new chainrings, bad shifting

[Ned Mantei[_2_]]

I've been riding the same mountain bike since 2003, and have been just
replacing things as they wear out or break. The components are now
mostly a mix of XT and LX. The relevant parts here are an XT front
derailleur from 2003, an LX FC-M580 crankset from 2007, and an XT M770
model front shifter that I had to install in September (shift cable
broke within the shifter and I couldn't get it out). This all seemed to
work fine with the 22/32/44 and 11-34 gearing. Just before Christmas I
replaced the chain, a SRAM PC 971, as I typically do every year and a
half or so. The middle chainring (32 teeth) was worn and didn't engage
properly with the new chain, so I replaced it with an XT M760 (along
with a 22-tooth SLX chainring that I happened to have). Afterwards
shifting between the 32-tooth and 44-tooth chainrings still worked fine,
but shifting either from the small to the middle or from the middle down
to the small chainring pretty much stopped working. With the derailleur
set so that I could shift down to the small chainring, shifting back to
the middle required an extra movement of the shifter beyond the middle
setting. A setting that would allow shifting up to the 32-tooth
chainring meant that I couldn't shift back to the 22-tooth one. The
derailleur would move, but the chain would hang on the middle chainring.
A very competent LBS suggested that the new 32-tooth chainring might not
be appropriate for the crankset, so I bought one (part # Y1FU98020) that
is specifically for the FC-M580 crank. Still very poor shifting. I
could find an adjustment so that it sort of works: shifting from the
middle to the small chainring usually works as long as I pause, shift,
and then move the pedals. Shifting back up to the middle usually works
if I shift while moving the pedals without hesitation. Neither works
every time, whereas earlier it would have worked every time without any
conscious thought.

Is this fixable? Thanks for any suggestions or advice.

I like this bike because it fits me and because it's like an old friend
that has accompanied me to so many out-of-the-way places (for example
here: https://flic.kr/p/a7w3LM ), but now am wondering whether it might
be time to give up.



Regards,
Ned

[[email protected]]

I did not read the question but understand replacing one part CR requires replacing the other 2

replacing chain requires replacing cogs and CR if the CR is worn past X

seeing cog wear is difficult. For example, losing track of which cog came off and which is the new cog set is not in order.

The Harris Sheldon Brown web advisor has visuals on this.

[[email protected]]

On Sunday, December 27, 2015 at 5:06:02 PM UTC-5, wrote:
> I did not read the question but understand replacing one part CR requires replacing the other 2
>
> replacing chain requires replacing cogs and CR if the CR is worn past X
>
> seeing cog wear is difficult. For example, losing track of which cog came off and which is the new cog set is not in order.
>
> The Harris Sheldon Brown web advisor has visuals on this.

yeah replace everything... are the derays wobbly on the pivots ?

are the drive train surfaces in line ? run a string with 1/2" ply shims from down tube to cogs...how's the CR surface line up ? is the rear deray in line off its hanger as the rig shifts ? ( first AMUZI advice years ago)

there's prob a utube animation for adjusting the front deray.

tweek tweek twek

[John B.[_6_]]

On Sun, 27 Dec 2015 20:36:46 +0100, Ned Mantei
> wrote:

>I've been riding the same mountain bike since 2003, and have been just
>replacing things as they wear out or break. The components are now
>mostly a mix of XT and LX. The relevant parts here are an XT front
>derailleur from 2003, an LX FC-M580 crankset from 2007, and an XT M770
>model front shifter that I had to install in September (shift cable
>broke within the shifter and I couldn't get it out). This all seemed to
>work fine with the 22/32/44 and 11-34 gearing. Just before Christmas I
>replaced the chain, a SRAM PC 971, as I typically do every year and a
>half or so. The middle chainring (32 teeth) was worn and didn't engage
>properly with the new chain, so I replaced it with an XT M760 (along
>with a 22-tooth SLX chainring that I happened to have). Afterwards
>shifting between the 32-tooth and 44-tooth chainrings still worked fine,
>but shifting either from the small to the middle or from the middle down
>to the small chainring pretty much stopped working. With the derailleur
>set so that I could shift down to the small chainring, shifting back to
>the middle required an extra movement of the shifter beyond the middle
>setting. A setting that would allow shifting up to the 32-tooth
>chainring meant that I couldn't shift back to the 22-tooth one. The
>derailleur would move, but the chain would hang on the middle chainring.
>A very competent LBS suggested that the new 32-tooth chainring might not
>be appropriate for the crankset, so I bought one (part # Y1FU98020) that
>is specifically for the FC-M580 crank. Still very poor shifting. I
>could find an adjustment so that it sort of works: shifting from the
>middle to the small chainring usually works as long as I pause, shift,
>and then move the pedals. Shifting back up to the middle usually works
>if I shift while moving the pedals without hesitation. Neither works
>every time, whereas earlier it would have worked every time without any
>conscious thought.
>
>Is this fixable? Thanks for any suggestions or advice.
>
>I like this bike because it fits me and because it's like an old friend
>that has accompanied me to so many out-of-the-way places (for example
>here: https://flic.kr/p/a7w3LM ), but now am wondering whether it might
>be time to give up.
>
>
>
>Regards,
>Ned


I've had similar problems, but in my case it was the adjustment of the
front derailer that was the problem. Shimano says that the derailer
cage must be parallel with the chain wheel with ~1 - 2mm clearance.

try
https://www.google.co.th/search?q=how+to+adjust+shimano+front+3+speed+derai ler&ie=utf-8&oe=utf-8&gws_rd=cr&ei=xpWAVvWJMMyvuQSU37GYCg#q=shimano+instructions+f or+front+3+speed+derailleur+adjustment
which is a PDF from Shimano or

http://www.instructables.com/id/How-To-Properly-Adjust-The-Front-Derailleur-On-You/
which is a little less formal.

Another thing to check is the clearance of the inner plate of the
derailer and the middle chain ring.

The other things are, of course, the inner and outer stop screws and
the cable both of which the Shimano PDF cover.

As a sort of general statement I mix Shimano derailer's and chain
rings with no problems so far (knock on wood). My current "Bangkok
Bike" has a new Shimano 105 front shifter with a Sugino 50/42 chain
rings, from maybe 30 years ago, and friction shifters and it shifts
perfectly well.
--
cheers,

John B.

[Ned Mantei[_2_]]

On 28-12-15 03:10, John B. wrote:
> I've had similar problems, but in my case it was the adjustment of the
> front derailer that was the problem. Shimano says that the derailer
> cage must be parallel with the chain wheel with ~1 - 2mm clearance.

I had adjusted the derailleur not too long ago, and the shifting was
fine before I replaced the chainrings. Unless I somehow managed to bend
the derailleur somewhere along the way while installing the chainrings?
I will check again.

Ned

[John B.[_6_]]

On Mon, 28 Dec 2015 11:56:32 +0100, Ned Mantei
> wrote:

>On 28-12-15 03:10, John B. wrote:
>> I've had similar problems, but in my case it was the adjustment of the
>> front derailer that was the problem. Shimano says that the derailer
>> cage must be parallel with the chain wheel with ~1 - 2mm clearance.
>
>I had adjusted the derailleur not too long ago, and the shifting was
>fine before I replaced the chainrings. Unless I somehow managed to bend
>the derailleur somewhere along the way while installing the chainrings?
>I will check again.
>
>Ned

If the number of chain ring teeth changes, i.e., the diameter, one may
have to relocate the derailer to match the new diameter.
--
cheers,

John B.