Crank threads keep stripping

[Jason]

I have this reoccurring nightmare where my crank threads keep stripping. It always happens to the
crank with the chain ring (right side). I've gone through 2 sets of cranks now, and I don't
understand why it keeps happening. Is this normal? I do do a lot of hard pedaling, but me thinks
that cranks and crank threads should be able to take such punishment.

Any suggestions?

Jason

 

[Werehatrack]

On Sun, 19 Oct 2003 04:51:57 GMT, Jason <[email protected]> may have said:

>I have this reoccurring nightmare where my crank threads keep stripping. It always happens to the
>crank with the chain ring (right side). I've gone through 2 sets of cranks now, and I don't
>understand why it keeps happening. Is this normal? I do do a lot of hard pedaling, but me thinks
>that cranks and crank threads should be able to take such punishment.
>
>Any suggestions?

If it's the pedal threads that are stripping, they probably just aren't getting tightened
adequately. It's worth the small investment to get one of the open-end wrenches that are designed
for this purpose.

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[GregR]

On Sun, 19 Oct 2003 04:51:57 GMT, Jason <[email protected]> wrote:

>I have this reoccurring nightmare where my crank threads keep stripping. It always happens to the
>crank with the chain ring (right side). I've gone through 2 sets of cranks now, and I don't
>understand why it keeps happening. Is this normal? I do do a lot of hard pedaling, but me thinks
>that cranks and crank threads should be able to take such punishment.

#1 Pedal is not tight enough.. 2 Maybe something wrong with the threads on the pedal (try different
pedal)

What cranks/pedals are you using?

G

 

[Phil Brown]

>I have this reoccurring nightmare where my crank threads keep stripping.

What do you mean by crank threads? What part is failing? Phil Brown

 

[Jason]

On Sun, 19 Oct 2003 16:00:27 +0000, Phil Brown wrote:

>
>>I have this reoccurring nightmare where my crank threads keep stripping.
>
> What do you mean by crank threads? What part is failing? Phil Brown

It is the crank pedal threads that have been stripped. ie: The hole in which the pedal is screwed
into. The pedal threads are fine, but only the right crank gets stripped. This has happened on 2
sets of cranks.

I also noticed that after the first time it happened; the right pedal spun crunchy. I had fixed the
crunchy pedal spin before reinstalling on the second set. I have VP-550 pedals and Both Shimano and
Sakae cranks.

This is getting expensive.

Jason

 

[S. Anderson]

"Jason" <[email protected]> wrote in message news[email protected]...
> It is the crank pedal threads that have been stripped. ie: The hole in which the pedal is screwed
> into. The pedal threads are fine, but only the right crank gets stripped. This has happened on 2
> sets of cranks.
>
> I also noticed that after the first time it happened; the right pedal spun crunchy. I had fixed
> the crunchy pedal spin before reinstalling on the second set. I have VP-550 pedals and Both
> Shimano and Sakae cranks.
>
> This is getting expensive.
>
> Jason

The crank always strips first, since it's aluminum. I have never seen a pedal strip out on a
correctly (read that as "tightly") installed pedal. Are you using sufficient leverage to tighten the
pedal? It should be quite tight. If you are using a regular length 15mm spanner you would have to
tighten it as much as you could with that short lever. If you're using an allen key on the back of
the pedal, you may not be getting enough leverage to make it secure.

Cheers,

Scott..

 

[Mark Hickey]

Jason <[email protected]> wrote:

>I have this reoccurring nightmare where my crank threads keep stripping. It always happens to the
>crank with the chain ring (right side). I've gone through 2 sets of cranks now, and I don't
>understand why it keeps happening. Is this normal? I do do a lot of hard pedaling, but me thinks
>that cranks and crank threads should be able to take such punishment.
>
>Any suggestions?

Not sure what kind of crank you have, but if I were to guess I'd say it's probably a crank with a
square spindle bottom bracket (crank axle), and that the crank bolts were not properly tightened
(which will result in a ruined crank almost every time).

It's almost impossible to properly tighten a crank bolt with a "normal" allen wrench - you really
need a torque wrench to get the feel for just how much torque is s'posed to be used.

They're a lot cheaper than new crank arms!

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

 

[Werehatrack]

On Sun, 19 Oct 2003 16:10:51 GMT, Jason <[email protected]> may have said:

>On Sun, 19 Oct 2003 16:00:27 +0000, Phil Brown wrote:
>
>>
>>>I have this reoccurring nightmare where my crank threads keep stripping.
>>
>> What do you mean by crank threads? What part is failing? Phil Brown
>
>It is the crank pedal threads that have been stripped. ie: The hole in which the pedal is screwed
>into. The pedal threads are fine, but only the right crank gets stripped. This has happened on 2
>sets of cranks.
>
>I also noticed that after the first time it happened; the right pedal spun crunchy. I had fixed the
>crunchy pedal spin before reinstalling on the second set. I have VP-550 pedals and Both Shimano and
>Sakae cranks.
>
>This is getting expensive.

After the second failure, I think I might have scrapped the pedals and replaced them; there may be
something wrong with the threaded stub which might not be obvious to anyone but a machinist.

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