted message said:
Quoted message said:
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.
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.
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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.
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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.
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)
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.
"Lou Holtman" <[email hidden]> wrote in message news:[email hidden]...
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Jambo said:
"jim beam" <[email hidden]> wrote in message news:[email hidden]...
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Prague Tech wrote:
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> 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?
"jim beam" <[email hidden]> wrote in message news:[email hidden]... > Prague Tech wrote:
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Quoted message said:
>> 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.
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And what, give us all the "benefit" of your "metarials skool" training? No thanks, beamboy, he might as well ask a 3yo.
Quoted message said:
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?
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.
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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.
Quoted message said:
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.
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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.
