Rebending steel dropouts

I had my rder shatter a hole in my plastic spoke protector as it went through it enroute to getting trapped in my spokes. Not sure if the freewheel bearings snagged first (I had suspicions the bearings were starting to go) or the axle bent first, but suspect the former. At any rate, the left dropout is bent open (bicycle pitch axis, slightly lateral). It’s a steel framed mountain bike, my low end beater. If I re-bend the dropouts back to original shape, are they likely to be weakened so as to be prone to failure?

 

It depends on how cheap a frame. I wouldn't trust doing
it to a department store frame. I have done it two years ago to a old
late 80s Schwinn and early 90s GT frame with no problems.

 

No, I'd say you're pretty safe. Especially if it is your beater bike. I've rebent plenty of dropouts like that on Wal*Mart bikes in the shop for kids, and they keep on riding them into the ground. Steel is resilient like that. More power to you.

 

On Sun, 16 Jan 2005 20:58:07 +1100, meb
<[email protected]> may have said:

>
>I had my rder shatter a hole in my plastic spoke protector as it went
>through it enroute to getting trapped in my spokes. Not sure if the
>freewheel bearings snagged first (I had suspicions the bearings were
>starting to go) or the axle bent first, but suspect the former.

It's a possibility, but check the der for a sticky pivot before you
ride it again. That's just one of several things that can put the
cage into the spokes.

> At any
>rate, the left dropout is bent open (bicycle pitch axis, slightly
>lateral). It’s a steel framed mountain bike, my low end beater. If I
>re-bend the dropouts back to original shape, are they likely to be
>weakened so as to be prone to failure?

The back end of the dropout is not the part that carries most of the
riding stress; as long as it doesn't develop cracks when you bend it
back, I wouldn't worry about it. Cheap beater frames tend to be more
forgiving about this than fancy bikes, in my experience.

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meb wrote:

> I had my rder shatter a hole in my plastic spoke protector as it went
> through it enroute to getting trapped in my spokes. Not sure if the
> freewheel bearings snagged first (I had suspicions the bearings were
> starting to go) or the axle bent first, but suspect the former. At any
> rate, the left dropout is bent open (bicycle pitch axis, slightly
> lateral). It’s a steel framed mountain bike, my low end beater. If I
> re-bend the dropouts back to original shape, are they likely to be
> weakened so as to be prone to failure?

Yes, but what have you got to lose?

I generally do this sort of repair with a monkey wrench (right-angle
adjustable wrench) and an Inertial Impact Alignment Instrument (hammer.)

Use the monkey wrench to help bring the bottom of the dropout into the
correct plane while simultaneously hammering it back so that the axle
slot becomes parallel.

Cheapo bikes these days often come with horrible axle nuts and no
washers between the nuts and the dropout. This is bad news in general,
and should never be used on a dropout that has been bent open then
closed up again.

As the nut turns while pressing against the dropout it is very liable to
force it open.

If possible, buy a pair of proper track nuts with captive washers. If
not, buy a pair of "serrated axle washers" to fit between the nuts and
the dropouts, or convert to quick release.

Sheldon "Nuts" Brown
+------------------------------------+
| Immigrants are not our burden, |
| They are our wealth --Jane Adams |
+------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

On Sun, 16 Jan 2005 12:07:59 -0500, Sheldon Brown
<[email protected]> may have said:

>Cheapo bikes these days often come with horrible axle nuts and no
>washers between the nuts and the dropout.

I suspect that you may be referring to the ones with the lovely
serrated flanges that are unsurpassed in their ability to tear up the
surface of the dropout. (I've seen some even less useful nuts used as
well, though, such as the ones with a waffled face on the end of the
hex.)

>This is bad news in general,
>and should never be used on a dropout that has been bent open then
>closed up again.
>
>As the nut turns while pressing against the dropout it is very liable to
>force it open.

Teeth grab, transferring torque as lateral force shoving the dropout
open, yup, BTDT, even on a dropout that had not previously been fouled
as far as I could tell. It was on a bike that Huffy would have called
"crude".

>If possible, buy a pair of proper track nuts with captive washers. If
>not, buy a pair of "serrated axle washers" to fit between the nuts and
>the dropouts,

I recall that a discussion of track nuts earlier in the week produced
the information that loose-flange nuts with a 24tpi threading were not
to be had. If that's 3/8-24, I will note that a dig through my Olde
Hardware Boxe turned up exactly one such bit; I don't have a clue what
it was originally used on, but there it was. (It's amazing what 35
years of mechanical packratting can produce at times.)

In the past, when really annoyed by the perversity of machinery, I
have created such loose-flange nuts by finding a washer that was thick
enough to be useful and cutting a shoulder into the nut to allow it to
center in the bore of the washer. The trick is having a sufficiently
large selection of washers to choose from. Cutting the shoulder is
usually no trouble at all; it can be done on a drill press with a
couple of carefully selected sharp files, among other ways.

>or convert to quick release.

Alas, there is one situation in which even this is not an option; the
aforementioned coaster brake...but you knew that. Coasters are, of
course, not exactly the center of a lot of high-tech development and
intensive boutique design marketing, so it's hardly surprising that
the support for unusual requirements involving them is meager.




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Sheldon "Nuts" Brown wrote:

> ...
> Cheapo bikes these days often come with horrible axle nuts and no
> washers between the nuts and the dropout. This is bad news in general,
> and should never be used on a dropout that has been bent open then
> closed up again.
>
> As the nut turns while pressing against the dropout it is very liable to
> force it open.
>
> If possible, buy a pair of proper track nuts with captive washers. If
> not, buy a pair of "serrated axle washers" to fit between the nuts and
> the dropouts, or convert to quick release....

Sheldon,

Are the nuts SRAM and Shimano supply with their internally geared hubs
acceptable? What about the "BOB Nutz" [1] for use with internally geared
hubs and BOB trailers?

[1] <http://www.bobtrailers.com/accessories/bobnutz.php>.

--
Tom Sherman - Near Rock Island

 

On 2005-01-16, meb <[email protected]> wrote:

> I had my rder shatter a hole in my plastic spoke protector as it went
> through it enroute to getting trapped in my spokes. Not sure if the
> freewheel bearings snagged first (I had suspicions the bearings were
> starting to go) or the axle bent first, but suspect the former. At any
> rate, the left dropout is bent open (bicycle pitch axis, slightly
> lateral). It’s a steel framed mountain bike, my low end beater. If I
> re-bend the dropouts back to original shape, are they likely to be
> weakened so as to be prone to failure?

Most dropouts are forged from mild steel to accommodate just this sort of
thing. The exception would be investment cast dropouts, which may be less
forgiving of rebending.

--

-John ([email protected])

 

John Thompson wrote:

> Most dropouts are forged from mild steel to accommodate just this sort of
> thing. The exception would be investment cast dropouts, which may be less
> forgiving of rebending.

Actually, most dropouts are _stamped_ from sheet metal. Only high-end
bikes have forged or investment-cast dropouts.

Sheldon "Wish It Were So" Brown
+---------------------------------------------+
| Television: |
| A medium. So called because it is |
| neither rare nor well done. |
| --Ernie Kovacs |
+---------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

I wrote:
>>Cheapo bikes these days often come with horrible axle nuts and no
>>washers between the nuts and the dropout.
>
Someone who turns into a headgear storage device when the moon is full
wrote:
>
> I suspect that you may be referring to the ones with the lovely
> serrated flanges that are unsurpassed in their ability to tear up the
> surface of the dropout. (I've seen some even less useful nuts used as
> well, though, such as the ones with a waffled face on the end of the
> hex.)
>
I was not referring exclusively to those, but to _any_ nut used without
a washer.
>
>>If possible, buy a pair of proper track nuts with captive washers. If
>>not, buy a pair of "serrated axle washers" to fit between the nuts and
>>the dropouts,

> In the past, when really annoyed by the perversity of machinery, I
> have created such loose-flange nuts by finding a washer that was thick
> enough to be useful and cutting a shoulder into the nut to allow it to
> center in the bore of the washer. The trick is having a sufficiently
> large selection of washers to choose from. Cutting the shoulder is
> usually no trouble at all; it can be done on a drill press with a
> couple of carefully selected sharp files, among other ways.

This is a LOT of trouble to go to. If you can't get track nuts to fit
your axle, just use serrated axle washers (a standard bicycle part.)

They're just as secure. The only advantage of the track nuts is that
they make wheel installation a wee bit faster, since they stay with the
nuts. With loose washers, you just have to make sure to place the
washers on the outsides of the dropouts.
>
>>or convert to quick release.
>
> Alas, there is one situation in which even this is not an option; the
> aforementioned coaster brake...but you knew that. Coasters are, of
> course, not exactly the center of a lot of high-tech development and
> intensive boutique design marketing, so it's hardly surprising that
> the support for unusual requirements involving them is meager.

Actually, there's no inherent reason you couldn't use a quick release
with a coaster brake, but you'd need to source a hollow axle with the
correct threading. That might not be so easy.

Tom Sherman queried:

> Are the nuts SRAM and Shimano supply with their internally geared hubs
> acceptable? What about the "BOB Nutz" [1] for use with internally
> geared hubs and BOB trailers?

Any of these are fine, as long as appropriate serrated washers are used
with them. If the hubs have serrated surfaces on the cone locknuts, you
can even sometimes get by with flat washers.

What's bad is nuts rotating directly against the dropout.

Sheldon "Not That Difficult" Brown
+------------------------------------+
| Experience is a hard teacher, |
| because she gives the test first, |
| the lesson after. -- Vernon Law |
+------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

John Thompson wrote:
> On 2005-01-16, meb <[email protected]> wrote:
>
>
>>I had my rder shatter a hole in my plastic spoke protector as it went
>>through it enroute to getting trapped in my spokes. Not sure if the
>>freewheel bearings snagged first (I had suspicions the bearings were
>>starting to go) or the axle bent first, but suspect the former. At any
>>rate, the left dropout is bent open (bicycle pitch axis, slightly
>>lateral). It’s a steel framed mountain bike, my low end beater. If I
>>re-bend the dropouts back to original shape, are they likely to be
>>weakened so as to be prone to failure?
>
>
> Most dropouts are forged from mild steel to accommodate just this sort of
> thing. The exception would be investment cast dropouts, which may be less
> forgiving of rebending.
>
just like sheldon says, most dropouts are stamped from sheet and easily
bendable. the quality stuff is investment cast [good] or forged
[better]. both are easily destinguished from stamped. forged should be
able to take more abuse than investment cast [although some cast
dropouts are very good indeed].

 

On Sun, 16 Jan 2005 16:34:32 -0500, Sheldon Brown
<[email protected]> may have said:

>I wrote:
>>>Cheapo bikes these days often come with horrible axle nuts and no
>>>washers between the nuts and the dropout.
>>
>Someone who turns into a headgear storage device when the moon is full
>wrote:
>>
>> In the past, when really annoyed by the perversity of machinery, I
>> have created such loose-flange nuts...
>
>This is a LOT of trouble to go to. If you can't get track nuts to fit
>your axle, just use serrated axle washers (a standard bicycle part.)

That works well if the threaded stub is long enough, but sometimes
I've had to work with a non-replaceable existing stud that presented
only six or seven lands of thread for the nut to begin with; in that
instance, making a stepped nut that would go inside a thick washer
allowed the contact surface to be much larger while still getting
enough of a grip on the stud. The only time I went to this extreme
with a bike was when I was installing a set of old-style rear baskets
(with the thick, heavy supports that went to the axle rather than the
dropout tabs) on a historic 3-speed. The original waffle-washer got
counterbored, and the nut shouldered to match. It wasn't the fastest
solution, but it certainly held up well.

>Actually, there's no inherent reason you couldn't use a quick release
>with a coaster brake, but you'd need to source a hollow axle with the
>correct threading. That might not be so easy.

Ayup.

--
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.

 

meb wrote:
> I had my rder shatter a hole in my plastic spoke protector as it went
> through it enroute to getting trapped in my spokes. Not sure if the
> freewheel bearings snagged first (I had suspicions the bearings were
> starting to go) or the axle bent first, but suspect the former. At any
> rate, the left dropout is bent open (bicycle pitch axis, slightly
> lateral). It’s a steel framed mountain bike, my low end beater. If I
> re-bend the dropouts back to original shape, are they likely to be
> weakened so as to be prone to failure?

For steel frames, the cheaper it is, the more likely it is
to survive unscathed. You can't do this:
http://www.yellowjersey.org/brnn.html

to a premium quality frame - it would fail.
And aluminum is almost certain not to survive such
rebending.

Actually cheap bikes tell some amazing tales:
http://www.yellowjersey.org/photosfromthepast/NIMGAFRK.JPG

which would have been fatal to thinner walled, harder materials.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

On Mon, 17 Jan 2005 18:07:50 GMT, John Thompson
<[email protected]> may have said:

>On 2005-01-17, Werehatrack <[email protected]> wrote:
>
>>Sheldon Brown wrote:
>>>Actually, there's no inherent reason you couldn't use a quick release
>>>with a coaster brake, but you'd need to source a hollow axle with the
>>>correct threading. That might not be so easy.
>>
>> Ayup.
>
>Not to mention the fact that the reaction arm makes the very notion of
>"quick release" superfluous on such a hub...

Shorten up the bolt from a quick-release seat clamp, slot the reaction
arm, and you could QR that spot as well.

Of course, the real question would remain "why?"

--
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.

 

On Mon, 17 Jan 2005 18:48:35 -0600, Werehatrack
<[email protected]> wrote:

>On Mon, 17 Jan 2005 18:07:50 GMT, John Thompson
><[email protected]> may have said:
>
>>On 2005-01-17, Werehatrack <[email protected]> wrote:
>>
>>>Sheldon Brown wrote:
>>>>Actually, there's no inherent reason you couldn't use a quick release
>>>>with a coaster brake, but you'd need to source a hollow axle with the
>>>>correct threading. That might not be so easy.
>>>
>>> Ayup.
>>
>>Not to mention the fact that the reaction arm makes the very notion of
>>"quick release" superfluous on such a hub...
>
>Shorten up the bolt from a quick-release seat clamp, slot the reaction
>arm, and you could QR that spot as well.
>
>Of course, the real question would remain "why?"

Dear Werehatrack,

Well, a slot on the rear swing arm or on the front fork
makes it much easier and faster to remove and reinstall
heavy motorcycle wheels.

Carl Fogel

 

David L. Johnson wrote:
> On Mon, 17 Jan 2005 10:35:08 -0800, jim beam wrote:
>
>
>
>>>There's nothing wrong with cast dropouts, but due to the nature of
>>>investment casting they tend to be difficult to bend and subject to
>>>cracking with bending.
>>>
>>
>>ergo, forged better than cast, which are better than stamped...
>
>
> Aren't the old Campagnolo dropouts used on the best frames of the 60's and
> early 70's investment cast? Or are they forged? I've never had to
> straighten one, but wonder what these are.
>
forged. the high quality investment casting you see today is a
relatively recent phenomenon.

 

>>>There's nothing wrong with cast dropouts, but due to the nature of
>>>investment casting they tend to be difficult to bend and subject to
>>>cracking with bending.

> On Mon, 17 Jan 2005 10:35:08 -0800, jim beam wrote:
>>ergo, forged better than cast, which are better than stamped...

David L. Johnson wrote:
> Aren't the old Campagnolo dropouts used on the best frames of the 60's and
> early 70's investment czast? Or are they forged? I've never had to
> straighten one, but wonder what these are.

The old long Campagnolo 1010 ends with the eye lets were
indeed forged, as were the first models of shorter 1010/B
in the middle seventies. About 1981 or so these changed to
a cast SCM part. Shimano made a similar change. Both
brands showed an increase in failures just behind the
chainstay joint and across the web (both ends).

A short lived trend to massive, socketed cast CrMo steel
frame ends faded in favor of both miniature verticals and
alternate materials.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

>>>There's nothing wrong with cast dropouts, but due to the nature of
>>>investment casting they tend to be difficult to bend and subject to
>>>cracking with bending.

> On Mon, 17 Jan 2005 10:35:08 -0800, jim beam wrote:
>>ergo, forged better than cast, which are better than stamped...

David L. Johnson wrote:
> Aren't the old Campagnolo dropouts used on the best frames of the 60's and
> early 70's investment czast? Or are they forged? I've never had to
> straighten one, but wonder what these are.

The old long Campagnolo 1010 ends with the eye lets were
indeed forged, as were the first models of shorter 1010/B
in the middle seventies. About 1981 or so these changed to
a cast SCM part. Shimano made a similar change. Both
brands showed an increase in failures just behind the
chainstay joint and across the web (both ends).

A short lived trend to massive, socketed cast CrMo steel
frame ends faded in favor of both miniature verticals and
alternate materials.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

On 2005-01-17, David L. Johnson <[email protected]> wrote:

> Aren't the old Campagnolo dropouts used on the best frames of the 60's and
> early 70's investment cast? Or are they forged? I've never had to
> straighten one, but wonder what these are.

Nope, they're forged mild steel.

--

-John (john[email protected])