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Old 07-16-10, 08:32 PM   #1
kh6idf
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Front derailleurthat actually works?

I have decided the crappy Shimano front derailleur on my Marin Fairfax will never work properly. I found out the shifter was broken (after only 9 months) and replaced both shifters. But the front derailleur will never shift properly to all 3 chainrings without rubbing on one side or another on at least one of the chainrings.

Does anyone make a front derailleur that will actually work with a triple chainring with no rubbing and does not require constant adjustment to stay that way?
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Old 07-16-10, 08:35 PM   #2
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First question, and apologies if you already know this, but are you expecting your front derailler to have no rub in all of the rear gears? Because the range is different for each front ring (i.e. you can't be on the big ring in front and the big ring in back.)
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Old 07-16-10, 08:54 PM   #3
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No, I'm not expecting it to cover all the gears in back for all 3 front rings. But on the middle front ring I should be able to use most of the rear gears. I just don't seem to get a normal range of gears (larger half on the back with smallest front ring and smaller half on the back with largest front ring) without it either rubbing or going too far or not far enough. It's almost like the shifter and derailleur are incompatible (but they're not). I had a lot less trouble before index shifters. If it rubbed I could just move the shift lever a little to stop it.

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Old 07-16-10, 09:48 PM   #4
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Index shifters can be a pain. When you adjust it, are you turning the limit screws on the derailleur itself? If you are, are you turning them more than a half turn at a time? Sorry to pepper you with basics, but I don't know how much you know.

It is possible to have a cheap FD that doesn't rub...Well, I have two that work, perhaps I'm one of the lucky ones.
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Old 07-16-10, 09:58 PM   #5
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I would take it to a bike shop to fix for the first time. It's not too expensive overall and once it's done, the front derailluer takes a long while before it goes out of adjustment. Google front derailluer repair and there are a couple of videos on this very subject.
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Old 07-17-10, 03:47 AM   #6
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Quote:
Originally Posted by kh6idf View Post
I have decided the crappy Shimano front derailleur on my Marin Fairfax will never work properly. I found out the shifter was broken (after only 9 months) and replaced both shifters. But the front derailleur will never shift properly to all 3 chainrings without rubbing on one side or another on at least one of the chainrings.

Does anyone make a front derailleur that will actually work with a triple chainring with no rubbing and does not require constant adjustment to stay that way?
SR Suntour, makes a great d´┐Żrailleur for the front, in the middle chain ring,( number 2 ), no chain rub through
all the gears, if your trying something like 1 and 7 , that will not work...( stupid anyway)..but you sound like you already know that...Richard
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Old 07-17-10, 04:07 AM   #7
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Both Shimano and SRAM make front mechs that don't rub. If they do, there's a fault and it can be caused any number of problems from bent chainrings to faulty alignment or stiff chain links. Shimano's cheapset FD, the Alivio, will give buttery-smooth silent front shifts when set up properly, with no rubbing.

If there's wear or deformation on the chainring ramps; that can cause 'rubbing' symptoms as users try and adjust it out in order to regain smooth shifitng. If as you say, you have 'constant adjustment' then you have constant wear.

If any of your drive train is worn, and it will be if the bike gets regular use, then no amount of adjustment will fix that.

Re 'index shifters are more trouble.' If you got wear, you got trouble. The only way you can be sure is to replace the chainrings and front mech. Index shifting is flawless when it is not worn.

If you had a faulty index shifter, then you almost certainly will have resultant wear on the FD plates and chainring ramps.

Replace the FD first, and if you still have problems, replace the chainwheel/crankset, and chain/cassette. If you have the FD rubbing or noise from the FD plates, and you can't calibrate it out with a turn or two of the barrel adjuster on the cable, then you have wear or mis-alignment, or both.

FD mechs, chain rings, chains, guide wheels, tension wheels and rear cassettes are all consumable items.

If you start replacing any of this, check the bottom bracket and cranks for play first. If you just a have slightly bent chainwheel it can be moderately de-bent in a vice with care. Otherwise, new FD and chainwheels, chain and cassette will fix it.

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Old 07-17-10, 07:55 AM   #8
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The Shimano 105 components on my Fuji work very well. It has a triple chainring and ten rear cogs. There is no rubbing except when trying to run big ring and 2-3 biggest cogs. There is a trim position on the front shifter that will allow you eliminate that however and you can run forever that way if you wish. Check your shifter instructions, on mine you give the downshift trigger on the front a half click to get the trim position. There is only one limitation on doing that, you are somewhat likely to jump the chain off front, back, or both if you pedal backwards while cross chained like that. It has happened to me once so far although I have certainly backpedaled in that situation many times.

Ken
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Old 07-17-10, 08:10 AM   #9
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Thanks for the advice - I've had it to the shop twice, and attempted to adjust it per the online video at bicycle tutor. The shifter is good since it was just replaced.

UPDATE: Well I took it to the shop today and they managed to adjust it to where it works OK now. Took quite a while but they finally got it. One thing I learned is you don't use the barrel adjuster to center the derailleur cage on the chain, you do that by adjusting the limit stop screws (at least while on the largest and smallest front chainring), being careful to not go too far. They said the barrel adjuster was just to take up any slack in the cable if it stretches.

I went out and test rode it several times until I was convinced we had it right but it does everything I want now. On the middle front ring it will start rubbing as I get into the lower half of the gears but when I hear that it's a reminder to shift up to the large front chainring and it actually will cover ALL of the rear gears on that ring without rubbing now.

Last edited by kh6idf; 07-17-10 at 12:16 PM.
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Old 07-17-10, 06:07 PM   #10
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Or a Shimano FD-R453.
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Old 07-18-10, 05:16 AM   #11
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Apparently your bike has an FD-R453 ... I have an FD-R443 and it works like a charm.
The problem is probably not the derailleur itself, as it is a quality component, but rather the cables or more likely the exact set-up.
Setting up a front derailleur is tricky and needs very precise allignment to be able to do all the gears.
I have an SRAM attack gripshift and it has 9 clicks for the front derailleur instead of 3 clicks on most shifters ... this is very handy for "trimming" the front derailleur to get into awkward gearcombo's when needed.
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Old 07-18-10, 08:29 AM   #12
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9 clicks would be great - almost as good as the old pre-index shifters that had an infinite number of clicks!

I have it adjusted now so it works well in all the gear combinations I actually use. But yes, it's a series of very precise and sensitive adjustments that are inter-related. One thing that helped was finding a set of instructions from Shimano that came with my shifters. Once I figured out the hi and low limit screws were actually reversed on my particular derailleur things started making more sense. I got to one point where it was pretty close but the chain would skip the middle chainring when downshifting off the largest one. The instructions said if it does this to turn hi limit screw 1/8 turn (either tighten or loosen, I forget now)'. I did this and like magic it fixed the problem.
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