Pedal crank keeps coming loose.

[Alan]

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

 

[John]

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

 

[vernon]

"Alan" <[email protected]> wrote in message
news:[email protected]...
> 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=-

 

[Peter Amey]

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

 

[Alan]

On Sat, 20 Jan 2007 17:38:26 -0000, "vernon" <[email protected]> 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.

 

[mb]

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".

--
Mike
Van Tuyl titanium Dura Ace 10
Fausto Coppi aluminium Ultegra 10
Raleigh Record Sprint mongrel

 

[Alan]

On Sat, 20 Jan 2007 12:35:22 -0600, mb <[email protected]> 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.

 

[Matthew Haigh]

Alan wrote:
> On Sat, 20 Jan 2007 12:35:22 -0600, mb <[email protected]> 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

 

[vernon]

"Alan" <[email protected]> wrote in message
news:[email protected]...
> On Sat, 20 Jan 2007 12:35:22 -0600, mb <[email protected]> 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=-

 

[Simon D]

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

 

[MJP]

"Alan" <[email protected]> wrote in message
news:[email protected]...
> On Sat, 20 Jan 2007 12:35:22 -0600, mb <[email protected]> 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.

 

[mb]

On Sat, 20 Jan 2007 21:21:50 +0000, MJP wrote:

>
> 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.

You don't seem to know what you're talking about. Go away.

--
Mike
Van Tuyl titanium Dura Ace 10
Fausto Coppi aluminium Ultegra 10
Raleigh Record Sprint mongrel

 

[vernon]

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

> 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.
Been there, done that, doesn't work. One has to get the taper *exactly*
correct - there's no room for error. The effort to sort out the problem
quite simply isn't worth it. Finding the: 'someone with reasonable
engineering skills' needs to accompanied with them having access to
reasonable engineering facilities. Such folk as as rare as the mythical
'KeilKraft long grass' that the eponymous manufacturer urged its customers
to test glide their freshly constructed model aeroplanes over.

 

[Don Whybrow]

vernon wrote:
>
> 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.

I rode around for a while with unequal crank lengths after the LBS
stripped the threads when trying to remove an old set of pedals. The
only LH crank they had in stock was 5 mm longer than the RH one. I never
noticed after a few miles.

One other thing to watch out for is the orientation of the square hole
in the crank. Some are in line with the crank and others are at 45
degrees so you either have a square or diamond hole. If you fit
different ones to different sides, it could make peddling awkward.


--
Don Whybrow

Sequi Bonum Non Time

Evolution is a harsh mistress.

 

[Sandy Morton]

In article <[email protected]>, Alan
<[email protected]> wrote:
> 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.

Sorry to be late on this one - I was Curling today.

Don't think about replacing it - the taper will have belled and will
be useless on a bike but don't throw it away.

Your LBS will be able to sell you one and give you change from a
tenner - if you want them to fit it a tenner should suffice.

Arguments start!

Don't grease it but fit it dry and belt it up as tightly as you can -
oil on the bolt/nut is OK. I use a Campag ratchet with a bit of gas
pipe welded to the handle for extra leverage. I don't get returns.

Arguments end!

The old crank would be valuable to many Model Engineers since it is
normally made of good quality alloy - I have made a few 1cc engines
using them and a few other bits and pieces

--
T h e - e x t e n d e r ! ! ! !

 

[MJP]

"mb" <[email protected]> wrote in message
news:[email protected]...
> On Sat, 20 Jan 2007 21:21:50 +0000, MJP wrote:
>
>>
>> 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.
>
> You don't seem to know what you're talking about. Go away.
>
> --
You are not an engineer then?

 

[Rob Morley]

In article <[email protected]>, Alan
[email protected] says...
> On Sat, 20 Jan 2007 12:35:22 -0600, mb <[email protected]> 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.
>
>
http://froogle.google.co.uk/froogle?q=left-hand-crank&scoring=p

 

[Rob Morley]

In article <[email protected]>,
MJP
[email protected] says...
>
> "mb" <[email protected]> wrote in message
> news:[email protected]...
> > On Sat, 20 Jan 2007 21:21:50 +0000, MJP wrote:
> >
> >>
> >> 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.
> >
> > You don't seem to know what you're talking about. Go away.
> >
> >
> You are not an engineer then?
>
A replacement crank will cost him a tenner - what do you think the cost
would be to do a one-off machining job like that even if he could find
someone with the right kit who was willing to do it? And he'd still
have a crank that didn't fit properly.

 

[Tony Raven]

MJP wrote on 21/01/2007 01:11 +0100:
> "mb" <[email protected]> wrote in message
> news:[email protected]...
>> On Sat, 20 Jan 2007 21:21:50 +0000, MJP wrote:
>>
>>> 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.
>> You don't seem to know what you're talking about. Go away.
>>
>> --
> You are not an engineer then?
>
>

I am and I'm with mb.

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
Douglas Adams; The Hitchhiker's Guide to the Galaxy

 

[Simon Brooke]

in message <[email protected]>, Sandy Morton
('[email protected]') wrote:

> In article <[email protected]>, Alan
> <[email protected]> wrote:
>> 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.
>
> Sorry to be late on this one - I was Curling today.

Where!? Oh, indoor, I presume.

Is there ever going to be a winter?

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; Sending your money to someone just because they've erected
;; a barrier of obscurity and secrets around the tools you
;; need to use your data does not help the economy or spur
;; innovation. - Waffle Iron Slashdot, June 16th, 2002