Pedal crank keeps coming loose.

Hello

I wonder if anyone could give me a clue about what might be happening with my
bike (a no-name MTB).

I've had it about 3 1/2 years and it's used daily.

Last week I noticed a slight clunk when pressing down on the left pedal - one
that could be felt but not heard. I assumed a bearing was going.

A few days later the crank became loose.

I bought a tool to retighten the nut that holds it onto the bar that runs
through the bottom bracket (sorry, I don't know the correct term for that -
pedal axel?).

What is odd, though is that no matter how hard a tighten it withing 5 minutes of
use the nut had unscrewed and the crank is loose. Also, even when tight, when
pressing down on the left pedal it makes a sort of creaking sound.

Any suggestions would be gratefully received.

Alan

"Alan" wrote in message
...
Hello

I wonder if anyone could give me a clue about what might be happening with
my
bike (a no-name MTB).

I've had it about 3 1/2 years and it's used daily.

Last week I noticed a slight clunk when pressing down on the left pedal -
one
that could be felt but not heard. I assumed a bearing was going.

A few days later the crank became loose.

I bought a tool to retighten the nut that holds it onto the bar that runs
through the bottom bracket (sorry, I don't know the correct term for
that -
pedal axel?).

What is odd, though is that no matter how hard a tighten it withing 5
minutes of
use the nut had unscrewed and the crank is loose. Also, even when tight,
when
pressing down on the left pedal it makes a sort of creaking sound.

Any suggestions would be gratefully received.

Alan


Hi try here, http://www.parktool.com/repair/readhowto.asp?id=123

John

"Alan" wrote in message
...
Hello

Last week I noticed a slight clunk when pressing down on the left pedal -
one
that could be felt but not heard. I assumed a bearing was going.

A few days later the crank became loose.

I bought a tool to retighten the nut that holds it onto the bar that runs
through the bottom bracket (sorry, I don't know the correct term for
that -
pedal axel?).

What is odd, though is that no matter how hard a tighten it withing 5
minutes of
use the nut had unscrewed and the crank is loose. Also, even when tight,
when
pressing down on the left pedal it makes a sort of creaking sound.

Any suggestions would be gratefully received.

Alan

The permanent fix is to fit a new crank which probably means buying a
complete chainset. Sadly what has happened to you is that the crank has
worked loose and the clunking around the square bottom bracket has worn a
shoulder or raised a ridge inside the square housing of the crank. You will
not get a snug fit on the crank no matter how hard you try and the crank
will always work loose. I had this happen to me on an Audax ride last year
and despite several tightenings the crank bolt loosesened itself enough to
fall off leading to the loss of the left hand crank. I had to pedal 4 - 5
miles one legged before I got to a bike shop in Ripon and a replacement
chain set was fitted.

-=V=-

vernon wrote:
"Alan" wrote in message
...

Hello

Last week I noticed a slight clunk when pressing down on the left pedal -
one
that could be felt but not heard. I assumed a bearing was going.

A few days later the crank became loose.

[snip]

Alan


The permanent fix is to fit a new crank which probably means buying a
complete chainset. [snip]

I was able to buy a LH crank on its own from the LBS earlier this week.
About £8 ISTR. It was for the the Peugot "racer" I mentioned in an
earlier thread which had a damaged crank taper exactly as you describe.

Peter




--
www.amey.org.uk

On Sat, 20 Jan 2007 17:38:26 -0000, "vernon" wrote:

The permanent fix is to fit a new crank which probably means buying a
complete chainset. Sadly what has happened to you is that the crank has
worked loose and the clunking around the square bottom bracket has worn a
shoulder or raised a ridge inside the square housing of the crank. You will
not get a snug fit on the crank no matter how hard you try and the crank
will always work loose. I had this happen to me on an Audax ride last year
and despite several tightenings the crank bolt loosesened itself enough to
fall off leading to the loss of the left hand crank. I had to pedal 4 - 5
miles one legged before I got to a bike shop in Ripon and a replacement
chain set was fitted.

This does seem to be what has happened. I looked on Wiggle for cranks, but they
all cost stupid money. You could get two bikes from Sterling House for the price
they want for a pair of cranks. (All right, not ones you'd actually want to
ride, but you get my point).

It's not like Wiggle not to be able to supply what you need. Am I searching for
the wrong thing (Cranks)? There are more crank tools than cranks.

On Sat, 20 Jan 2007 12:35:22 -0600, mb wrote:

On Sat, 20 Jan 2007 18:27:33 +0000, Alan wrote:


It's not like Wiggle not to be able to supply what you need. Am I searching for
the wrong thing (Cranks)? There are more crank tools than cranks.

You could also search for "chainset".

Unfortunately, again, only for stupid money.

This is a basic part that should only cost a tenner or so. (I only need the left
crank).

I'm rather perplexed.

Alan wrote:
On Sat, 20 Jan 2007 12:35:22 -0600, mb wrote:

On Sat, 20 Jan 2007 18:27:33 +0000, Alan wrote:

It's not like Wiggle not to be able to supply what you need. Am I searching for
the wrong thing (Cranks)? There are more crank tools than cranks.
You could also search for "chainset".

Unfortunately, again, only for stupid money.

This is a basic part that should only cost a tenner or so. (I only need the left
crank).

I'm rather perplexed.

Try ebay - a quick search for left crank brought in a few. Changing the
search terms could find more - but measure the one you've got (if it
doesn't have a length stamped on it), they do come in different lengths.
Also, look carefully at the fitting; you'll probably have square taper,
some of these have octalink (splined) fittings.

Matt

"Alan" wrote in message
...
On Sat, 20 Jan 2007 12:35:22 -0600, mb wrote:

On Sat, 20 Jan 2007 18:27:33 +0000, Alan wrote:


It's not like Wiggle not to be able to supply what you need. Am I
searching for
the wrong thing (Cranks)? There are more crank tools than cranks.

You could also search for "chainset".

Unfortunately, again, only for stupid money.

This is a basic part that should only cost a tenner or so. (I only need
the left
crank).

I'm rather perplexed.

Have a look at www.sjscycles.co.uk click on tranmission then crank sets,
you'll find a range of LH cranks from around £9.00 + p&p they all seem to
be 170mm long. I recall reading some debate somewhere where someone arguing
that equal cranklengths being essential and their argument being blasted out
of the water by someone who discovered that they'd been riding with
different crank lengths for several months and hadn't noticed.

Good luck with your search.

-=V=-

Alan brought next idea :

I looked on Wiggle for cranks, but
they all cost stupid money. You could get two bikes from Sterling House for
the price they want for a pair of cranks. (All right, not ones you'd actually
want to ride, but you get my point).

It's not like Wiggle not to be able to supply what you need. Am I searching
for the wrong thing (Cranks)? There are more crank tools than cranks.

There's no way you should have to buy a complete chainset (unless,
possibly, you want a perfect match), or indeed pay silly money for a
left-hand crank (unless you're trying to match an expensive model,
obviously).

What are the markings on the existing crank? If it's Shimano, for
example, it will have a part number starting FC***** . Shimano's UK
agents used to (It's been a few years since I was in the trade) hold
good stocks of replacement cranks, which were reasonably priced
(£10-ish for the basic models). You'll need to know the length, too -
it will probably be stamped on the crank somewhere.

Post back here with any clues about the identity of the chainset (the
cranks and chainrings combined) and I or someone else will probably be
able to suggest a source for a reasonably-priced replacement.

--
Simon

"Alan" wrote in message
...
On Sat, 20 Jan 2007 12:35:22 -0600, mb wrote:

On Sat, 20 Jan 2007 18:27:33 +0000, Alan wrote:


It's not like Wiggle not to be able to supply what you need. Am I
searching for
the wrong thing (Cranks)? There are more crank tools than cranks.

You could also search for "chainset".

Unfortunately, again, only for stupid money.

This is a basic part that should only cost a tenner or so. (I only need
the left
crank).

I'm rather perplexed.

If you know someone with reasonable engineering skills, get the crank
internal mating faces made true i.e flat and at 90 degrees to each other.
This will make the crank a loose fit on the axle but with the correct
geometry.
This looseness can then be compensated for by the judicious use of something
like, brass or stainless steel shims.