Used to be Conspiratemus
Join Date: Jan 2009
Location: Hamilton ON Canada
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Originally Posted by Chris_W
New front derailleurs designed for 9 or 10 speed chains may be too narrow for your 8-speed chain, causing chain rub in many combinations. ...
If there's not much wrong with the current FD, then I would try to stick with it.
You should be able to micro-trim that out with your friction-mode bar-end shifter. If not, you could use a 9-speed chain. Possibly
the narrower chain might not lift as slickly going from smaller to larger rings but that concern applies mostly when you are relying on indexing to make the shift -- that's where the ramps and pins on the chainrings really help. But if you are using friction shifting you can finesse it by hand just as well. I find plain old-fashioned smooth chainrings shift just as well as ramped and pinned when using downtube friction shifters.
A chain that is a tiny bit too wide can catch its rivet ends on the pins of the inner face of the outer chainring when it is on the middle ring and the smallest rear cogs, particularly if there is a large tooth difference between the two. But if this was going to happen, it would already be happening with your current setup since this has nothing to do with the front derailer.
That said, modern front triple derailers are designed to work with indexed shifting and that capability is what you are paying for. With non-indexed shifting you can get good performance with a cheap and cheerful FD as long as it is robust enough to take the twisting abuse that a FD gets subjected to.
An old Suntour would have to be pretty worn and sloppy before I would change it to something else.