ghost shifts

Gary said:

Just bought a 10-speed triple with Ultegra - 30-42-52 in front and 12-25 in
the rear.  When I'm climbing in 2-2, the chain autoshifts onto the small
front ring. I put the bike onto a stand. It seems that the chain isn't
meshing with the teeth in that combination, and I think it is due to a bad
chain line. 2-3 or higher is fine. But in 2-2 the chain doesn't engage and
falls of onto the smaller ring. Now I'll admit that I probably shouldn't be
riding in 2-2, but is that supposed to happen? Shouldn't the bike allow me
to ride in 2-2? Is there anything I can do (besides not ride in 2-2)?

It should stay on each ring, regardless of which cog the chain is on
in the back, particularly when in the middle ring. If it is a
chainline problem, not much you can do anyway. I suspect a fder adjust
issue but tough to tell w/o seeing it. You know you do have a 'trim'
feature in the middle ring? You can move the Fder around a wee bit in
the middle ring to prevent chain rub when going to the extremes of the
cogset. BUT triple systems are designed to be able to use the entire
cogset in the middle ring with ease.

All I could see was that in 2-3 or higher the chain meshed cleanly, but when
I shifted down to 2-2, now the chain was emerging from the rear cluster from
a different location (further back and to the left), and now, the pins of
the chain were lining up with the teeth of my front chainring and not
settling into the valleys like they were supposed to. After about half a
turn of the crank, the chain would fall off the middle ring and settle onto
the small ring in front.
The worse part of all of this is that the STI shifter still thinks it's in
second gear and not in first, so I have to consciously downshift it, even
though the chain has already jumped.
Anyway, it's a new bike, so I'll take it into the shop and see what they can
do.

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Gary said:

Just bought a 10-speed triple with Ultegra - 30-42-52 in front and 12-25
in
the rear. When I'm climbing in 2-2, the chain autoshifts onto the small
front ring. I put the bike onto a stand. It seems that the chain isn't
meshing with the teeth in that combination, and I think it is due to a bad
chain line. 2-3 or higher is fine. But in 2-2 the chain doesn't engage and
falls of onto the smaller ring. Now I'll admit that I probably shouldn't
be
riding in 2-2, but is that supposed to happen? Shouldn't the bike allow me
to ride in 2-2? Is there anything I can do (besides not ride in 2-2)?

It should stay on each ring, regardless of which cog the chain is on
in the back, particularly when in the middle ring. If it is a
chainline problem, not much you can do anyway. I suspect a fder adjust
issue but tough to tell w/o seeing it. You know you do have a 'trim'
feature in the middle ring? You can move the Fder around a wee bit in
the middle ring to prevent chain rub when going to the extremes of the
cogset. BUT triple systems are designed to be able to use the entire
cogset in the middle ring with ease.