ISIS BB failures

Would some knowledgable person look at that shorn cross-
section of spindle and comment whether that looks like cast
or cold-forged steel?

Thanks, Tim

"john riley" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

FYI:

sheldonbrown.comfsabb.htmlOpen ↗

At least one other failure was reported on BROL

John Riley

I don't see that particular model of BB listed on their
current web site; but according to a 2002 FSA catalog I
have, their "Ultimax Xtreme" BB had a "Forged hollow
chromoly spindle".

Rick Moll

TimH said:

Would some knowledgable person look at that shorn cross-
section of spindle and comment whether that looks like
cast or cold-forged steel?

Thanks, Tim

"john riley" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

FYI:

sheldonbrown.comfsabb.htmlOpen ↗

At least one other failure was reported on BROL

John Riley

Spindles can be a real pain in the backside if they are
poorly designed .

Had a spindle on a piece of gear that under normal
circumstance would go from 3600RPM <not bicycle related
obviously> to a full stop. I do mean full stop! This thing
might have done maybe a 1/16th of a turn after the brake
command was initiated. 3600rpm to 0 in 1/16 of a turn is
freaky fast stopping!

AWESOME BRAKE!!!

Unfortunately the spindle had been poorly designed, and
would shear at the only spot that had a 90 degree depth
change. 1 inch to 5/8ths. We might get 5 to 10 minutes
of use out of the thing on 1 to 30 second bursts before
it snapped.

Had the spindle been designed with a gradual change from 1
inch down to 5/8ths of an inch over a 3/8ths inch length
rather than 1 inch down to 5/8ths of an inch at a 90 degree
over almost MAYBE a 10/1000th of an inch we would not have
sheared so many spindles at $1500 bucks a piece.

This may be the problem with this spindle as well, although
we are not looking at 3600 RPM obviously, and not stopping
on a dime either, but were there sufficient force put on the
spindle from a direction that it is weak in, it would be the
right way to shear it...

Enough force put on the peddle while pushing down could do
this, IF the spindle had as they call it a stress riser, or
an area where the diameter changes dramatically rather than
gradually...

What do I know... I am an electronics/avionics tech not a
mechanical engineer...

TimH said:

Would some knowledgable person look at that shorn cross-
section of spindle and comment whether that looks like cast
or cold-forged steel?

Thanks, Tim

"john riley" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

FYI:

sheldonbrown.comfsabb.htmlOpen ↗

At least one other failure was reported on BROL

John Riley

Please delete the ".removethis" in my email address as this
is there for spam control. Thanks!

I believe Tim wasn't asking for someone to look at their Web
site (d'oh!) . . .

Rick Moll <[email hidden]> wrote in message news:<b-
[email hidden]>...

Quoted message said:

I don't see that particular model of BB listed on their
current web site . . .

Quoted message said:

TimH said:

Would some knowledgable person look at that shorn cross-
section of spindle and comment whether that looks like
cast or cold-forged steel?

Quoted message said:

Quoted message said:

Quoted message said:

>>
sheldonbrown.comfsabb.htmlOpen ↗

TimH said:

Would some knowledgable person look at that shorn cross-
section of spindle and comment whether that looks like
cast or cold-forged steel?

It is hard (impossible?) to tell from a fracture surface.
Microstructure is usually observed by machining and then
polishing a flat surface that is viewed under a microscope.
In addition, if heat treatment is applied after the casting
or forging, the microstructure will be altered so it might
not be possible to tell (and the effects of heat treating
will vary significantly with alloy type).

--
Tom Sherman – Quad City Area