Fractured front cog? - Page 7

07-06-2004, 05:10 AM

Daniel Kelly (AKA Jack) wrote:

>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:
>
>[Only registered and activated users can see links. ]
>
>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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>
Jack - your crankset appears to be worn out.
You need at least a new crankset, but more likely a new drive train...
chain, crankset (front chainrings & pedal crankarms in your case), rear
casset. It's a pity, but metal wears down.
Best, Bernie

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07-07-2004, 10:36 AM

An excellent summary of the problem and solution.

I might add that frequently the chain stretches over time and begins to chew
into the side of the chainring teeth. It also chews into the teeth of the
rear cassette (the cluster of rings on the back wheel). So if you replace
the chainrings, the old chain may give poor performance - grinding, chain
suck and such. I found that I had to replace them as a set on my bike.

Luckily I had a newer cassette to replace my old one on the back wheel.
Otherwise the new chain probably would have had bad shifting and skipping on
the rear cassette. Hope this doesn't happen to you, but be aware that if
the new crankset causes noise in the rear of your drive train, that's likely
the cause.

Cheers
Gary

"Werehatrack" <[Only registered and activated users can see links. ]> wrote in message
news:[Only registered and activated users can see links. ]...
> On Mon, 5 Jul 2004 11:03:27 CST, "Daniel Kelly \(AKA Jack\)"
> <[Only registered and activated users can see links. ].ac.uk> wrote:

< snip >

> Bear in mind that you may need to replace the bottom bracket (this is
> the confusing name used in the industry for the bearing and shaft
> assembly on which the cranks are mounted) if the length of your
> existing shaft is not a close match for the requirements of the
> replacement cranks.
>

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posting problems, or contact the moderators, please see [Only registered and activated users can see links. ]
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07-07-2004, 10:36 AM

An excellent summary of the problem and solution.

I might add that frequently the chain stretches over time and begins to chew
into the side of the chainring teeth. It also chews into the teeth of the
rear cassette (the cluster of rings on the back wheel). So if you replace
the chainrings, the old chain may give poor performance - grinding, chain
suck and such. I found that I had to replace them as a set on my bike.

Luckily I had a newer cassette to replace my old one on the back wheel.
Otherwise the new chain probably would have had bad shifting and skipping on
the rear cassette. Hope this doesn't happen to you, but be aware that if
the new crankset causes noise in the rear of your drive train, that's likely
the cause.

Cheers
Gary

"Werehatrack" <[Only registered and activated users can see links. ]> wrote in message
news:[Only registered and activated users can see links. ]...
> On Mon, 5 Jul 2004 11:03:27 CST, "Daniel Kelly \(AKA Jack\)"
> <[Only registered and activated users can see links. ].ac.uk> wrote:

< snip >

> Bear in mind that you may need to replace the bottom bracket (this is
> the confusing name used in the industry for the bearing and shaft
> assembly on which the cranks are mounted) if the length of your
> existing shaft is not a close match for the requirements of the
> replacement cranks.
>

--
rec.bicycles.off-road is moderated by volunteers. To find help solving
posting problems, or contact the moderators, please see [Only registered and activated users can see links. ]
Please read the charter before posting: [Only registered and activated users can see links. ]

07-07-2004, 10:36 AM

An excellent summary of the problem and solution.

I might add that frequently the chain stretches over time and begins to chew
into the side of the chainring teeth. It also chews into the teeth of the
rear cassette (the cluster of rings on the back wheel). So if you replace
the chainrings, the old chain may give poor performance - grinding, chain
suck and such. I found that I had to replace them as a set on my bike.

Luckily I had a newer cassette to replace my old one on the back wheel.
Otherwise the new chain probably would have had bad shifting and skipping on
the rear cassette. Hope this doesn't happen to you, but be aware that if
the new crankset causes noise in the rear of your drive train, that's likely
the cause.

Cheers
Gary

"Werehatrack" <[Only registered and activated users can see links. ]> wrote in message
news:[Only registered and activated users can see links. ]...
> On Mon, 5 Jul 2004 11:03:27 CST, "Daniel Kelly \(AKA Jack\)"
> <[Only registered and activated users can see links. ].ac.uk> wrote:

< snip >

> Bear in mind that you may need to replace the bottom bracket (this is
> the confusing name used in the industry for the bearing and shaft
> assembly on which the cranks are mounted) if the length of your
> existing shaft is not a close match for the requirements of the
> replacement cranks.
>

--
rec.bicycles.off-road is moderated by volunteers. To find help solving
posting problems, or contact the moderators, please see [Only registered and activated users can see links. ]
Please read the charter before posting: [Only registered and activated users can see links. ]

07-07-2004, 10:36 AM

An excellent summary of the problem and solution.

I might add that frequently the chain stretches over time and begins to chew
into the side of the chainring teeth. It also chews into the teeth of the
rear cassette (the cluster of rings on the back wheel). So if you replace
the chainrings, the old chain may give poor performance - grinding, chain
suck and such. I found that I had to replace them as a set on my bike.

Luckily I had a newer cassette to replace my old one on the back wheel.
Otherwise the new chain probably would have had bad shifting and skipping on
the rear cassette. Hope this doesn't happen to you, but be aware that if
the new crankset causes noise in the rear of your drive train, that's likely
the cause.

Cheers
Gary

"Werehatrack" <[Only registered and activated users can see links. ]> wrote in message
news:[Only registered and activated users can see links. ]...
> On Mon, 5 Jul 2004 11:03:27 CST, "Daniel Kelly \(AKA Jack\)"
> <[Only registered and activated users can see links. ].ac.uk> wrote:

< snip >

> Bear in mind that you may need to replace the bottom bracket (this is
> the confusing name used in the industry for the bearing and shaft
> assembly on which the cranks are mounted) if the length of your
> existing shaft is not a close match for the requirements of the
> replacement cranks.
>

--
rec.bicycles.off-road is moderated by volunteers. To find help solving
posting problems, or contact the moderators, please see [Only registered and activated users can see links. ]
Please read the charter before posting: [Only registered and activated users can see links. ]

07-07-2004, 10:36 AM

An excellent summary of the problem and solution.

I might add that frequently the chain stretches over time and begins to chew
into the side of the chainring teeth. It also chews into the teeth of the
rear cassette (the cluster of rings on the back wheel). So if you replace
the chainrings, the old chain may give poor performance - grinding, chain
suck and such. I found that I had to replace them as a set on my bike.

Luckily I had a newer cassette to replace my old one on the back wheel.
Otherwise the new chain probably would have had bad shifting and skipping on
the rear cassette. Hope this doesn't happen to you, but be aware that if
the new crankset causes noise in the rear of your drive train, that's likely
the cause.

Cheers
Gary

"Werehatrack" <[Only registered and activated users can see links. ]> wrote in message
news:[Only registered and activated users can see links. ]...
> On Mon, 5 Jul 2004 11:03:27 CST, "Daniel Kelly \(AKA Jack\)"
> <[Only registered and activated users can see links. ].ac.uk> wrote:

< snip >

> Bear in mind that you may need to replace the bottom bracket (this is
> the confusing name used in the industry for the bearing and shaft
> assembly on which the cranks are mounted) if the length of your
> existing shaft is not a close match for the requirements of the
> replacement cranks.
>

--
rec.bicycles.off-road is moderated by volunteers. To find help solving
posting problems, or contact the moderators, please see [Only registered and activated users can see links. ]
Please read the charter before posting: [Only registered and activated users can see links. ]