help: i break rear freehub bodies regularly...

All,

I'm a hobbyist mountain biker (road too). I weigh 250# and am 6'4", with strong legs.

I regularly break the freehub bodies when I ride in Moab Utah on the slickrock surfaces there.
(I go once a year for vacation.) I generally break them while climbing the short 20-30% grades
in a low gear.

Each of the past two years I've broken the freehub body on two consecutive days (thankfully Poison
Spider bike shop warrantied the part both times). The freehubs I've broken are Shimano XT/LX/other.

My current count is 8 freehub bodies in the past 5 years.

I'm tired of breaking them and am looking for another solution.

Phil Wood gets high praise, but they do have the same basic design (pawls) - and that's a bit
worrisome. Chris King has their RingDrive(tm) - which sounds cool, but nobody else has that design
and I worry about that.

I generally ride single track and dirt roads, with the annual trip to Moab. No big drops for me,
just lots of climbing.

Any help?

thanks,

BFW

 

"bigfaceworm" <[email protected]> wrote in message
news:[email protected]...

> I weigh 250# and am 6'4", with strong legs. I regularly break the freehub bodies The freehubs I've
> broken are Shimano XT/LX/other. I'm tired of breaking them and am looking for another solution.

> Chris King has their RingDrive(tm) - which sounds cool, but nobody else has that design and I
> worry about that.

Call Chris King and tell them your story: The King hub is probably your answer; but let them tell
you if a King hub is for you or not. They're reputed to be bombproof; but most people don't destroy
freehubs like you do, so maybe they're not made for that kind of abuse.

Another possibility is a Shimano Silent Clutch hub. It uses a centrifugal clutch instead of pawls.
Might be stronger - might not be. I just know it's different from the other Shimano freehubs.

Wish I had a definite answer for you; but I suggest that you call the manufacturers and try to talk
with an engineer or at least a knowledgeable product rep. Surely you're not the first guy who has
destroyed freehub bodies with such frequency.

BTW: Ever thought about racing?

Best of luck,

Barry

 

"bigfaceworm" <[email protected]> wrote in message
news:[email protected]...
> I regularly break the freehub bodies when I ride in Moab Utah on the slickrock surfaces there. (I
> go once a year for vacation.) I generally break them while climbing the short 20-30% grades in a
> low gear.

What part of the assembly, specifically, are you breaking?

--
==================
Kraig Willett www.biketechreview.com
==================

 

"Kraig Willett" <[email protected]> wrote in message
news:<[email protected]>...
> What part of the assembly, specifically, are you breaking?

I believe I am breaking the pawls, though I've always let the shop do the work and not examined the
part myself.

They symptoms are:
- loud snap sound when it happens
- the inability to glide - i must continuously pedal or the chain will wind up.
- inability to pedal hard - pedalling hard results in more noise and the pedals just spinning (the
back wheel doesn't rotate)

 

"bigfaceworm" <[email protected]> wrote in message
news:[email protected]...
> "Kraig Willett" <[email protected]> wrote in message
news:<[email protected]>...
> > What part of the assembly, specifically, are you breaking?
>
> I believe I am breaking the pawls, though I've always let the shop do the work and not examined
> the part myself.
>
> They symptoms are:
> - loud snap sound when it happens
> - the inability to glide - i must continuously pedal or the chain will wind up.
> - inability to pedal hard - pedalling hard results in more noise and the pedals just spinning (the
> back wheel doesn't rotate)

Your failures puzzle me a bit. I have laboratory tested wheels that use the LX hub at around 2500 -
3000 in-lb of torque (extremely large) and that produced a failure of the aluminum spline on the
hubshell itself (IIRC, after 10,000 cycles or so) - the freehub did not fail.

I have also longitudinally cracked other shimano steel freehub shells using very similar test
protocols. Of the 30 or so wheels that I tested, I didn't observe a pawl failure. This is why I am a
bit puzzled.

Anybody else produce shimano pawl failures?

--
==================
Kraig Willett www.biketechreview.com
==================

 

> > "Kraig Willett" <[email protected]> wrote in message
> news:<[email protected]>...
> > > What part of the assembly, specifically, are you breaking?

> "bigfaceworm" <[email protected]> wrote in message
> news:[email protected]...
> > I believe I am breaking the pawls, though I've always let the shop do the work and not examined
> > the part myself.
> >
> > They symptoms are:
> > - loud snap sound when it happens
> > - the inability to glide - i must continuously pedal or the chain will wind up.
> > - inability to pedal hard - pedalling hard results in more noise and the pedals just spinning
> > (the back wheel doesn't rotate)

"Kraig Willett" <[email protected]> wrote in message
news:[email protected]...
> Your failures puzzle me a bit. I have laboratory tested wheels that use
the
> LX hub at around 2500 - 3000 in-lb of torque (extremely large) and that produced a failure of
> the aluminum spline on the hubshell itself (IIRC, after 10,000 cycles or so) - the freehub did
> not fail.
>
> I have also longitudinally cracked other shimano steel freehub shells
using
> very similar test protocols. Of the 30 or so wheels that I tested, I
didn't
> observe a pawl failure. This is why I am a bit puzzled.
>
> Anybody else produce shimano pawl failures?

Yes. We see them but not in any consistent pattern. Large riders with daily commute climbs and small
riders in infrequent use. The failure is normally a broken pawl, not the outer case of the cassette
body. And this is not an epidemic - ten or a dozen per year out of a lot of service. I haven't lost
one on one of my own bikes but we sell relatively small numbers of midprice Shimano cassette
equipped bicycles.

I agree it sounds astronomically implausible that one rider would find several defective Shimano
cassette bodies in a series. But I can't postulate a scenario that would cause such a repeatable
failure either - they are pretty tough and dependable overall, especially within their price range.
He does accurately describe a pawl failure.
--
Andrew "stumped" Muzi http://www.yellowjersey.org Open every day since 1 April 1971

 

In article <[email protected]>, "A Muzi" <[email protected]> wrote:

>I agree it sounds astronomically implausible that one rider would find several defective Shimano
>cassette bodies in a series.

Maybe if successive cassette bodies were being bought from the same shop, and if that shop was
selling from a batch bought at one time, and if that batch had a manufacturing defect?

--
Ned Mantei Department of Cell Biology, Swiss Federal Institute of Technology CH-8093 Zurich,
Switzerland

 

Ned Mantei <[email protected]> wrote in message
news:<[email protected]>...
> Maybe if successive cassette bodies were being bought from the same shop, and if that shop was
> selling from a batch bought at one time, and if that batch had a manufacturing defect?

Unfortunately, that wasn't the case: In 2003, the first one to break was installed in 2002 (at shop
in Moab) the second was the replacement installed in 2003 (at shop in Moab)

In 2002, the first one to break was on a brand new wheel from Oregon the second was installed at the
shop in Moab

In earlier years they were from a variety of shops...

The shop in Moab says they regularly replace anywhere from 2-4 freehub bodies A DAY! during peak
mountain biking season. And that's just one of the 5(?) shops in Moab.

Oddly, my brother (same weight, same riding style) has been using the same wheel (and freehub body)
for 5 years now, riding the same rides. No breakage...

I have changed the freehub shell two times, so I didn't think it was the problem. But perhaps
there's some problem with the shell and the way it interacts with the pawls...

 

Ned Mantei <[email protected]> wrote:

>In article <[email protected]>, "A Muzi" <[email protected]> wrote:
>
>>I agree it sounds astronomically implausible that one rider would find several defective Shimano
>>cassette bodies in a series.
>
>Maybe if successive cassette bodies were being bought from the same shop, and if that shop was
>selling from a batch bought at one time, and if that batch had a manufacturing defect?

My guess is that the rider with all the failures is somehow injecting grease into the freehub to
lube it. This will prevent the pawls from fully seating , so it's not that difficult to damage them
one at a time until they all fail catastrophically.

Either that or he's insanely strong, immensely heavy, or supremely unlucky. ;-)

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame

 

how about the gearing? 250 lbs. on something like 22/32 is allot of torque just an idea

 

"A Muzi" <[email protected]> wrote...
> I agree it sounds astronomically implausible that one rider would find several defective Shimano
> cassette bodies in a series. But I can't postulate a scenario that would cause such a repeatable
> failure either - they are pretty tough and dependable overall, especially within their price
> range. He does accurately describe a pawl failure.

I used to break freehubs at the pawls pretty often (a few times a year) and still break one every
year or so. I think the mechanism is that you start with a partial engagement which slips and leads
to the pawls slamming into the next engagement point really hard and failing.

I ride a lot in the winter (thickens up the lube so the pawls don't engage as quickly or completely)
and do a lot of trials stuff (sudden pedal kicks when the hub isn't really engaged) and I think that
leads to my problems. I've gotten better at being smoother and making sure the hub is engaged before
pedalling and it helps some.

Trials guys love the Chris King hubs and a lot of them used the LX silent clutch (? do they still
make that) and both of them apparently stand up better than the Shimano hubs to this kind of thing.

- Marty G

 

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Marty Gulaian wrote:

>"A Muzi" <[email protected]> wrote...
>
>
>>I agree it sounds astronomically implausible that one rider would find several defective Shimano
>>cassette bodies in a series. But I can't postulate a scenario that would cause such a repeatable
>>failure either - they are pretty tough and dependable overall, especially within their price
>>range. He does accurately describe a pawl failure.
>>
>>
>
>I used to break freehubs at the pawls pretty often (a few times a year) and still break one every
>year or so. I think the mechanism is that you start with a partial engagement which slips and leads
>to the pawls slamming into the next engagement point really hard and failing.
>
>I ride a lot in the winter (thickens up the lube so the pawls don't engage as quickly or
>completely) and do a lot of trials stuff (sudden pedal kicks when the hub isn't really engaged) and
>I think that leads to my problems. I've gotten better at being smoother and making sure the hub is
>engaged before pedalling and it helps some.
>
>Trials guys love the Chris King hubs and a lot of them used the LX silent clutch (? do they still
>make that) and both of them apparently stand up better than the Shimano hubs to this kind of thing.
>
>- Marty G
>
>
I second that. I had a pawl failure and it was after I'd acquired a dumb habit of pedalling with one
leg, through a very smal arc. The jerky motion resulted in a repeated shock impact on the pawls
rather than a simple load carrying. I didn't think much about it until after the failure. Is there
something about the user's riding style on these trails that results in these kind of "pedal kicks"
and pawl impacts? He claims his brother has the same riding style but perhaps there is a difference
in the smoothness and acceleration of the pedals before the pawl engagement.

--------------090208060808050402010104 Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title></title>
</head> <body> <br> <br> Marty Gulaian wrote:<br> <blockquote type="cite"
cite="[email protected]"> <pre wrap="">"A Muzi" <a
class="moz-txt-link-rfc2396E" href="mailto:[email protected]"><[email protected]></a>
wrote... </pre> <blockquote type="cite"> <pre wrap="">I agree it sounds astronomically implausible
that one rider would find several defective Shimano cassette bodies in a series. But I can't
postulate a scenario that would cause such a repeatable failure either - they are pretty tough and
dependable overall, especially within their price range. He does accurately describe a pawl failure.
</pre> </blockquote> <pre wrap=""><!----> I used to break freehubs at the pawls pretty often (a few
times a year) and still break one every year or so. I think the mechanism is that you start with a
partial engagement which slips and leads to the pawls slamming into the next engagement point really
hard and failing.

I ride a lot in the winter (thickens up the lube so the pawls don't engage as quickly or completely)
and do a lot of trials stuff (sudden pedal kicks when the hub isn't really engaged) and I think that
leads to my problems. I've gotten better at being smoother and making sure the hub is engaged before
pedalling and it helps some.

Trials guys love the Chris King hubs and a lot of them used the LX silent clutch (? do they still
make that) and both of them apparently stand up better than the Shimano hubs to this kind of thing.

- Marty G </pre> </blockquote> I second that. I had a pawl failure and it was after I'd
acquired a dumb habit of pedalling with one leg, through a very smal arc. The jerky motion
resulted in a repeated shock impact on the pawls rather than a simple load carrying. I
didn't think much about it until after the failure. Is there something about the user's
riding style on these trails that results in these kind of "pedal kicks" and pawl impacts?
He claims his brother has the same riding style but perhaps there is a difference in the
smoothness and acceleration of the pedals before the pawl engagement.<br> </body> </html>

--------------090208060808050402010104--

 

John Albergo <[email protected]> wrote in message news:<[email protected]>...
> I second that. I had a pawl failure and it was after I'd acquired a dumb habit of pedalling with
> one leg, through a very smal arc. The jerky motion resulted in a repeated shock impact on the
> pawls rather than a simple load carrying. I didn't think much about it until after the failure. Is
> there something about the user's riding style on these trails that results in these kind of "pedal
> kicks" and pawl impacts? He claims his brother has the same riding style but perhaps there is a
> difference in the smoothness and acceleration of the pedals before the pawl engagement.

I'd like to think my pedaling is somewhat smooth, but...

I'm definitely not slamming down on the pedal suddenly. If memory serves me right, the breaks
generally happen in the middle (well end) of the short & steep climbs. So, the hub should already be
engaged. But I probably pedal more piston- like than a smooth circle.

Someone commented on my injecting grease that might foul up the pawl action. I would hope that the
bike shops installed the hubs w/the correct amount of lubrication. I can say that I personally
didn't inject any grease b/c I'm kind of lazy about hub maintenance.

I don't remember the gearing ratio - it's a pretty standard triple ring up front and 9 speed in the
back. Lots of torque.

Lastly, I've broken the Shimano silent hub mechanism also. In that case, the shop was unable to
extract the freehub body and had to replace the whole thing (I got a new wheel).

 

[email protected] (bigfaceworm) wrote:

>I'd like to think my pedaling is somewhat smooth, but...
>
>I'm definitely not slamming down on the pedal suddenly. If memory serves me right, the breaks
>generally happen in the middle (well end) of the short & steep climbs. So, the hub should already
>be engaged. But I probably pedal more piston- like than a smooth circle.

I've seen people with such choppy spins that they actually "freewheel" for a split second with the
pedals at 12 and 6 o'clock. If so, the pawls would have to re-engage twice every crank revolution..
effectively putting the rear hub through an accelerated life testing process (getting the equivalent
of many years of "normal riding" during a few steep hills).

>Someone commented on my injecting grease that might foul up the pawl action. I would hope that the
>bike shops installed the hubs w/the correct amount of lubrication. I can say that I personally
>didn't inject any grease b/c I'm kind of lazy about hub maintenance.

That was my suggestion - lots o' folks have messed up their pawls with grease, but it doesn't sound
like your problem now.

>I don't remember the gearing ratio - it's a pretty standard triple ring up front and 9 speed in the
>back. Lots of torque.
>
>Lastly, I've broken the Shimano silent hub mechanism also. In that case, the shop was unable to
>extract the freehub body and had to replace the whole thing (I got a new wheel).

Whatever it is you're doing - cut it out!!! ;-)

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame