Front Derailleur. Phantom gear changes

Per Elmsäter said:

I just changed my chain as it was worn down to the 1.0 mark according to my Park Tool chain gauge.
When I took my bike out for a ride I thought at first the chain was skipping on the cogs which it
shouldn't as the casette have only gone this one chain that just was replaced according to good
practise. When I inspected closer what was happening, that when in the small ring up front ( 26,
36, 48 Nexave) the chain would start moving to the middle ring and then drop back, which kind of
felt like skipping a cog. This usually didn't happen until I was on the lowest gears. Then today
the chain started going off the little ring towards the inside when I put pressure on the pedals.
Long after I geared down. Like I'd see a steep hill and drop my chain to the small ring and start
climbing. After maybe 150 m of climbing when I was going slow in the lowest gears the chain would
just slide off to the inside of the front granny ring???? It felt really weird and I can't figure
out what is doing these strange things. The derailleur itself looks like it is centered pretty
much over each ring and the limits are set. Ie the limits are set so that I don't overshift my
chain going down to the sall ring. It seems that it kinda climbs out.

The bike is a 2001 Gary Fisher Utopia, hybrid The FD and rings are Nexave The new chain is Shimano
Deore The RD is Shimano XT and The cogset is 9 speed SRAM 11-31

Is this simply FD adjustments or is there something else spooking me? Why did it start when I
switched chains? Front rings have never been changed and are about three years old and 5000 km.

I set my bike in my workstand and spun the cranks slowly in the lowest gear ( 26-31)while applying
some pressure with the rear brake. I could clearly see that the chainline was pointing to the left
of the front granny ring and hence the chain was rubbing against one side of the ring. When I put
more pressure on the brake I could see that the chain started weaving sideways back and forth. I am
sure that if I could have put enough pressure on it the chain would have climbed off the front
granny ring to the inside ( left ). When looking at the chain from above, it would slowly move
inwards and then kind pop back out and immediadetly start wandering slowly inwards again and pop
back out. It seemed to be about 6-10 inches between each cycle. It definitely wasn't a single link
that did this. I am just getting more and more puzzled.

--
Perre

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Per Elmsäter said:

The FD and rings are Nexave

I went to the Shimano site to see the specs on Nexave, but there are quite a few Nexave lines.

Quoted message said:

The new chain is Shimano Deore

Is this simply FD adjustments or is there something else spooking me? Why

At first, I thought it was a matter of an incorrect FD. Then, I saw your description of working with

it on a stand; then I realized you also said:

did it start when I switched chains? Front rings have never been changed and are about three years
old and 5000 km.

I suspect you've got worn rings that don't match the new chain. The old chain was worn exactly the
same and fit nicely. The new chain would mesh nicely with crisp, new rings.

Since the damage is already done (I bet the cogs are the same), you might put the old chain back on
and ride it until something breaks. Then you'll need to replace rings, cassette, and chain.
--
Rick Onanian

Rick Onanian said:

Per Elmsäter said:

The FD and rings are Nexave

I went to the Shimano site to see the specs on Nexave, but there are quite a few Nexave lines.

Quoted message said:

The new chain is Shimano Deore

Is this simply FD adjustments or is there something else spooking me? Why

At first, I thought it was a matter of an incorrect FD. Then, I saw your description of working

with it on a stand; then I realized you also said:

did it start when I switched chains? Front rings have never been changed and are about three
years old and 5000 km.

I suspect you've got worn rings that don't match the new chain. The old chain was worn exactly the
same and fit nicely. The new chain would mesh nicely with crisp, new rings.

Since the damage is already done (I bet the cogs are the same), you might put the old chain back
on and ride it until something breaks. Then you'll need to replace rings, cassette, and chain.

I hope you're not right though I'm beginning to suspect the same thing myself. Although I don't see
any hooks on the rings and the cassette has only seen this one chain. I was looking for a cog tool
to measure cog wear the same as chain wear but haven't found one yet. Unfortunately I threw the old
chain away. I'll never do that again until I'm 100% everything is broken in right.

--
Perre

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Per Elmsäter said:

Unfortunately I threw the old chain away. I'll never do that again until I'm 100% everything is
broken in right.

Why in the world would you throw an old chain away? They have a million uses, starting with home-
made chain whips...

New drivetrain time! Yay! An excuse to get new toys! 😉
--
Rick Onanian