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Old 02-19-11, 07:37 AM   #1
DubT
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Front derailleur suggestion

We have a 1989 Santana Visa, and I want to replace the front derailler. The shifters are 8 speed/triple Ultegra bar ends and the rear derailleur is a new Ultegra. The bike is currently using an old Suntour front derailleur.

What would suggest?

Thanks in advance, Wayne
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Old 02-20-11, 09:47 PM   #2
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Is there anything wrong with your old Suntour?
Why not an Ultegra to match the rear?

One thing to watch: Modern triple front changers are more "three-dimensional" than old ones from the 1980s, to make them index more reliably with STI-type systems. Because of this, they have pre-conceived ideas about how much smaller the middle ring is supposed to be compared to the big one. (On our set-up, a 42T middle ring fits but a 44T ring scrapes against the lower edge of the inner cage when the chain is on the 53T outer ring, no matter how the cage is trimmed.) So even if you are not using the indexing functionality with your bar-ends, you are constrained by the current indexing standards in your choice of FDs. The 32/48(+/-)/53 "half-step-plus-granny" arrangement that was popular on touring bikes with 5- and 6- speed freewheels in the early 1980s will not work with modern FDs. But if your current middle and big rings respect the current conventions you should be fine with pretty much anything. (Our Santana is the same vintage as yours and it came with 32/42/53 so I'll bet you'll be OK unless you got carried away tinkering with your transmission.)
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Old 02-21-11, 07:34 AM   #3
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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. There aren't many good quality, new 8-speed models available. As mentioned above, also pay attention to the middle-big tooth difference that the FD is designed for, because this is important with modern triple FDs.

If there's not much wrong with the current FD, then I would try to stick with it.
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Old 02-21-11, 08:43 AM   #4
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Originally Posted by Chris_W View Post
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.
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Old 02-21-11, 07:00 PM   #5
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I think that I will stay with the old Suntour, my problem was shifting to the 28t, no problem 42-56 or 56-42. I had to learn to make sure we did not have any pressure on the chain when I made the shift. We have been riding some fairly decent hills in Hot Spring Village. A new experience for flat landers.
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