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Chain skipping on large chain ring.



 
 
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  #1  
Old August 10th 05, 10:10 PM
Xyzzy
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Default Chain skipping on large chain ring.

This has me baffled.

I just replaced the chain on my bike. It had approximately 4000 miles
on it. I never had any problem with it, except over the last 1000 miles
it got slightly more noisy. It shifted perfectly and was a breeze to
tune. My Park CC-2 told me it was .5% worn, so I decided to replace it.
I don't have any calipers or machine rule to measure wear with, just
the CC-2.

So I replaced the chain. The cassette on the bike is relatively new. I
frequently swap cogs around between cassettes so some cogs are newer
than others. I recently switched to an 11-21 setup from a 12-25 so I
took 4 links out of the chain when I installed it. It now is 104 links
long instead of 108 links. It it sized to allow me to shift into the
big/big combo without putting the rear derailleur into the wheel. I
never use the big/big or small/small combo.

After putting on the new chain, everything works perfectly, except the
big ring. The small ring is smooth whether pedalling forwards or
backwards. The cassette is smooth and does not skip. The big ring,
however, has a bit of hooking action going on when pedalling forwards,
and if I pedal backwards the chain rides up the teeth every once in a
while and then plops back down where it is supposed to be.

Here is a pictu

http://www.teamendorphin.com/jpg/skip.jpg

I doubt the chain will suck up because of the tension on the chain from
the derailleur spring. I rarely pedal backwards so I would not normally
notice this skipping, except I do pedal the crank backwards when I
clean the chain, which is how I noticed this. The chain, BTW, is joined
with the Campy pin, not a quick link, in case this matters.

I compared the length of the old chain to the new chain and the old
chain was a little longer, but not a whole lot. My CC-2 won't even fit
into the new chain at all! Either my CC-2 is not calibrated properly or
the new chain is ultra tight.

I ride 99% of the time in the small ring. I can only think of 3 or 4
times, since I bought the bike, where I have used the big ring. I would
expect the small ring to wear out long before the large ring. I would
also expect the cassette to show significant wear before the chain
rings, and I definitely wouldn't expect to see wear in just a few
months. I have seen chain rings that are worn to nubs that still worked
fine.

I use ProLink to lube the chain and my chain is usually clean enough to
eat off of. I believe the chain only needs lubrication on the inside.
Any lube on the outside just collects dirt. I doubt lack of preventive
maintenance caused this. In fact, when I replaced the chain, I was able
to set the old chain down on my white carpet (Why do women like white
carpet?) without marking the floor, and this was after a 100 mile ride.
I've even read that a totally dry chain is just as efficient as one
that is oiled a bunch.

I cannot rotate or flip the large chain ring because it is pinned and
ramped and because it has an indexing mark/chain catcher thing that
tells you where to install it. I had heard that chain rings can develop
hooks where the area of greatest power is applied, but like I mentioned
I have maybe 20 miles on this ring and I'm certainly not known for
generating a lot of power.

What I think will happen is I will ride the bike for a few hundred
miles and the chain will stretch slightly and fit the large ring
properly. Since I rarely use the large ring this really isn't an issue
anyways. I'm just curious what is going on here.

Any ideas are appreciated! I really don't want to have to replace the
whole drivetrain so if this is going to cause abnormal wear I need to
know. I typically ride 200-400 miles a week.

Thanks!

--
Mike (Xyzzy)

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  #2  
Old August 11th 05, 02:01 PM
davy
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Default Chain skipping on large chain ring.

Mike,

your picture seems to show nicely cleaned worn chain rings. Assuming
that you've replaced the chain with the correct width chain and it
works with your cassette then replacement of the chain rings seems your
only option . (again confirm width of rings suitable for 9/10 speed set
up).

regards

Davy

  #3  
Old August 11th 05, 02:14 PM
Qui si parla Campagnolo
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Default Chain skipping on large chain ring.


Xyzzy wrote:
This has me baffled.


Any ideas are appreciated! I really don't want to have to replace the
whole drivetrain so if this is going to cause abnormal wear I need to
know. I typically ride 200-400 miles a week.

Thanks!

--
Mike (Xyzzy)


Is it happening at the same place eveytime on the ring? I have had to
file a tooth on a ring cuz it had a burr on it that made the chain do
what the pic looks like it is doing.

  #4  
Old August 11th 05, 02:43 PM
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Default Chain skipping on large chain ring.


Xyzzy wrote:
This has me baffled.

snip
I ride 99% of the time in the small ring. I can only think of 3 or 4
times, since I bought the bike, where I have used the big ring. I would
expect the small ring to wear out long before the large ring. I would
also expect the cassette to show significant wear before the chain
rings, and I definitely wouldn't expect to see wear in just a few
months. I have seen chain rings that are worn to nubs that still worked
fine.

snip

Just to be sure I'm reading you right, is it correct thayt:
1. the bike was bought new
2. there's about 4000 miles on the bike total
3. you haven't changed the chain or rings since new
?

It might just be the photo, but the large ring looks fairly tired -
there does appear to be some pronounced hooking on the teeth.
I know this doesn't tie in with what you said about milage etc., it jut
looks that way in the photo. Beats me how it could happen though...

If the teeth are significantly hooked, I'd suggest changing the ring(s)
when changing the chain. I'd also have a good look at the cassette,
and see if all is well there.

I think that the generally accepted wisdom is the more worn components
wear down new components faster than would be the case on all new
components, eg new chain on old rings - accelerated chain wear -
accelerated cassette wear. Everything gets worn down fairly quickly to
the level of the most worn component in the drivetrain.

You might also take the chance to change the tooth count on one or both
of your rings. If, as you say, you only use the large ring very
occasionally, the whole thing might be geared a little high for you,
and a smaller big ring might give you a more usable set of gears
overall.

HTH,

bookieb.

  #5  
Old August 11th 05, 07:05 PM
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Default Chain skipping on large chain ring.

Xyzzy (aka PLUGH) Michael Vang writes:

This has me baffled.


Here is a pictu


http://www.teamendorphin.com/jpg/skip.jpg


I just replaced the chain on my bike. It had approximately 4000
miles on it. I never had any problem with it, except over the last
1000 miles it got slightly more noisy. It shifted perfectly and was
a breeze to tune. My Park CC-2 told me it was .5% worn, so I
decided to replace it. I don't have any calipers or machine rule to
measure wear with, just the CC-2.


Any ideas are appreciated! I really don't want to have to replace the
whole drivetrain so if this is going to cause abnormal wear I need to
know. I typically ride 200-400 miles a week.


The picture you offer shows a worn out chain on a practically new
chainwheel. You'll notice that in the picture the chain is almost a
quarter inch off pitch in half the circumference of the sprocket (at
the bottom). Where did you get such a worn chain and why are you
using it?

Get a standard SRAM chain suitable for the width of your gears.

Jobst Brandt
  #6  
Old August 11th 05, 08:28 PM
O-V R:nen
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Default Chain skipping on large chain ring.

writes:
Xyzzy (aka PLUGH) Michael Vang writes:


http://www.teamendorphin.com/jpg/skip.jpg

The picture you offer shows a worn out chain on a practically new
chainwheel. You'll notice that in the picture the chain is almost a
quarter inch off pitch in half the circumference of the sprocket (at
the bottom). Where did you get such a worn chain and why are you
using it?


The chainrings look rather worn out as well if you look closely at
the shape of the teeth (although some of them do still seem quite
symmetrical).
  #7  
Old August 11th 05, 08:35 PM
Xyzzy
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Default Chain skipping on large chain ring.

The new chain is the exact same make and model (C10 Ultra) as the one
that came with the bike...

I rode the bike today for 100 miles and everything worked perfectly...
I didn't use the big ring since I never do... The small ring was silky
smooth and dead silent... Shifting was perfect as well and it never
skipped even under extreme climbing loads in (nearly) every gear...

Pedalling slowly backwards in the big ring here at home, off the bike,
the riding up on the teeth is much less pronounced now... My CC-2 chain
checker still will not fit into the chain...

--
Mike (Xyzzy)

  #8  
Old August 11th 05, 08:36 PM
Xyzzy
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Default Chain skipping on large chain ring.

It happens at random parts of the chain ring so I don't think it is a
burr...

--
Mike (Xyzzy)

  #9  
Old August 11th 05, 08:47 PM
Xyzzy
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Default Chain skipping on large chain ring.

This is the first time I changed the chain since the bike was new...
The bike has been ridden a few hundred miles by a friend of mine but I
can't see how, even if he used the big ring exclusively, that the big
ring could have worn out that fast... Aren't chain rings supposed to
last tens of thousands of miles? And even if it did wear out, why isn't
anything else ruined, like the small ring or the cassette? The bike is
an 05 model... We're not talking about a bike with 20-30,000 miles...

I only use the 18, 17, 16, 15, 14 and 13 cogs with the small ring...
Those gears are all I need where I live... That range covers me from 0
to 25 miles per hour... If I ever go faster than that I just coast or
spin out a bit... I'm a new rider so I am still trying to develop my
spin... When I started riding last summer I rode in the big ring
exclusively because I didn't know better... I also have a lot more
cardiovascular ability than leg strength so I trade big gears for high
cadence... I've ridden 51 centuries this year so far (I have a lot of
free time!) and all but a handful of those, from when I first started
out in January, are under 6 hours solo...

Even if I wanted to change the size of the front rings, it is (I
think!) a proprietary design... I could swap the whole deal out for a
"Hollowgram" carbon compact crank at great expense... I've emailed
Cannondale repeatedly to ask them if I can use ordinary Campagnolo
chain rings but I have never received a reply about that...

To be honest, for my usage patterns, this bike and its gearing suits me
fine...

  #10  
Old August 11th 05, 08:50 PM
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Default Chain skipping on large chain ring.

Otto-Ville Ronkainen writes:

http://www.teamendorphin.com/jpg/skip.jpg

The picture you offer shows a worn out chain on a practically new
chainwheel. You'll notice that in the picture the chain is almost
a quarter inch off pitch in half the circumference of the sprocket
(at the bottom). Where did you get such a worn chain and why are
you using it?


The chainrings look rather worn out as well if you look closely at
the shape of the teeth (although some of them do still seem quite
symmetrical).


The chainring is essentially new and as the user states has barely any
mileage. The tooth profile of interest is the silhouette of the tooth,
not its shiny wear contact or other reflective properties.

As I mentioned, the chain is off pitch by nearly 1/4 inch where it
exits at the bottom of the picture. There is no way this disparity
can be caused by a chainring in any any condition tooth spacing does
not change with wear. This chain is badly out of pitch... worn out.
There is no dodging that.

This chainwheel is worn but still works fine with a new chain:

http://home.comcast.net/~carlfogel/download/zzz_006.jpg

Jobst Brandt
 




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