Change of chainring like for like but now it won't change smoothly

Hi,

I've recently changed the middle chainring on my Dawes Audax. It has a
52/42/30 triple and as I use the middle chainring most it started to
slip when under load. I bought a new 42t ring, fitted it and now I've
got a problem I haven't had before. When I change down from the 52t
ring the edge of the chain sits on top of the teeth of the 42t ring.
It just doesn't move over towards the frame enough. If I set up the
front mech so it does move over enough it catches the front mech. It
is a new Shimano chain by the way.

If I move the rear mech over 3 or more gears it will change.

Can anyone help?

TIA

Alan

wrote:
Hi,

I've recently changed the middle chainring on my Dawes Audax. It has a
52/42/30 triple and as I use the middle chainring most it started to
slip when under load. I bought a new 42t ring, fitted it and now I've
got a problem I haven't had before. When I change down from the 52t
ring the edge of the chain sits on top of the teeth of the 42t ring.
It just doesn't move over towards the frame enough. If I set up the
front mech so it does move over enough it catches the front mech. It
is a new Shimano chain by the way.

If I move the rear mech over 3 or more gears it will change.

Is it /exactly/ like for like? Middle-specific chainring and not one
designed for a double inner?

Sorry I can't think of anything else at the moment.

~PB

Pete Biggs wrote:

wrote:

Hi,

I've recently changed the middle chainring on my Dawes Audax. It has a
52/42/30 triple and as I use the middle chainring most it started to
slip when under load. I bought a new 42t ring, fitted it and now I've
got a problem I haven't had before. When I change down from the 52t
ring the edge of the chain sits on top of the teeth of the 42t ring.
It just doesn't move over towards the frame enough. If I set up the
front mech so it does move over enough it catches the front mech. It
is a new Shimano chain by the way.

If I move the rear mech over 3 or more gears it will change.


Is it /exactly/ like for like? Middle-specific chainring and not one
designed for a double inner?

Sorry I can't think of anything else at the moment.

I think the front mech just needs adjusting. If there was a shifting
problem related to using a double inner on a triple setup (in fact, I do
this without any hassle) it would manifest itself as a failure to drop
off the middle onto the granny.

The OP should try slackening the cable a bit and adjusting the angle of
the mech. Some like to be "toed in" a little.

Like PB I wondered if I had been given a chainring for a double
instead of a triple. Does anyone know for sure whether there is a
difference.

Alan

Zog The Undeniable wrote:
Pete Biggs wrote:
wrote:
I've recently changed the middle chainring on my Dawes Audax. It
has a 52/42/30 triple and as I use the middle chainring most it
started to slip when under load. I bought a new 42t ring, fitted it
and now I've got a problem I haven't had before. When I change down
from the 52t ring the edge of the chain sits on top of the teeth of
the 42t ring. It just doesn't move over towards the frame enough.
If I set up the front mech so it does move over enough it catches
the front mech. It is a new Shimano chain by the way.

If I move the rear mech over 3 or more gears it will change.

Is it /exactly/ like for like? Middle-specific chainring and not one
designed for a double inner?

Sorry I can't think of anything else at the moment.

I think the front mech just needs adjusting.

Maybe it does, but why? Seems like it was working with the old ring.
What has changed?

If there was a shifting
problem related to using a double inner on a triple setup (in fact, I
do this without any hassle) it would manifest itself as a failure to
drop off the middle onto the granny.

Or change up from the granny (thhe pins pick up the chain).

I mentioned a middle-specific ring because Sheldon Brown suggested it as
an answer to a similar problem on r.b.t, but thinking again about it now,
I too don't see how it could help when shifting down from outer to middle.
The heat must have got to me!

~PB

Pete Biggs wrote:

Or change up from the granny (thhe pins pick up the chain).

True, although I'm blessed with a non-indexed FD which will shift on
anything (I use a 105 triple crankset with a 52T 105 outer ring, a 42T
TA "double inner" ring with no cutouts, ramps or pins and an unknown
make of 26T granny ring).

If the OP is using front indexing, it can take a lot of faffing to get
right. I have it on the MTB and it just about works, but it's a waste
of time IMO.