front mech too low in big and to high in granny!?
bluechair84
Posts: 4,352
This is a new one to me. When in the big ring the mech is only just clearing the teeth - the chain is being pressed againt the teeth when down shifting making for a less then perfect shift. But in the granny ring the mech is too high with the chain catching on the horizontal part of the chain, being lifted ever so slightly. Moving the mech high or lower to fix one ailment will only make the other issue worse. Don'e know the teeth range but it's a standard XT chainset...
Any recommendations? I can upload some pics later if that helps. cheers in advance.
Any recommendations? I can upload some pics later if that helps. cheers in advance.
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Comments
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bluechair84 wrote:This is a new one to me. When in the big ring the mech is only just clearing the teeth - the chain is being pressed againt the teeth when down shifting making for a less then perfect shift. But in the granny ring the mech is too high with the chain catching on the horizontal part of the chain, being lifted ever so slightly. Moving the mech high or lower to fix one ailment will only make the other issue worse. Don'e know the teeth range but it's a standard XT chainset...
Any recommendations? I can upload some pics later if that helps. cheers in advance.
Are they standard size chainrings. i.e.22 tooth,32 tooth and 44 tooth outer. If you don't know count the teeth on each ring.
Whats the Mech?0 -
bike and front mech are?"Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
*guesses*
either E-type mech that's rotated (actually I don't know how possible this is) or
ring difference too big or
2 ring front mech used (has a smaller cage)Everything in moderation ... except beer
Beer in moderation ... is a waste of beer
If riding an XC race bike is like touching the trail,
then riding a rigid singlespeed is like licking it
... or being punched by it, depending on the day0 -
The ring sizes were my guess, I haven't counted yet but i will when back home. Though it's a standard chainset - XT.
Frame is Ellsworth Moment, mech is Shim SLX, pretty certain it's the triple and not the double version though it's worth checking...0 -
bluechair84 wrote:But in the granny ring the mech is too high with the chain catching on the horizontal part of the cage, being lifted ever so slightly.
Edit0 -
Mech in granny ring, chain catches on horizontal of the cage - gear cable is slack;
Side view:
chain in big ring, shifter dropped to middle to show clearance when down shifting.
Any takers on how I solve the clearance issues? I followed the lining up guidance of that little orange flag when mounting the mech but it's not really high enough in the big ring, or low enough in the granny...0 -
Your images don't work.
What rear cog are you in when this happens with the granny?0 -
"Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
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thanks Nick - what had I done wrong? I usually get the links right :?
I'm middle on the cassette whilst shifting up and down the big to granny - I'd expect to be able to use the middle whilst in the in the granny... So you guys reckon too high? I'll have a play this afternoon and try get away with lowering the mech slightly. There isn't much spare room...
Thanks for lookin'0 -
take the chain off and make sure the mech is in the right place.
also check the part number on the mech as if it is a 2 ring version ................................"Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
Looks way too high!0
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i checked dropped the mech 2mm and it caught on the teeth of the big ring, i cant drop it much lower than it is. I checked the part number, its designed for a triple, it's definately not the stable-mate double ring mech (which i have on the ns). I'm very perplexed. I'll see if i can sort out a higher quality image to better show the clearence.0
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What frame is it? Sometimes chainstay angle can have an effect.0
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as it is a fully i would not be too worried as it will clear when you are sat on it. but a mech suited to a lower chain stay angle would be better,"Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
supersonic wrote:What frame is it? Sometimes chainstay angle can have an effect.
It's an Ellsworth Moment.
Nick - I hadn't thought about the sag affecting the clearence too. The remaining problem would be that the mech is so close to the teeth of the big ring, it doesn't down shift smoothly; I don't think the chain is lined up with the shifting ramps inside the cage. I'll move it up to where it shifts big to middle properly then try riding it in the granny, I might find both both rubbing issues solved... but it's not ideal for workshop fettling.
Can the angle of the seatpost make a great deal of difference? ie, if it was slacker, the bottom of the cage would be rotated further down giving me a greater amount of leeway. Are there different models that suit different mounting angles?0 -
Yes, the angles can make a difference - though a road type mech with angles to suit may accentuate the rubbing.0