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Old 07-11-09, 11:06 PM   #1
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indexed front derailleurs

I'm back into fixing bikes after a many-year hiatus.

One thing I still don't get is indexed front derailleurs. Chain angle changes when you shift in the rear, and you need to tweak the front derailleur. But you can't. Huh?

Also, to get the front derailleur right for one chainring, it's wrong for one or two other chainrings. On my new bike (which I just built with Ultegra 9-speed stuff), the chain rubs the front derailleur on the left side when it's on the smallest (of three) chainring. If I adjust to eliminate that, then it will rub on the outside when it's on the largest chainring. In other words, the distances between the chainrings need tweaking, but I don't believe it's possible.

Please help.

Thanks.
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Old 07-11-09, 11:16 PM   #2
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Don't cross-chain. It sounds like you're using a triple. If you're in the smallest chainring, you should only be using the 4 or 5 largest cogs in the rear. You should DEFINITELY not be in the smallest cog in the rear. If you're trying to do this, then of course no matter what adjustments you make to fix one, you will undo any adjustments for the other.

If you want to be able to use more cogs in the rear with just a single chain ring, use the middle chain ring. This on will allow you to use pretty much all of the rear cogs without rubbing (though you might experience some unless you set your limits right in the sweet spot for the middle chainring)
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Old 07-11-09, 11:29 PM   #3
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tom,

you are correct. indexing for left shifters is absolutely stupid. im a trimming nut. i love to have my derailleur in the best sport for every shift.

as iareconfuse said, try to tune everything for the middle ring or whatever ring you are going to use the most.
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Old 07-11-09, 11:46 PM   #4
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iareConfusE, I don't cross chain, and I don't know why you think I might.

illwafer, I did optimize for the largest chainring, and I suppose that is my folly, but I don't want any rubbing when in largest chainring and smallest (highest) sprocket. That's why my chain rubs the LEFT side of the front derailleur cage when using my smallest chainring and LARGEST (lowest) sprocket.

And yes, it's a triple chainring crankset.

And thank you for agreeing that indexing on the left it stupid. I feel validated!
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Old 07-12-09, 04:45 AM   #5
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You can trim an indexed front derailleur. They are designed to do just that.
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Old 07-12-09, 05:18 AM   #6
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iareConfusE, I don't cross chain, and I don't know why you think I might.

illwafer, I did optimize for the largest chainring, and I suppose that is my folly, but I don't want any rubbing when in largest chainring and smallest (highest) sprocket. That's why my chain rubs the LEFT side of the front derailleur cage when using my smallest chainring and LARGEST (lowest) sprocket.

And yes, it's a triple chainring crankset.

And thank you for agreeing that indexing on the left it stupid. I feel validated!
Sounds like the front derailleur could need more room to the left. Did you already try to set the limiting screw of the front derailleur for more action to the left? Eventually loosen the cable a bit to allow the derailleur the full movement till the stop. If that all does not help I guess your BB axle is too short, which leads to an incorrect chain line. The chainrings would then be too close to the frame for the front derailleur to work correctly In this case it cannot move further or even hits the seat tube in full left position.
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Old 07-12-09, 08:36 AM   #7
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Originally Posted by vettefrc2000 View Post
You can trim an indexed front derailleur. They are designed to do just that.
That will be good to know if I learn how. Can you describe how?
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Old 07-12-09, 08:38 AM   #8
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wasabi, thank you. I did build this bike up from a mixture of old and new components, so the BB could be too short.

It's a Surly Cross Check. The drive chain is 10 years old, from another bike.

I'll try the various suggestions above.
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Old 07-12-09, 10:17 AM   #9
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+1 here's another vote against indexed FDs.

The benefits of the ability to trim for varying chainlines far outweigh the benefits of index front.

Unlike RDs which have only one perfect trim for any particular cog, FDs need to accomodate varying chain angles. Also being free to trim allows more aggressive shifting, with the final position trimmed back afterwards.
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Old 07-12-09, 10:25 AM   #10
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You can trim an indexed front derailleur. They are designed to do just that.
Some front shifters can trim the FD, but others can't.
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Old 07-12-09, 10:38 AM   #11
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campagnolo 2009 is indexed, but it has 3 clicks to get from one ring to another, allowing for a lot of trim.
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Old 07-12-09, 10:48 AM   #12
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Yeah, I don't know about the bar end shifters but even low-end Tiagra brifters have trim positions for the front derailleur. But regardless of shifter used, the OP should be able to adjust the derailleur to eliminate the problems he is mentioning, by changing the cable tension and adjusting limit screws.
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Old 07-12-09, 11:49 AM   #13
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Try this:
http://www.youtube.com/watch?v=ngm6dr-1na0

Have triple myself, and this tutorial worked great. I'll be trying to install brifters soon, so I'll see if that tutorial works for them as well.
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Old 07-12-09, 04:53 PM   #14
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Is the front derailleur a 9-speed? If you have a 10-speed FD that could be the problem.
Shimano road triple compatible shifters have 4 main positions plus a trim position for the inside ring. This means that there are two positions that can be used for each of the 3 chainrings.

Al
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Old 07-12-09, 06:42 PM   #15
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I only use gripshifters, but I'll chime in to note that the left shifters come in two versions, "indexed" and "micro-shift". The latter give you 3 or 4 stops between gears so you can do relatively fine adjustments. I find that when using the middle ring up front and the 3-4 smallest gears in the cassette, I need to trim the left shifter up a notch to avoid chain rub on the FD.
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Old 07-12-09, 07:03 PM   #16
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This is a 9-speed setup. The wheels, crankset, derailleurs, and brifters were all working perfectly on the previous bike they lived on. I will look to see if the left brifter has a micro-shift mode. I'd love to find it, if it exists.

Basically, the problem is that there are three positions for the left brifter, and they are all too close together. The low setting doesn't go low enough, and the high one doesn't go high enough. Setting the limit screws, as described by the video that u2chin cited, doesn't seem to help. Cable travel is inadequate, and that seems to be the brifter's fault, not the adjustments on the derailleur.

And this is true not just on this bike. I see it on a lot of bikes, and I figure I need to know some trick, but I haven't found it yet.
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Old 07-12-09, 07:12 PM   #17
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Tom

There's no doubt that for some odd reason, Shimano chose to have very limited adjustability on their front shifters, as compared to Campy road, as well as compared to older style friction shifters, that had unlimited trim ability thru the range (I have no experience with SRAM). Shimano seemingly chose the route of making the shifting as simple as possible, but then exercised tight control over the tolerances of bottom bracket length and crank design.

Thus any odd combination's of equipment - I.E. crank and b-bracket, that are outside of Shimano spec's, tend to make the front shifts a huge problem to get to work reliably and well with Shimano shifters. In my experiences, setting up a non-spec'd system is a royal PITA.

One solution for road systems is to use Campy shifters, whose front shifter has many more trim/click points and as a result, much better trim adjustability.

I have been relatively happy for 6 years now, with Centaur shifters with anybodies front derailers and cranks, with a Centaur R derailer shifting a Shimano 9 spd cogset on a wheel with a Shimano hub. One trick to this is to place an 8spd Shimano cassette spacer in the middle of the cassette, to account for the slight spacing differences between Campy and Shimano.

Is the shifting as perfect as a well tuned Shimano 9 or 10 spd. system ?, no, it's not. But it's tolerable.

One issue that forced me down this road was when I moved to a Lemond titanium frame that was significantly less stiff in the bottom bracket then the Klein's I had ridden prior. I experienced a lot of derailer rub when standing (I'm a Clydesdale), that was outside the ability of the Ultegra shifters to compensate for. Thus the move to Campy Centaur shifter, which solved the rub problem.

Steve B.
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Old 07-12-09, 07:48 PM   #18
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Quote:
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Basically, the problem is that there are three positions for the left brifter,
Nope. If you have 9-speed Ultegra shifters there are 4 main positions plus one trim position on the left shifter. This gives you two positions for each of the 3 chainrings.

Be sure that the left shifter is in the lowest position before setting the low limit screw and before attaching the cable. Per instructions, flip the small shift lever several times and remove any slack from the cable before attaching the cable to the derailleur. The first position is simply all of the cable out.

Follow the instructions for setting up and adjusting shifters and derailleurs found at: http://www.parktool.com

Your derailleurs are not indexed. The indexing is in the shifters.

Al

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Old 07-12-09, 08:18 PM   #19
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I only use gripshifters, but I'll chime in to note that the left shifters come in two versions, "indexed" and "micro-shift". The latter give you 3 or 4 stops between gears so you can do relatively fine adjustments. I find that when using the middle ring up front and the 3-4 smallest gears in the cassette, I need to trim the left shifter up a notch to avoid chain rub on the FD.
never encountered a microshift shimano left shifter.

as far as I know, it's a campagnolo feature on 2005 centaur, 2005/6/7/8/9 chorus/record, 2009 veloce/centaur/athena shifters.
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Old 07-12-09, 08:42 PM   #20
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I think I'll go hunt up a way to change my shifter for the FD into the weirdest friction-shifter I can come up with. Thanks for the incentive all.
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Old 07-12-09, 10:23 PM   #21
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never encountered a microshift shimano left shifter.
Sorry, I should have specified that I was talking about SRAM gripshifters.
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Old 07-13-09, 05:35 AM   #22
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On my Frankenbike, I use downtube friction shifting on my bike with a 10sp Chorus crank on a Zeus bottom bracket, although not a triple, and 10sp Ultegra rear cassette and old Campy NR derailleurs. It shifts beautifully and is dead silent. No chain rub in any combo because I can trim it.
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Old 07-13-09, 10:09 AM   #23
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Lightningguy, thank you very much. It's hard to get information of the type I seek, because my perspective is odd. I was a super expert of the most minute details until 1984, then I practically fell of the face of the earth. I'm back now, and I can figure out MOST of the newer stuff, but it's knowledge like yours that fills the gaps.

I am not going to change my equipment, because I don't want to spend the money. This is the first pair of brifters I've owned. It's great to have brifters, because I can shift at times I otherwise wouldn't bother, because it's not worth the trouble to reach for a traditional shifter. But the price of brifters is daunting. $200 for the very cheapest pair. Plus, it's not possible to repair them if they start malfunctioning. (Right?) Still, what you say is helpful and encouraging.

Al1943, I do realize that indexing is in the shifters, not the derailleurs. I will try your suggestion.
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Old 07-13-09, 12:47 PM   #24
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Campy shifters are rebuilable and the parts are cheap, but Shimano aren't really rebuildable (giving them a flush with tri-flow or something is about all you can do).
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Old 07-13-09, 08:11 PM   #25
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Campy shifters are rebuilable and the parts are cheap, but Shimano aren't really rebuildable (giving them a flush with tri-flow or something is about all you can do).
In my experience, Campy shifters, while I love them dearly and are re-buildable, are very expensive to get parts for, as well as a PITA, depending on the shop and how good their connection is with the US supplier of Campy parts. I have heard horror stories from other Campy aficionados.

That said, I have 2 sets of Centaur shifters with 6 years of use and they keep on humming, but then, so does my Shimano stuff.

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