Cracked crank

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

My jinxed road bike continues to have problems. I noticed a creaking sound
from the cranks and was surprised to see this crack. The bottom bracket hex
nut was only "hand tight", so would this have caused this damage

No, but it doesn't help matters.

Quoted message said:

and does it
mean a new crank? TIA

I wouldn't suggest you turn another revolution on those.

--
Mark (MSA)
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"Simon Mason" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The bottom bracket hex
nut was only "hand tight", so would this have caused this damage

No - if anything, overtightening would be more likely to cause it, or
possibly greasing the interface between the crank and the axle (since this
facilitates overtightening).The nut is only hand tight because the square
taper is now an irregular quadrilateral taper, if you see what I mean!

Quoted message said:

and does it
mean a new crank?

Lets just say it's your teeth that will be biting tarmac very shortly if you
don't replace it! ;-)

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"Simon D" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"Simon Mason" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

The bottom bracket hex
nut was only "hand tight", so would this have caused this damage

No - if anything, overtightening would be more likely to cause it, or
possibly greasing the interface between the crank and the axle (since this
facilitates overtightening).

I dare you to go over to rec.bicycles.tech and offer this explanation there!

Quoted message said:

The nut is only hand tight because the square
taper is now an irregular quadrilateral taper, if you see what I mean!

The nut probably loosened originally because the crank squirmed up the taper.

Quoted message said:

Quoted message said:

and does it mean a new crank?

Lets just say it's your teeth that will be biting tarmac very shortly if you
don't replace it! ;-)

To which I would add, is your top tube harder than your family jewels?
--
Mark South: World Citizen, Net Denizen

Simon Mason said:

My jinxed road bike continues to have problems. I noticed a creaking sound
from the cranks and was surprised to see this crack. The bottom bracket hex
nut was only "hand tight", so would this have caused this damage and does it
mean a new crank? TIA
http://www.simonmason.karoo.net/zcrank.htm

Did you check the tightness of the bolts regularly? You shouldn't - a
retighten after the first 50 miles or so is fine, but then put the bolts
in with threadlock and don't touch them again (unless you need to get
the cranks off for some reason).

Crankbolts always come loose as the crank squirms up the taper to
relieve the pressure from the bolt. Retightening them just starts the
squirming process from a new point, and eventually it cracks. Greasing
has nothing to do with this, but may stop your crank seizing to the spindle.

Simon Mason said:

My jinxed road bike continues to have problems. I noticed a creaking sound
from the cranks and was surprised to see this crack. The bottom bracket hex
nut was only "hand tight", so would this have caused this damage and does it
mean a new crank? TIA
http://www.simonmason.karoo.net/zcrank.htm

As has been said, tightening it up too much casues this.A typical scenario
would be put it on, ride a while, realise the crank arm is slightly loose,
then retighten.Trouble is, the damage has already been done now, as the
taper has worn slightly inside, so you'll need to tighten it further to
get it tight, thus straining the ally, and then causing the crack you have
got.
No choice but to get a new one.
Parker International are reasonably priced, or for a bargian get Cycling
Weekly, and check out all the ads, there are a couple of places that sell
excess Campy stuff at bargain prices - Oldham Cycle Centre, and a place
near Hereford(Leominster?) IIRC, I've bought stuff off both of them and
can recommmend them, I got a Veloce cahinset recently for £37.
Alan.

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