Need help figuring out why my chain is slipping!

Helen said:

Hello,

My bike has Dura Ace 10 speed (double chainring on the front and 12-27
cassette on the back) and STI shifting. When I'm in the small front chain
ring and the 24 rear cog (actually, the third and fourth cogs from the top),
my chain slips almost continuously. It's even worse when I'm putting more
power on the pedals, but it'll pretty much slip anytime when it's in those
cogs.

I've noticed that shifting up to the 27 cog then back down to the 23 helps a
bit, but usually not for long. I've just had both the chainrings , chain,
and the rear cassette replaced, but nothing helped! Before I take back to
my LEBS (again!), could someone give me an idea about possible causes?

Thanks,
Helen

When I had that problem it was because the cassette was worn.

Ken
--
New cycling jersey: $49
new cycling shorts: $39
Not being a slave to the petrol pump: priceless.

Helen said:

My bike has Dura Ace 10 speed (double chainring on the front and 12-27
cassette on the back) and STI shifting. When I'm in the small front chain
ring and the 24 rear cog (actually, the third and fourth cogs from the
top), my chain slips almost continuously. It's even worse when I'm
putting more power on the pedals, but it'll pretty much slip anytime when
it's in those cogs.

You mean the chain skips (pedals turn without driving the wheels)?

Quoted message said:

I've noticed that shifting up to the 27 cog then back down to the 23 helps
a bit, but usually not for long. I've just had both the chainrings ,
chain, and the rear cassette replaced, but nothing helped! Before I take
back to my LEBS (again!), could someone give me an idea about possible
causes?

Did the LBS recommend replacing both chainrings? If so, I would look for
another shop. What was the total cost of all that maintenance? I think they
owe it to you to resolve the probem.

Check that the cassette cogs are evenly spaced and that the locknut is
tight. Check that the rear der cable tension is correct and that the cable
to the rear der is anchored at the correct place. Check that the chain
length is correct and that there are no stiff links. Check that the inner
shift cable is not binding, and that the under BB cable guides are clean and
lubed.

Art Harris

Thanks for such an informative answer!

Quoted message said:

You mean the chain skips (pedals turn without driving the wheels)?

Yes. The pedals turn, but the chain is not biting fully into the cog. It
might skip up or down a cog. This ONLY happens in the 23 and 24 cogs (and
small front chainring.) All the other ones are fine.

Quoted message said:

Did the LBS recommend replacing both chainrings? If so, I would look for >
another shop. What was the total cost of all that maintenance? I think
they owe it to you to resolve the probem.

I think they just don't know what they're doing. I'm planning on taking the
bike to another LBS, but I want to go there with some idea of what to talk
about with the mechanic.

Thanks again!
Helen

"Arthur Harris" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Helen said:

My bike has Dura Ace 10 speed (double chainring on the front and 12-27
cassette on the back) and STI shifting. When I'm in the small front chain
ring and the 24 rear cog (actually, the third and fourth cogs from the
top), my chain slips almost continuously. It's even worse when I'm
putting more power on the pedals, but it'll pretty much slip anytime when
it's in those cogs.

You mean the chain skips (pedals turn without driving the wheels)?

Quoted message said:

I've noticed that shifting up to the 27 cog then back down to the 23
helps a bit, but usually not for long. I've just had both the chainrings
, chain, and the rear cassette replaced, but nothing helped! Before I
take back to my LEBS (again!), could someone give me an idea about
possible causes?

Did the LBS recommend replacing both chainrings? If so, I would look for
another shop. What was the total cost of all that maintenance? I think
they owe it to you to resolve the probem.

Check that the cassette cogs are evenly spaced and that the locknut is
tight. Check that the rear der cable tension is correct and that the cable
to the rear der is anchored at the correct place. Check that the chain
length is correct and that there are no stiff links. Check that the inner
shift cable is not binding, and that the under BB cable guides are clean
and lubed.

Art Harris

Helen said:

Thanks for such an informative answer!

Quoted message said:

You mean the chain skips (pedals turn without driving the wheels)?

Yes. The pedals turn, but the chain is not biting fully into the cog. It
might skip up or down a cog. This ONLY happens in the 23 and 24 cogs (and
small front chainring.) All the other ones are fine.

Quoted message said:

Did the LBS recommend replacing both chainrings? If so, I would look for >
another shop. What was the total cost of all that maintenance? I think
they owe it to you to resolve the probem.

I think they just don't know what they're doing. I'm planning on taking the
bike to another LBS, but I want to go there with some idea of what to talk
about with the mechanic.

Sounds like either the RD isn't adjusted correctly, the inner wire
isn't atached to the RD properly or perhaps it's a 9s chain....

Quoted message said:

Thanks again!
Helen

"Arthur Harris" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Helen said:

My bike has Dura Ace 10 speed (double chainring on the front and 12-27
cassette on the back) and STI shifting. When I'm in the small front chain
ring and the 24 rear cog (actually, the third and fourth cogs from the
top), my chain slips almost continuously. It's even worse when I'm
putting more power on the pedals, but it'll pretty much slip anytime when
it's in those cogs.

You mean the chain skips (pedals turn without driving the wheels)?

Quoted message said:

I've noticed that shifting up to the 27 cog then back down to the 23
helps a bit, but usually not for long. I've just had both the chainrings
, chain, and the rear cassette replaced, but nothing helped! Before I
take back to my LEBS (again!), could someone give me an idea about
possible causes?

Did the LBS recommend replacing both chainrings? If so, I would look for
another shop. What was the total cost of all that maintenance? I think
they owe it to you to resolve the probem.

Check that the cassette cogs are evenly spaced and that the locknut is
tight. Check that the rear der cable tension is correct and that the cable
to the rear der is anchored at the correct place. Check that the chain
length is correct and that there are no stiff links. Check that the inner
shift cable is not binding, and that the under BB cable guides are clean
and lubed.

Art Harris

Helen said:

Thanks for such an informative answer!

Quoted message said:

You mean the chain skips (pedals turn without driving the wheels)?

Yes. The pedals turn, but the chain is not biting fully into the cog. It
might skip up or down a cog. This ONLY happens in the 23 and 24 cogs (and
small front chainring.) All the other ones are fine.

It's almost certainly a worn cassette. You'll want to replace the
chain when you replace the cassette as well. I'm guessing you spend
most of your riding time in the cogs you're having trouble with
(though for the life of me, I can't imagine a cassette with a 23 AND a
24 tooth cog). The reason it happens in the small ring is that you're
applying more tension to the chain than you can with the big ring.

Just for grins, you should make sure that the rear derailleur "lines
up" with those cogs when you've shifted to those gears. Shift to the
adjacent gear, and notice the angle the chain takes between the cog
and the rear derailleur's top pulley (should be pretty much straight
up/down). Now shift to the 23, and verify that the chain angle is the
same. If it's not, it's possible that you have some cable friction /
derailleur issue that's leaving the chain "between gears".

Quoted message said:

Quoted message said:

Did the LBS recommend replacing both chainrings? If so, I would look for >
another shop. What was the total cost of all that maintenance? I think
they owe it to you to resolve the probem.

I think they just don't know what they're doing. I'm planning on taking the
bike to another LBS, but I want to go there with some idea of what to talk
about with the mechanic.

Chances are the chainrings are OK, though you will want to do a visual
inspection to make sure the teeth aren't really nasty.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Quoted message said:

Thanks again!
Helen

"Arthur Harris" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Helen said:

My bike has Dura Ace 10 speed (double chainring on the front and 12-27
cassette on the back) and STI shifting. When I'm in the small front chain
ring and the 24 rear cog (actually, the third and fourth cogs from the
top), my chain slips almost continuously. It's even worse when I'm
putting more power on the pedals, but it'll pretty much slip anytime when
it's in those cogs.

You mean the chain skips (pedals turn without driving the wheels)?

Quoted message said:

I've noticed that shifting up to the 27 cog then back down to the 23
helps a bit, but usually not for long. I've just had both the chainrings
, chain, and the rear cassette replaced, but nothing helped! Before I
take back to my LEBS (again!), could someone give me an idea about
possible causes?

Did the LBS recommend replacing both chainrings? If so, I would look for
another shop. What was the total cost of all that maintenance? I think
they owe it to you to resolve the probem.

Check that the cassette cogs are evenly spaced and that the locknut is
tight. Check that the rear der cable tension is correct and that the cable
to the rear der is anchored at the correct place. Check that the chain
length is correct and that there are no stiff links. Check that the inner
shift cable is not binding, and that the under BB cable guides are clean
and lubed.

Art Harris

Mark Hickey said:

It's almost certainly a worn cassette.

No. In her initial post she said, "I've just had both the chainrings ,
chain,
and the rear cassette replaced,"

Art Harris

I should have posted here BEFORE bringing the bike to the LBS! You guys are
great!

That's correct: I have just had the rear cassette, the front chainrings,
and the chain replaced. Because the skipping only occurs in the 22 (?) and
24 cogs, I figured, as Mark said, that I had worn down those particular cogs
because I do ride in them often.

However, after about 50 km with the new cassette, the chain started clunking
and skipping again. It was actually doing really well until I crossed a
local 500m pedestrian bridge that really rattles yer bones (the bridge is
made of 2x4s). Could the rattling have shaken something loose or undone an
adjustment?

Helen

"Mark Hickey" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Helen said:

Thanks for such an informative answer!

Quoted message said:

You mean the chain skips (pedals turn without driving the wheels)?

Yes. The pedals turn, but the chain is not biting fully into the cog. It
might skip up or down a cog. This ONLY happens in the 23 and 24 cogs (and
small front chainring.) All the other ones are fine.

It's almost certainly a worn cassette. You'll want to replace the
chain when you replace the cassette as well. I'm guessing you spend
most of your riding time in the cogs you're having trouble with
(though for the life of me, I can't imagine a cassette with a 23 AND a
24 tooth cog). The reason it happens in the small ring is that you're
applying more tension to the chain than you can with the big ring.

Just for grins, you should make sure that the rear derailleur "lines
up" with those cogs when you've shifted to those gears. Shift to the
adjacent gear, and notice the angle the chain takes between the cog
and the rear derailleur's top pulley (should be pretty much straight
up/down). Now shift to the 23, and verify that the chain angle is the
same. If it's not, it's possible that you have some cable friction /
derailleur issue that's leaving the chain "between gears".

Quoted message said:

Quoted message said:

Did the LBS recommend replacing both chainrings? If so, I would look for
>
another shop. What was the total cost of all that maintenance? I think
they owe it to you to resolve the probem.

I think they just don't know what they're doing. I'm planning on taking
the
bike to another LBS, but I want to go there with some idea of what to talk
about with the mechanic.

Chances are the chainrings are OK, though you will want to do a visual
inspection to make sure the teeth aren't really nasty.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Quoted message said:

Thanks again!
Helen

"Arthur Harris" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"Helen" wrote:
> My bike has Dura Ace 10 speed (double chainring on the front and 12-27
> cassette on the back) and STI shifting. When I'm in the small front
> chain
> ring and the 24 rear cog (actually, the third and fourth cogs from the
> top), my chain slips almost continuously. It's even worse when I'm
> putting more power on the pedals, but it'll pretty much slip anytime
> when
> it's in those cogs.

You mean the chain skips (pedals turn without driving the wheels)?

> I've noticed that shifting up to the 27 cog then back down to the 23
> helps a bit, but usually not for long. I've just had both the
> chainrings
> , chain, and the rear cassette replaced, but nothing helped! Before I
> take back to my LEBS (again!), could someone give me an idea about
> possible causes?

Did the LBS recommend replacing both chainrings? If so, I would look for
another shop. What was the total cost of all that maintenance? I think
they owe it to you to resolve the probem.

Check that the cassette cogs are evenly spaced and that the locknut is
tight. Check that the rear der cable tension is correct and that the
cable
to the rear der is anchored at the correct place. Check that the chain
length is correct and that there are no stiff links. Check that the
inner
shift cable is not binding, and that the under BB cable guides are clean
and lubed.

Art Harris

Helen said:

That's correct: I have just had the rear cassette, the front chainrings,
and the chain replaced. Because the skipping only occurs in the 22 (?) and
24 cogs, I figured, as Mark said, that I had worn down those particular cogs
because I do ride in them often.

However, after about 50 km with the new cassette, the chain started clunking
and skipping again. It was actually doing really well until I crossed a
local 500m pedestrian bridge that really rattles yer bones (the bridge is
made of 2x4s). Could the rattling have shaken something loose or undone an
adjustment?

I don't think the rough road is a factor.

Can you shift into the 27 tooth cog ok, and does the chain behave
itself there even under load?

Try suspending the bike off the ground using hooks or ropes. Shift to
the smallest cog. Then shift up one cog at a time, and listen for any
unusual grinding noises. The chain should shift smoothly and quietly
through all the cogs. If not, you may want to try adjusting either the
knurled knob where the der housing meets the derailleur, or the tension
adjusting lever on the down tube (if you have one).

There's a slight chance your rear dropout is bent out of alignment.
Sight from behind to make sure your der cage is perfectly vertical.
Shops have a tool to check and adjust the alignment.

See:

http://sheldonbrown.com/derailer-adjustment.html

Art Harris

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

Quoted message said:

Hello,

My bike has Dura Ace 10 speed (double chainring on the front and 12-27
cassette on the back) and STI shifting. When I'm in the small front chain
ring and the 24 rear cog (actually, the third and fourth cogs from the
top), my chain slips almost continuously. It's even worse when I'm
putting more power on the pedals, but it'll pretty much slip anytime when
it's in those cogs.

I've noticed that shifting up to the 27 cog then back down to the 23 helps
a bit, but usually not for long. I've just had both the chainrings ,
chain, and the rear cassette replaced, but nothing helped! Before I take
back to my LEBS (again!), could someone give me an idea about possible
causes?

Thanks,
Helen

This may sound crazy but it has happened to me. Are you sure the LBS
actually replaced the chain and cassette? I ask this because, as others
have
noted, it sounds so much like a worn casssette.

I bought a new bike from our incompetent LBS. I returned it to them
shortly after buying it to replace the stem and rear cassette because
they were different from what I had specified when I ordered the bike.
Although they specifically told me they replaced the rear cassette,
they in fact had not (or they replaced it with another new identical one
with the
same wrong cluster, I never new which).

BobT

Helen said:

I should have posted here BEFORE bringing the bike to the LBS! You guys are
great!

That's correct: I have just had the rear cassette, the front chainrings,
and the chain replaced. Because the skipping only occurs in the 22 (?) and
24 cogs, I figured, as Mark said, that I had worn down those particular cogs
because I do ride in them often.

However, after about 50 km with the new cassette, the chain started clunking
and skipping again. It was actually doing really well until I crossed a
local 500m pedestrian bridge that really rattles yer bones (the bridge is
made of 2x4s). Could the rattling have shaken something loose or undone an
adjustment?

Helen

Another possibility -- your freehub may be skipping. I had a Shimano one
fail this way a couple of years ago, it would skip just like a worn
cassette -- occasionally, and usually when using extra force. It had me
baffled for a while.

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

Quoted message said:

I should have posted here BEFORE bringing the bike to the LBS! You guys
are great!

That's correct: I have just had the rear cassette, the front chainrings,
and the chain replaced.

Given that they are 10-speed, the drivetrain is likely less than a year old.
So unless you are riding mega miles, the rings and cassette are not worn
out. The chain will wear out first, and is a throwaway after 6 months.

They replaced both rings and the cassette? Wow. I hope you got your old
parts back, otherwise the shop guys have got them on Ebay.

Could not this problem be as simple as a bent derailleur hanger, or a
9-speed chain on a 10-speed cassette? Or even a simple spin of the
derailleur barrel adjuster?

On Sun, 07 May 2006 02:16:54 GMT, "Dave Mayer" <[email hidden]>

Quoted message said:

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

Quoted message said:

I should have posted here BEFORE bringing the bike to the LBS! You guys
are great!

That's correct: I have just had the rear cassette, the front chainrings,
and the chain replaced.

Given that they are 10-speed, the drivetrain is likely less than a year old.
So unless you are riding mega miles, the rings and cassette are not worn
out. The chain will wear out first, and is a throwaway after 6 months.

They replaced both rings and the cassette? Wow. I hope you got your old
parts back, otherwise the shop guys have got them on Ebay.

Could not this problem be as simple as a bent derailleur hanger, or a
9-speed chain on a 10-speed cassette? Or even a simple spin of the
derailleur barrel adjuster?

So, if I follow your advice, I should throw away my chain every 6
months, no matter how many miles I ride. Is that your contention?

In reality chain's wear from use, not time.

Jeff

Art Harris said:

Mark Hickey said:

It's almost certainly a worn cassette.

No. In her initial post she said, "I've just had both the chainrings ,
chain,
and the rear cassette replaced,"

Oops. Mea Culpa...

My second paragraph still applies though. ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Helen said:

Hello,

My bike has Dura Ace 10 speed (double chainring on the front and 12-27
cassette on the back) and STI shifting. When I'm in the small front chain
ring and the 24 rear cog (actually, the third and fourth cogs from the top),
my chain slips almost continuously. It's even worse when I'm putting more
power on the pedals, but it'll pretty much slip anytime when it's in those
cogs.

I've noticed that shifting up to the 27 cog then back down to the 23 helps a
bit, but usually not for long. I've just had both the chainrings , chain,
and the rear cassette replaced, but nothing helped! Before I take back to
my LEBS (again!), could someone give me an idea about possible causes?

Thanks,
Helen

I tried cable rerouting, playing with cable tension, rear derailor
alignment and I even replaced the cassette, None of this worked. My
second to last resort was to buy new shifters. The absolute last resort
was to just sell it and get a new bike. To make a long story short, I
figured that either my frame was out of alignment at the rear dropout
or the chainline was out of sync somehow. I decided to try putting a
2mm washer between the cassette body and the dropout. Phew! It worked
problem solved.