Bent chainring options?

[Joe]

I had been having difficulty with chain skip. I noticed this a few
days after I had been cut off by a small van, unavoidanbly crashing
into it, and landing on my right side. Minor scrapes and bruises to
me, and the bike.

On the workstand, with the chain removed, I can see a very tiny bit of
wobble on the outer chainring, and none on the middle. I taped some
stiff cardboard to the bike for a makeshift alignment gage, while
rotating the crank to detect rotational alignment. I noticed that my
small chainring is bent. It has about a 1/8" rise towards the crank
along a few teeth.

I can't tell if the spider is bent, although it does not appear to be.
There was no visible damage to the pedal, crankarm or rings. I did
land with my right foot locked to the pedal. Shifiting is fine with
only the chain skip problem when climbing 5-7% grades and shifting
into the second lowest gear. I let up on the pedalling when shifting.
One skip over a few teeth, and then it settles in.

If I first shift into the second lowest cog while on the middle
chainring, and then shift onto the small chainring the skip does not
occur.

The chainring is a Cannondale PX triple 30/42/52, and the bottom
bracket is a Shimano RSX.

My present crankset is a Cannondale PX 30/42/52. If the crankset has
to be replaced can I use the Shimano 105, 30/42/52, FC-5505 crankset?
Anyone know if the FC-5505 will fit my RSX bb?

Thanks,
Joe

[Mathias De Belder]

Joe wrote:

> I had been having difficulty with chain skip. I noticed this a few
> days after I had been cut off by a small van, unavoidanbly crashing
> into it, and landing on my right side. Minor scrapes and bruises to
> me, and the bike.

Heh, I had almost the exact same thing happening to me a few weeks ago.
Crashed, and 2 weeks later when I got back on my bike again, I noticed
the chain would skip wildly on the outer chainring. Turned out one of
the teeth in chainring was bent. A riding buddy of mine said that fixing
something like that is almost impossible, and that you're better off
getting a new chainring, which I did.

[Sheldon Brown]

A shy person wrote:

> I had been having difficulty with chain skip. I noticed this a few
> days after I had been cut off by a small van, unavoidanbly crashing
> into it, and landing on my right side. Minor scrapes and bruises to
> me, and the bike.
>
> On the workstand, with the chain removed, I can see a very tiny bit of
> wobble on the outer chainring, and none on the middle. I taped some
> stiff cardboard to the bike for a makeshift alignment gage, while
> rotating the crank to detect rotational alignment. I noticed that my
> small chainring is bent. It has about a 1/8" rise towards the crank
> along a few teeth.
>
> I can't tell if the spider is bent, although it does not appear to be.
> There was no visible damage to the pedal, crankarm or rings. I did
> land with my right foot locked to the pedal. Shifiting is fine with
> only the chain skip problem when climbing 5-7% grades and shifting
> into the second lowest gear. I let up on the pedalling when shifting.
> One skip over a few teeth, and then it settles in.

I have an article on Straightening Chainwheels, see:

http://sheldonbrown.com/straighten_chw.html

> The chainring is a Cannondale PX triple 30/42/52, and the bottom
> bracket is a Shimano RSX.
>
> My present crankset is a Cannondale PX 30/42/52. If the crankset has
> to be replaced can I use the Shimano 105, 30/42/52, FC-5505 crankset?

Yes.

> Anyone know if the FC-5505 will fit my RSX bb?

It will not, you'll need a new bottom bracket too, but this is much
cheaper than the crankset.

Sheldon "Upgrades" Brown
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[Joe]

On Mon, 14 Jul 2003 12:55:26 -0400, Sheldon Brown
> wrote:

>A shy person wrote:

A hirsute guru responded:

>
>I have an article on Straightening Chainwheels, see:
>
> http://sheldonbrown.com/straighten_chw.html

Thanks, that was the first thing I did prior to posting my question. I
was unable to apply enough leverage to the small ring at the
appropriate point to make a difference. Didn't want to apply a mallet
for fear of doing some unforseen damage.

>> My present crankset is a Cannondale PX 30/42/52. If the crankset has
>> to be replaced can I use the Shimano 105, 30/42/52, FC-5505 crankset?
>
>Yes.

Thanks again, good to know.
>
>> Anyone know if the FC-5505 will fit my RSX bb?
>
>It will not, you'll need a new bottom bracket too, but this is much
>cheaper than the crankset.

Gracias again.

Joe