Re: Fractured front cog?

[Daniel Kelly \(AKA Jack\)]

Sorry guys, it looks like my web host has gone offline.

Here are some photos that work:

Try these links:

http://www.ucl.ac.uk/~ucgadak/fracture1.jpg
http://www.ucl.ac.uk/~ucgadak/fracture2.jpg
http://www.ucl.ac.uk/~ucgadak/fracture3.jpg

Thanks!
Jack


"Daniel Kelly (AKA Jack)" > wrote in message
...
> Dear Bikers,
>
> I fear my bike has a fracture in its front cog. I first noticed something
> was wrong when I heard the front cog hitting against the front derailleur
> once every revolution of the pedals. It turned out the front cog was
> actually bent and so "wobbled" as it rotated, relative to the front
> derailleur. Closer inspection showed that the front cog was a little
loose
> and could be jiggled a little. The join between the front cog and the
right
> pedal was clearly loose.
>
> I took the right pedal off and found a little crack in the front cog.
Some
> photos are here:
>
>
http://www.xlk.org.uk/forum/modules.php?set_albumName=Bike&op=modload&name=gallery&file=index&include=view_album.php
>
> Is this a fracture? If so, how dangerous is it? Can I ride my bike with
> this fracture? Do I need a new front cog & right pedal?
>
> Thanks,
> Jack
>
>
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[Sheldon Brown]

Daniel Kelly (AKA Jack) wrote:

>>I fear my bike has a fracture in its front cog. I first noticed something
>>was wrong when I heard the front cog hitting against the front derailleur
>>once every revolution of the pedals. It turned out the front cog was
>>actually bent and so "wobbled" as it rotated, relative to the front
>>derailleur. Closer inspection showed that the front cog was a little
>> loose
>
>>and could be jiggled a little. The join between the front cog and the
>> right
>>pedal was clearly loose.
>>
>>I took the right pedal off and found a little crack in the front cog.
>
> Some
>
>>photos are here:
>>
> http://www.ucl.ac.uk/~ucgadak/fracture1.jpg
> http://www.ucl.ac.uk/~ucgadak/fracture2.jpg
> http://www.ucl.ac.uk/~ucgadak/fracture3.jpg

>>Is this a fracture?

Yes.

>>If so, how dangerous is it?

Not very.

>>Can I ride my bike with this fracture?

Probably, but it may cause shifting problems or chain rub.

>>Do I need a new front cog & right pedal?

You need a new crank, but there's no reason to think you need a pedal.

It seems you're a bit confused on the usual terminology.

The part you refer to as the front "cog" is more commonly called a
chainring or chainwheel.

The part you refer to as the "pedal" is actually the crank. In this
case the chainrings are permanently attached to the crank (though not as
permanently as one might wish!)

Higher-quality cranks generally have the chainrings bolted to them, so
you could replace the chainrings without buying a new crank, but yours
is not like this.

The pedal is the part you actually put your foot on. It screws into the
crank.

Sheldon "http://sheldonbrown.com/glossary" Brown
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[Leo Lichtman]

It looks to me like the break is right at the spline which transmits all the
pedalling torque to all three rings. If this opens a little bit while you
are pressing hard on a pedal, the whole thing could slip or collapse. Don't
pedal very hard until you get it replaced--the sooner the better.

[Leo Lichtman]

It looks to me like the break is right at the spline which transmits all the
pedalling torque to all three rings. If this opens a little bit while you
are pressing hard on a pedal, the whole thing could slip or collapse. Don't
pedal very hard until you get it replaced--the sooner the better.