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DANGER: Trek multitrack 7300 (hybrid) aluminum bracket sheers off, rips apart entire rear end of bike



 
 
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  #1  
Old March 28th 05, 04:16 AM
Dan
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Posts: n/a
Default DANGER: Trek multitrack 7300 (hybrid) aluminum bracket sheers off, rips apart entire rear end of bike

Hi,

Because this is a hybrid I'm not sure whether to place it in racing or
off-road. But here goes my story.

Saturday afternoon I was riding along a clean flat nature trail; no
sticks in the gears, no nothing. I was going at an even speed of
about 20-25mph in the next-highest gear when all of a sudden I hear a
*SNAP*, then something smashed into the rear spokes, causing an almost
instant stop. I was lucky I wasn't going downhill when this occurred,
or I would've flown over the handlebars.

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue. The shifter mechanism
ripped off the aluminum frame, got caught in the rear spokes, and
destroyed the entire rear end of the bike. Several spokes are broken
and/or bent. The shifter mechanism is bent in several places, the
shifter wire is shredded, and the front crank apparatus also has some
damage due to the sudden awkward pull on the chain.

I was not happy. I had to walk 8 miles home while contending with a
pair of minor stress fractures in the legs (I was biking because I
can't run for the moment). I've contacted the dealer but so far no
reply. This $420 bike is just barely over 2 years old, with less than
500 miles on it. I expected to get more than a dollar per mile for
this bike, and I'm really not happy with Trek's poor design of this
frame and model.

If the dealer or Trek will support the repair of this obvious
manufacturer's defect, I will keep you apprised.

Dan

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  #2  
Old March 28th 05, 05:27 PM
MagillaGorilla
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Default

Dan wrote:

Hi,

Because this is a hybrid I'm not sure whether to place it in racing or
off-road. But here goes my story.

Saturday afternoon I was riding along a clean flat nature trail; no
sticks in the gears, no nothing. I was going at an even speed of
about 20-25mph in the next-highest gear when all of a sudden I hear a
*SNAP*, then something smashed into the rear spokes, causing an almost
instant stop. I was lucky I wasn't going downhill when this occurred,
or I would've flown over the handlebars.

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue. The shifter mechanism
ripped off the aluminum frame, got caught in the rear spokes, and
destroyed the entire rear end of the bike. Several spokes are broken
and/or bent. The shifter mechanism is bent in several places, the
shifter wire is shredded, and the front crank apparatus also has some
damage due to the sudden awkward pull on the chain.

I was not happy. I had to walk 8 miles home while contending with a
pair of minor stress fractures in the legs (I was biking because I
can't run for the moment). I've contacted the dealer but so far no
reply. This $420 bike is just barely over 2 years old, with less than
500 miles on it. I expected to get more than a dollar per mile for
this bike, and I'm really not happy with Trek's poor design of this
frame and model.

If the dealer or Trek will support the repair of this obvious
manufacturer's defect, I will keep you apprised.

Dan



Dan,

Given that TREK uses CAD/CAM and extensive quality control to design its
bikes, the metal fatigue on the derailleur hanger was most likely due to
damage that occurred in shipping or when the 16 year old mechanic who
put the bike together at the shop you got it from took it for a spin and
mashed it against a curb or something (believe it or not teenagers who
make minimum wage do stupid stuff like that).

One of the most common things in a crash is for the derailluer hanger to
get bent. And the way most people "fix" it is to bend it back, not
realizing that doing so causes substantial yet invisible metal fatigue.

So calm down on the CONSUMER PRODUCT WARNING thing unless you know for a
fact that defect originated in the manufacturing process.

Thanks,

Magilla

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  #3  
Old March 28th 05, 10:16 PM
Werehatrack
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On Sun, 27 Mar 2005 21:16:11 CST, Dan may have
said:

Hi,

Because this is a hybrid I'm not sure whether to place it in racing or
off-road. But here goes my story.

Saturday afternoon I was riding along a clean flat nature trail; no
sticks in the gears, no nothing. I was going at an even speed of
about 20-25mph in the next-highest gear when all of a sudden I hear a
*SNAP*, then something smashed into the rear spokes, causing an almost
instant stop. I was lucky I wasn't going downhill when this occurred,
or I would've flown over the handlebars.

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue. The shifter mechanism
ripped off the aluminum frame, got caught in the rear spokes, and
destroyed the entire rear end of the bike.


I find a different analysis more plausible; the rear derailleur cage
is much more likely to have snagged in the spokes, following the wheel
around and ripping the der support from the dropout in the process.
The der support tab has so little strain on it that it will not fail
due to "metal fatigue" even after an extremely long period in service.
There are at least three other ways by which the cited failure could
occur in my experience.

Several spokes are broken
and/or bent.


Quite typical of a spokejam due to der cage snagging.

The shifter mechanism is bent in several places, the
shifter wire is shredded, and the front crank apparatus also has some
damage due to the sudden awkward pull on the chain.


This should tell you something. Had the der mounting tab merely
failed, the der would have dropped off and hung from the chain, but
would not have been likely to get into the spokes; the der has to be
firmly mounted and the der cage extended (which won't be the case if
the der's mount breaks) in order for the cage to be able to grab the
spokes.

I was not happy. I had to walk 8 miles home while contending with a
pair of minor stress fractures in the legs (I was biking because I
can't run for the moment). I've contacted the dealer but so far no
reply. This $420 bike is just barely over 2 years old, with less than
500 miles on it. I expected to get more than a dollar per mile for
this bike, and I'm really not happy with Trek's poor design of this
frame and model.

If the dealer or Trek will support the repair of this obvious
manufacturer's defect, I will keep you apprised.


I suspect that failure analysis will determine that either the der had
been bent prior to the incident, putting its cage swing path into the
conincal region of the drive-side spokes, or that the der was stiff
due to congealed lubricant producing a motion pattern that put the der
into the spokes. I have had both types of failure occur; neither
would be a warranty matter.

Keep us informed in any event; it will be instructive for all
concerned if there's an actual defect involved.

--
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Typoes are not a bug, they're a feature.
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  #4  
Old March 28th 05, 10:21 PM
Carl Sundquist
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Default


"Dan" wrote in message
...
Hi,

Because this is a hybrid I'm not sure whether to place it in racing or
off-road. But here goes my story.

Saturday afternoon I was riding along a clean flat nature trail; no
sticks in the gears, no nothing. I was going at an even speed of
about 20-25mph in the next-highest gear when all of a sudden I hear a
*SNAP*, then something smashed into the rear spokes, causing an almost
instant stop. I was lucky I wasn't going downhill when this occurred,
or I would've flown over the handlebars.

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue. The shifter mechanism
ripped off the aluminum frame, got caught in the rear spokes, and
destroyed the entire rear end of the bike. Several spokes are broken
and/or bent. The shifter mechanism is bent in several places, the
shifter wire is shredded, and the front crank apparatus also has some
damage due to the sudden awkward pull on the chain.

I was not happy. I had to walk 8 miles home while contending with a
pair of minor stress fractures in the legs (I was biking because I
can't run for the moment). I've contacted the dealer but so far no
reply. This $420 bike is just barely over 2 years old, with less than
500 miles on it. I expected to get more than a dollar per mile for
this bike, and I'm really not happy with Trek's poor design of this
frame and model.

If the dealer or Trek will support the repair of this obvious
manufacturer's defect, I will keep you apprised.

Dan


Thank God it wasn't a Bianchi.

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rec.bicycles.off-road is moderated by volunteers. To find help solving
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  #5  
Old March 29th 05, 06:36 PM
external usenet poster
 
Posts: n/a
Default

Dan wrote:
Hi,

Because this is a hybrid I'm not sure whether to place it in racing

or
off-road. But here goes my story.

Saturday afternoon I was riding along a clean flat nature trail; no
sticks in the gears, no nothing. I was going at an even speed of
about 20-25mph in the next-highest gear when all of a sudden I hear a
*SNAP*, then something smashed into the rear spokes, causing an

almost
instant stop. I was lucky I wasn't going downhill when this

occurred,
or I would've flown over the handlebars.

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue. The shifter mechanism
ripped off the aluminum frame, got caught in the rear spokes, and
destroyed the entire rear end of the bike. Several spokes are broken
and/or bent. The shifter mechanism is bent in several places, the
shifter wire is shredded, and the front crank apparatus also has some
damage due to the sudden awkward pull on the chain.

I was not happy. I had to walk 8 miles home while contending with a
pair of minor stress fractures in the legs (I was biking because I
can't run for the moment). I've contacted the dealer but so far no
reply. This $420 bike is just barely over 2 years old, with less

than
500 miles on it. I expected to get more than a dollar per mile for
this bike, and I'm really not happy with Trek's poor design of this
frame and model.

If the dealer or Trek will support the repair of this obvious
manufacturer's defect, I will keep you apprised.

Dan

--
rec.bicycles.off-road is moderated by volunteers. To find help

solving
posting problems, or contact the moderators, please see

http://rbor.org/
Please read the charter before posting:

http://rbor.org/rbor_charter.txt

Your bike sounds like a prime candidate to become a singlespeed.

/s

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  #6  
Old March 30th 05, 02:14 PM
Phil, Squid-in-Training
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Posts: n/a
Default

wrote:
Dan wrote:
Hi,

Because this is a hybrid I'm not sure whether to place it in racing
or off-road. But here goes my story.

Saturday afternoon I was riding along a clean flat nature trail; no
sticks in the gears, no nothing. I was going at an even speed of
about 20-25mph in the next-highest gear when all of a sudden I hear a
*SNAP*, then something smashed into the rear spokes, causing an
almost instant stop. I was lucky I wasn't going downhill when this
occurred, or I would've flown over the handlebars.

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue. The shifter mechanism
ripped off the aluminum frame, got caught in the rear spokes, and
destroyed the entire rear end of the bike. Several spokes are broken
and/or bent. The shifter mechanism is bent in several places, the
shifter wire is shredded, and the front crank apparatus also has some
damage due to the sudden awkward pull on the chain.

I was not happy. I had to walk 8 miles home while contending with a
pair of minor stress fractures in the legs (I was biking because I
can't run for the moment). I've contacted the dealer but so far no
reply. This $420 bike is just barely over 2 years old, with less
than 500 miles on it. I expected to get more than a dollar per mile
for this bike, and I'm really not happy with Trek's poor design of
this frame and model.

If the dealer or Trek will support the repair of this obvious
manufacturer's defect, I will keep you apprised.

Dan

--
rec.bicycles.off-road is moderated by volunteers. To find help
solving posting problems, or contact the moderators, please see
http://rbor.org/ Please read the charter before posting:
http://rbor.org/rbor_charter.txt

Your bike sounds like a prime candidate to become a singlespeed.


LOL nice way to look at it...

--
Phil, Squid-in-Training


--
rec.bicycles.off-road is moderated by volunteers. To find help solving
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  #7  
Old March 30th 05, 07:25 PM
Werehatrack
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On Wed, 30 Mar 2005 07:14:36 CST, "Phil, Squid-in-Training"
may have said:

wrote:
Your bike sounds like a prime candidate to become a singlespeed.


LOL nice way to look at it...


If half the right dropout is gone, it's not much of a candidate for
conversion until the dropout has been replaced. (Not to mention the
possible bent stays.)

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

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  #8  
Old March 30th 05, 09:35 PM
David L. Johnson
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On Sun, 27 Mar 2005 21:16:11 -0600, Dan wrote:

Hi,

Because this is a hybrid I'm not sure whether to place it in racing or
off-road. But here goes my story.


*.racing trimmed off as irrelevant.

Saturday afternoon I was riding along a clean flat nature trail; no
sticks in the gears, no nothing. I was going at an even speed of
about 20-25mph in the next-highest gear when all of a sudden I hear a
*SNAP*, then something smashed into the rear spokes, causing an almost
instant stop. I was lucky I wasn't going downhill when this occurred,
or I would've flown over the handlebars.

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue.


How do you figure this was due to metal fatigue? I assume that this small
piece of aluminum is the derailleur hanger, which is not subject to a lot
of stress under normal use. In order to claim some sort of fault of the
manufacturer, you have to be able to convince them that this was the cause
of the problem. The rest of the damage was collateral.

In my experience, derailleurs usually snap off either because the chain
dropped and got tangled in the pulleys, which then twisted the derailleur
off since you were still applying pressure to the pedals, or there was a
missed shift under load, causing essentially the same chain of events. I
have seen both of these occur, one on the flat, and the other (the
missed-shift then crunch) on a short, steep climb. One other possibility
that can occur is if you shift it into the spokes, which is caused by a
misadjusted derailleur. However, I don't imagine this was the cause due
to the circumstances you describe.

Are you _sure_ you hadn't shifted at that point, or had the chain fall off
the chainring? I know it's easy for the dealer to just say it was
operator error and not take responsibility, but you need an explanation
why this was not the case here.


If the dealer or Trek will support the repair of this obvious
manufacturer's defect, I will keep you apprised.


Don't be surprised if the obviousness of the defect is missed by the
dealer. I don't see it, and would have to be convinced.

--

David L. Johnson

__o | A mathematician is a machine for turning coffee into theorems.
_`\(,_ | -- Paul Erdos
(_)/ (_) |


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  #9  
Old March 31st 05, 04:18 AM
Keith Rickert
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Default

In article ,
"David L. Johnson" wrote:

On Sun, 27 Mar 2005 21:16:11 -0600, Dan wrote:

Hi,

Because this is a hybrid I'm not sure whether to place it in racing or
off-road. But here goes my story.


*.racing trimmed off as irrelevant.

Saturday afternoon I was riding along a clean flat nature trail; no
sticks in the gears, no nothing. I was going at an even speed of
about 20-25mph in the next-highest gear when all of a sudden I hear a
*SNAP*, then something smashed into the rear spokes, causing an almost
instant stop. I was lucky I wasn't going downhill when this occurred,
or I would've flown over the handlebars.

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue.


How do you figure this was due to metal fatigue? I assume that this small
piece of aluminum is the derailleur hanger, which is not subject to a lot
of stress under normal use. In order to claim some sort of fault of the
manufacturer, you have to be able to convince them that this was the cause
of the problem. The rest of the damage was collateral.

In my experience, derailleurs usually snap off either because the chain
dropped and got tangled in the pulleys, which then twisted the derailleur
off since you were still applying pressure to the pedals, or there was a
missed shift under load, causing essentially the same chain of events. I
have seen both of these occur, one on the flat, and the other (the
missed-shift then crunch) on a short, steep climb. One other possibility
that can occur is if you shift it into the spokes, which is caused by a
misadjusted derailleur. However, I don't imagine this was the cause due
to the circumstances you describe.


The other cause that I've seen has been either picking up a stick
(mountain biking) or (happened to me) wheel reflector comes partly
loose, twists sideways, and takes out the derailleur along the way.

Keith

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  #10  
Old April 1st 05, 02:25 PM
[email protected]
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Dan wrote:

snip

It turns out that a small piece of the aluminum frame supporting the
gear shifter wore out due to metal fatigue. The shifter mechanism
ripped off the aluminum frame, got caught in the rear spokes, and
destroyed the entire rear end of the bike. Several spokes are broken
and/or bent. The shifter mechanism is bent in several places, the
shifter wire is shredded, and the front crank apparatus also has some
damage due to the sudden awkward pull on the chain.


I would be willing to bet that the manufacturer finds an excuse to not
do anything, even if the dealer goes to bat for you. It doesn't matter
what the actual cause of the failure was, it's whether or not they can
find a way to not do anything, since it's your word against their's.
There could be several reasons why the hanger was stressed, i.e. the
chain could have fallen off and gotten stuck, while you tried to pedal
harder because you didn't realize what happened. If they do do
something for you, it both admits liability, and it implies that there
is a problem with the product, neither of which is worth keeping you as
a customer.

You really want to avoid aluminum frames if at all possible, but you're
not going to find many $420 bicycles with chromoloy steel frames! Metal
fatigue is a huge problem with aluminum, and not just on bicycles. Of
course most of the time you'll be just fine, but it's those
catastrophic failures, that are much more likely to occur with
aluminum, that are scary. The derailleur hanger can be subjected to a
lot of stress, with not a lot of metal there.

--------------Begin Obligatory Airplane Comparison---------------
"When discussing aluminum, someone always brings up airplanes. Airplane
design showcases what aluminum does best: acceptable strength and a low
relative weight. But, aluminum's lack of a fatigue limit is one very
good reason why there is stringent monitoring of dynamically or
cyclically stressed aluminum structures."
----------------End Obligatory Airplane Comparison---------------

You can see what happens when aluminum fails on an aircraft
"http://the.honoluluadvertiser.com/2001/Jan/18/118localnews1.html"

There are still some chromoloy frame mountain bikes available. Slap on
some slicks, and call it a hybrid. Marin still makes several steel
mountain bikes that are not excessively expensive (but more than $420).
See
"http://marinbikes.com/bicycles_2005/html/bikes/bike_series/bikes_ser_steelht.html"
The Bear Valley is $650 MSRP, though REI still has some (or one) 17"
2004 Bear Valley's on sale for $390 (see
"http://www.rei.com/outlet/product/47943588.htm?vcat=OUTLET_SSHP_CYCLING_SA").

I don't think that there are any chromolloy steel hybrids available
anymore; hybrids tend to be relatively inexpensive, and aluminum is a
lot less expensive than chromoly steel.

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