cracked Shimano rear hub

Andy Heninger said:

My rear hub (Shimano XT) has developed a crack in the body, going about
two thirds of the way around.

Here's a picture
http://barbwired.com/andy/ngpix/hub_crack.jpg

wow! cool!

Quoted message said:

Has anyone seen this type of failure before? I've seen and heard of
plenty of cracked bicycle parts, but not one like this.

The wheel has about 9000 miles on it.

I went looking for problems when the wheel started making clicking and
popping noises when climbing hills. I don't know how long it took the
crack to grow to this size, I don't normally pay much attention to the
hubs, and the crack was much less visible before wiping off the
accumulated dirt.

The axle still turns smoothly and freely, and there is no sign of it
being bent.

Weird

-- Andy

since it's broken at about the point where the freehub body screw ends,
i'd guess either a problem with the internal hub shell machining or
maybe even excess freehub screw torque overstressing it. the former is
unlikely since shimano make loads of these things and this type of
failure is rare. the latter is possible if the freehub has been removed
for cleaning.

either way, there's no repair possible, only replacement.

On Wed, 13 Sep 2006 21:00:02 -0700, Andy Heninger <[email hidden]>

Quoted message said:

My rear hub (Shimano XT) has developed a crack in the body, going about
two thirds of the way around.

Here's a picture
http://barbwired.com/andy/ngpix/hub_crack.jpg

Has anyone seen this type of failure before? I've seen and heard of
plenty of cracked bicycle parts, but not one like this.

The wheel has about 9000 miles on it.

I went looking for problems when the wheel started making clicking and
popping noises when climbing hills. I don't know how long it took the
crack to grow to this size, I don't normally pay much attention to the
hubs, and the crack was much less visible before wiping off the
accumulated dirt.

The axle still turns smoothly and freely, and there is no sign of it
being bent.

I suspect that if you were to dissect the corpse (and make no mistake,
that hub is dead and neads to be replaced) you would discover that the
crack is right at the end of either the hollow bolt that holds the
body on to the hub, or it's at the end of the counterbore for that
bolt. I'd expect it to be at the former point, myself. I've noticed
that there's been a bit of variation in the wall thickness of the
Shimano hubs in that area; some are much more robust than others.

I guess this one was a poor compromise between weight and strength.

As for why it failed at all, I'd have to ask if you do a lot of
climbing out of the saddle in low gears on steep grades. The only
potential reason I can think of would be that the hub was being flexed
by the loading created in that situation.

--
Typoes are a feature, not a bug.
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Andy Heninger said:

My rear hub (Shimano XT) has developed a crack in the body, going about
two thirds of the way around.

Here's a picture
http://barbwired.com/andy/ngpix/hub_crack.jpg

Has anyone seen this type of failure before? I've seen and heard of
plenty of cracked bicycle parts, but not one like this.

The wheel has about 9000 miles on it.

I went looking for problems when the wheel started making clicking and
popping noises when climbing hills. I don't know how long it took the
crack to grow to this size, I don't normally pay much attention to the
hubs, and the crack was much less visible before wiping off the
accumulated dirt.

The axle still turns smoothly and freely, and there is no sign of it
being bent.

Weird

-- Andy

If/when you disassemble it, it'd be interesting if you took note of
whether the bolt that holds the freehub body onto the hub shell seemed
loose, tight, or neither (they're normally a quite high-torque item).
Has the freehub body on this hub ever been removed?

Andy Heninger said:

My rear hub (Shimano XT) has developed a crack in the body, going about
two thirds of the way around.

Here's a picture
http://barbwired.com/andy/ngpix/hub_crack.jpg

Has anyone seen this type of failure before? I've seen and heard of
plenty of cracked bicycle parts, but not one like this.

The wheel has about 9000 miles on it.

www.m-gineering.nl/oopsg.htm

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Andy Heninger said:

My rear hub (Shimano XT) has developed a crack in the body, going about
two thirds of the way around.

Here's a picture
http://barbwired.com/andy/ngpix/hub_crack.jpg

Has anyone seen this type of failure before? I've seen and heard of
plenty of cracked bicycle parts, but not one like this.

The wheel has about 9000 miles on it.

I went looking for problems when the wheel started making clicking and
popping noises when climbing hills. I don't know how long it took the
crack to grow to this size, I don't normally pay much attention to the
hubs, and the crack was much less visible before wiping off the
accumulated dirt.

The axle still turns smoothly and freely, and there is no sign of it
being bent.

Weird

Thank you. There's nothing we like better than pictures of bike parts broken in
new and novel ways.

That is indeed an interesting one.

Now all ya need is a little JB Weld and ....

Ron

M-gineering said:

Andy Heninger said:

My rear hub (Shimano XT) has developed a crack in the body, going
about two thirds of the way around.

Here's a picture
http://barbwired.com/andy/ngpix/hub_crack.jpg

Has anyone seen this type of failure before? I've seen and heard of
plenty of cracked bicycle parts, but not one like this.

The wheel has about 9000 miles on it.

www.m-gineering.nl/oopsg.htm

great collection!

RonSonic said:

Now all ya need is a little JB Weld and ....

Man, that's just what I was thinking!

Regards,
Anthony

"Anthony DeLorenzo" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

RonSonic said:

Now all ya need is a little JB Weld and ....

Man, that's just what I was thinking!

Regards,
Anthony

Actually I was thinking of aluminum solder and a gas torch myself.
:-)

But JB-Weld is a good one too.
Humm, the epoxy resin you use to glue golf club heads to their shafts might
be even better though.

jim beam said:

Andy Heninger said:

My rear hub (Shimano XT) has developed a crack in the body, going
about two thirds of the way around.

Quoted message said:

since it's broken at about the point where the freehub body screw ends,
i'd guess either a problem with the internal hub shell machining or
maybe even excess freehub screw torque overstressing it. the former is
unlikely since shimano make loads of these things and this type of
failure is rare. the latter is possible if the freehub has been removed
for cleaning.

Nope, the freehub body has never been removed. The hub was purchased new.

Quoted message said:

either way, there's no repair possible, only replacement.

Indeed. I'm just glad it didn't completely fail while riding it. I'm
not sure what would have happened if it had.

Werehatrack said:

As for why it failed at all, I'd have to ask if you do a lot of
climbing out of the saddle in low gears on steep grades. The only
potential reason I can think of would be that the hub was being flexed
by the loading created in that situation.

It was indeed ridden mostly in the hills (roads only), some of which
have reasonably steep bits (>15%), although grades that steep mostly are
over quite short distances. I weigh about 195 lbs. Usual climbing
gear is 42x30.

M-gineering said:

www.m-gineering.nl/oopsg.htm

Nice pictures! Interesting that your picture of a hub with the same
failure is also a Shimano XT. I wonder if that model was weak.

Thank you, everyone, for your comments,

-- Andy

Earl Bollinger said:

"Anthony DeLorenzo" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

RonSonic said:

Now all ya need is a little JB Weld and ....

Quoted message said:

Quoted message said:

Man, that's just what I was thinking!

Quoted message said:

Actually I was thinking of aluminum solder and a gas torch myself.
:-)

But JB-Weld is a good one too.
Humm, the epoxy resin you use to glue golf club heads to their shafts might
be even better though.

Carbon fiber reinforced epoxy. Adds bling to any hub!

--
Dave
dvt at psu dot edu

Everyone confesses that exertion which brings out all the powers of body
and mind is the best thing for us; but most people do all they can to
get rid of it, and as a general rule nobody does much more than
circumstances drive them to do. -Harriet Beecher Stowe, abolitionist and
novelist (1811-1896)

I had a pedal break like that what happened is the slotted washer
stripped out and over tightened the bearings. Was the hub running free?
I'm using a alivio hub with 20000 miles on it right now the back wheel
caries 150 lbs.