Fixing loose pedal

02-20-2005, 10:43 AM

The left pedal of my bike has recently come loose to the point that it
falls off after a few seconds of attempted riding. I tried to stick it
back on with super glue, but this didn't work. Any ideas?

02-20-2005, 11:18 AM

<[Only registered and activated users can see links. ]> wrote: (clip)super glue (clip) didn't work. Any
ideas?
^^^^^^^^^^^^^^
It's likely that over time, you may have been riding with a loose pedal,
which would cause the threads to wear. Now, when you tighten it, the thread
still has clearance, and can wiggle. Super glue is fairly brittle, so it
probably breaks up when you start to ride. As an alternative, I suggest you
try Lock-tite. There are different grades for different applications, but
they are all more tenacious and pliable than C/A glue.

02-20-2005, 11:18 AM

<[Only registered and activated users can see links. ]> wrote: (clip)super glue (clip) didn't work. Any
ideas?
^^^^^^^^^^^^^^
It's likely that over time, you may have been riding with a loose pedal,
which would cause the threads to wear. Now, when you tighten it, the thread
still has clearance, and can wiggle. Super glue is fairly brittle, so it
probably breaks up when you start to ride. As an alternative, I suggest you
try Lock-tite. There are different grades for different applications, but
they are all more tenacious and pliable than C/A glue.

02-20-2005, 12:29 PM

Leo Lichtman writes:

> It's likely that over time, you may have been riding with a loose
> pedal, which would cause the threads to wear. Now, when you tighten
> it, the thread still has clearance, and can wiggle. Super glue is
> fairly brittle, so it probably breaks up when you start to ride. As
> an alternative, I suggest you try Loctite. There are different
> grades for different applications, but they are all more tenacious
> and pliable than C/A glue.

[Only registered and activated users can see links. ]

I think that is a reasonable assessment and because pedals naturally
move in crank threads even when in best condition. A pedal ridden
until it falls out has probably ruined the threads to the point that
there is no practical repair possible.

No means other than a new crank can secure this interface now. The
reason for left hand threads on left cranks is that the pedal spindle
is always moving, no matter how much it is tightened and in that mode,
it will unscrew from precession without a left hand thread (or a right
hand thread for right cranks).

This design problem deserves to be fixed because thread motion also
causes crank failures in which the pedal suddenly breaks out of the
crank throwing the rider to the ground if standing at that moment.
When the left crank does this, the rider falls under any adjacent
vehicle (in right hand traffic). This is a design flaw that can be
fixed easily but because bicycles have always had this problem, no one
wants to fix it.

I have implemented the fix and I have tested it over a period during
which I would most likely have had five or so crank failures, judging
from failure rates prior to the design change. The change was made on
cranks identical to ones that previously failed and from the same
production of which I had reserves because they failed so often.

Jobst Brandt
[Only registered and activated users can see links. ]

02-20-2005, 12:29 PM

Leo Lichtman writes:

> It's likely that over time, you may have been riding with a loose
> pedal, which would cause the threads to wear. Now, when you tighten
> it, the thread still has clearance, and can wiggle. Super glue is
> fairly brittle, so it probably breaks up when you start to ride. As
> an alternative, I suggest you try Loctite. There are different
> grades for different applications, but they are all more tenacious
> and pliable than C/A glue.

[Only registered and activated users can see links. ]

I think that is a reasonable assessment and because pedals naturally
move in crank threads even when in best condition. A pedal ridden
until it falls out has probably ruined the threads to the point that
there is no practical repair possible.

No means other than a new crank can secure this interface now. The
reason for left hand threads on left cranks is that the pedal spindle
is always moving, no matter how much it is tightened and in that mode,
it will unscrew from precession without a left hand thread (or a right
hand thread for right cranks).

This design problem deserves to be fixed because thread motion also
causes crank failures in which the pedal suddenly breaks out of the
crank throwing the rider to the ground if standing at that moment.
When the left crank does this, the rider falls under any adjacent
vehicle (in right hand traffic). This is a design flaw that can be
fixed easily but because bicycles have always had this problem, no one
wants to fix it.

I have implemented the fix and I have tested it over a period during
which I would most likely have had five or so crank failures, judging
from failure rates prior to the design change. The change was made on
cranks identical to ones that previously failed and from the same
production of which I had reserves because they failed so often.

Jobst Brandt
[Only registered and activated users can see links. ]

02-20-2005, 02:19 PM

<[Only registered and activated users can see links. ]> wrote in message
news:rj7Sd.7651$[Only registered and activated users can see links. ]...
> Leo Lichtman writes:
>
>> It's likely that over time, you may have been riding with a loose
>> pedal, which would cause the threads to wear. Now, when you tighten
>> it, the thread still has clearance, and can wiggle. Super glue is
>> fairly brittle, so it probably breaks up when you start to ride. As
>> an alternative, I suggest you try Loctite. There are different
>> grades for different applications, but they are all more tenacious
>> and pliable than C/A glue.
>
> [Only registered and activated users can see links. ]
>
> I think that is a reasonable assessment and because pedals naturally
> move in crank threads even when in best condition. A pedal ridden
> until it falls out has probably ruined the threads to the point that
> there is no practical repair possible.
>
> No means other than a new crank can secure this interface now. The
> reason for left hand threads on left cranks is that the pedal spindle
> is always moving, no matter how much it is tightened and in that mode,
> it will unscrew from precession without a left hand thread (or a right
> hand thread for right cranks).
>
> This design problem deserves to be fixed because thread motion also
> causes crank failures in which the pedal suddenly breaks out of the
> crank throwing the rider to the ground if standing at that moment.
> When the left crank does this, the rider falls under any adjacent
> vehicle (in right hand traffic). This is a design flaw that can be
> fixed easily but because bicycles have always had this problem, no one
> wants to fix it.
>
> I have implemented the fix and I have tested it over a period during
> which I would most likely have had five or so crank failures, judging
> from failure rates prior to the design change. The change was made on
> cranks identical to ones that previously failed and from the same
> production of which I had reserves because they failed so often.
>
> Jobst Brandt
> [Only registered and activated users can see links. ]

Another thing that may work OK is to clean the pedal threads and the crank
arm threads thoroughly.
Then use JB Weld epoxy or an equivalent metalized epoxy adhesive to glue the
pedal back in.
Another way is to clean the crank arm threads after you remove it from the
bike, and using a Propane torch, heat it up real good
and use a good quality aluminum soldering rod or two or three to fill in the
hole, then drill and retap the hole with the appropriate left or right hand
tap.
Most bikes use 9/16x20 threads, but the cheaper bikes with 1 peice cranks
typically use 1/2"x20' threads left or right hand.
But I suppose if you are careful, you could do this without removing the
crank arm, but drilling and tapping a straight hole may be difficult.

02-20-2005, 02:19 PM

<[Only registered and activated users can see links. ]> wrote in message
news:rj7Sd.7651$[Only registered and activated users can see links. ]...
> Leo Lichtman writes:
>
>> It's likely that over time, you may have been riding with a loose
>> pedal, which would cause the threads to wear. Now, when you tighten
>> it, the thread still has clearance, and can wiggle. Super glue is
>> fairly brittle, so it probably breaks up when you start to ride. As
>> an alternative, I suggest you try Loctite. There are different
>> grades for different applications, but they are all more tenacious
>> and pliable than C/A glue.
>
> [Only registered and activated users can see links. ]
>
> I think that is a reasonable assessment and because pedals naturally
> move in crank threads even when in best condition. A pedal ridden
> until it falls out has probably ruined the threads to the point that
> there is no practical repair possible.
>
> No means other than a new crank can secure this interface now. The
> reason for left hand threads on left cranks is that the pedal spindle
> is always moving, no matter how much it is tightened and in that mode,
> it will unscrew from precession without a left hand thread (or a right
> hand thread for right cranks).
>
> This design problem deserves to be fixed because thread motion also
> causes crank failures in which the pedal suddenly breaks out of the
> crank throwing the rider to the ground if standing at that moment.
> When the left crank does this, the rider falls under any adjacent
> vehicle (in right hand traffic). This is a design flaw that can be
> fixed easily but because bicycles have always had this problem, no one
> wants to fix it.
>
> I have implemented the fix and I have tested it over a period during
> which I would most likely have had five or so crank failures, judging
> from failure rates prior to the design change. The change was made on
> cranks identical to ones that previously failed and from the same
> production of which I had reserves because they failed so often.
>
> Jobst Brandt
> [Only registered and activated users can see links. ]

Another thing that may work OK is to clean the pedal threads and the crank
arm threads thoroughly.
Then use JB Weld epoxy or an equivalent metalized epoxy adhesive to glue the
pedal back in.
Another way is to clean the crank arm threads after you remove it from the
bike, and using a Propane torch, heat it up real good
and use a good quality aluminum soldering rod or two or three to fill in the
hole, then drill and retap the hole with the appropriate left or right hand
tap.
Most bikes use 9/16x20 threads, but the cheaper bikes with 1 peice cranks
typically use 1/2"x20' threads left or right hand.
But I suppose if you are careful, you could do this without removing the
crank arm, but drilling and tapping a straight hole may be difficult.

02-20-2005, 02:29 PM

"Earl Bollinger" wrote: (clip) But I suppose if you are careful, you could
do this without removing the crank arm, but drilling and tapping a straight
hole may be difficult.
^^^^^^^^^^^^^^
I would say, "Next to impossible." The threaded hole has to be parallel to
the bottom bracket axis, which is not easily to get by eye. It almost HAS
to be done on a drill press or mill, with proper measuring and clamping. If
the angle is off, you will feel the pedal "orbiting" on every revolution.

02-20-2005, 02:29 PM

"Earl Bollinger" wrote: (clip) But I suppose if you are careful, you could
do this without removing the crank arm, but drilling and tapping a straight
hole may be difficult.
^^^^^^^^^^^^^^
I would say, "Next to impossible." The threaded hole has to be parallel to
the bottom bracket axis, which is not easily to get by eye. It almost HAS
to be done on a drill press or mill, with proper measuring and clamping. If
the angle is off, you will feel the pedal "orbiting" on every revolution.

02-20-2005, 03:07 PM

On 2005-02-20, [Only registered and activated users can see links. ] <[Only registered and activated users can see links. ]> wrote:

> The left pedal of my bike has recently come loose to the point that it
> falls off after a few seconds of attempted riding. I tried to stick it
> back on with super glue, but this didn't work. Any ideas?

It sounds like your crank arm threads are ruined, probably fromn riding
with a loose pedal. Short of buying a new crank arm, the only thing you
can do is find a bike shop with the ELDI pedal bushing system. This works
by reaming out and retapping the arm to accommodate a threaded bushing,
which in turn will allow you to reinstall your pedal. These used to be
fairly common, but I haven't seen them for a while now.

--

John ([Only registered and activated users can see links. ].org)