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Reading on every site about front dérailleur adjustment, the distance from the bottom of the outer dérailleur plate to the bigger crank cog should be "one penny".

park tool image, not mine

Mine is around 1cm! it does shift OK. not perfectly, i have to spin it very slowly and constant for the chain to move. but works. never dropped the chain or jammed.

The front dérailleur is a Shimano FD-MT60-AL, Deore (if you look at the pic here, it's showing a much closer distance, but it's also showing a rusty chain... so I will not mimic it right now :)

The crank is a biopace

Here's a pic of my bike. Since the crank is not round, i've set it up on the "closest" point to the derailleur distance from front deore dérailleur to biopace crank

Here's another pic. enter image description here

Another angle. There's no height adjustment, and there's no mark on the frame suggesting it ever was at another position. Can it be some lack of lube internally or bad cable messing things up? view of the derailleur adjustments

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1 Answer 1

up vote 2 down vote accepted

The bottom of the front cage on your front derailleur should be about 2mm higher than the chain ring, when the derailleur has no cable tension.

That is, when it is in the smallest front gear position.

On Bio-pace rings, that doesn't change. but it must be measured at the point when the chain ring comes closest to the derailleur cage. (The hardest part of your large ring.)

Some older derailleurs may have had different expectations. But not that I am aware of.

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...1-2mm over the biggest tooth - spin it a few times to make sure it doesn't hit on the other side, 180 degrees away. Also the outer cage flat area needs to be exactly parallel to the chainring for best results. Note that you cannot put a modern Shimano derailleur on there because the inner cage is not compatible with Biopace. Classic bike, b.t.w. –  ʍǝɥʇɐɯ Aug 4 '11 at 7:34
    
@zenbike with no cable tension, the derraileur goes all the way to the inner most cog. did I understood it right? –  gcb Aug 4 '11 at 17:39
    
@ʍǝɥʇɐɯ it is parallel alright i'm just worried about the height. I did follow all the other points on the park tool page, i'm just afraid to move the height w/out need and leave a nasty mark on the frame. Just finished restoring the bike with no prior knowledge :) –  gcb Aug 4 '11 at 17:43
    
@gcb: Yep. If you look at the height with it in that position, it should be 1-3mm, (ideally 2mm) above the large chain ring. The old school Deore that's in that picture sometimes were run high because the inside cage plate would rub on the middle chain ring when shifted on to the large ring position. If that is the case here, you will not be able to adjust it by the book. –  zenbike Aug 4 '11 at 17:50
    
thanks @zenbike. will lower it then. The back plate is way far away from the middle cog. I'm starting to guess that bike was used with a bigger front set before put the original back in. –  gcb Aug 4 '11 at 21:54

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