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Dura Ace triple/chain line questions(9 posts)

Dura Ace triple/chain line questionseflayer
Feb 10, 2003 7:31 PM
Two shops have not been able to get my triple front deraileur to operate properly. By all indications the rear part of the chainline at the cassette is a tad too far inward and causes the chain to derail when on middle chain ring in front and largest and next to largest cog in rear. Has anyone ever adjusted chainling by somehow putting a spacer behind the cassette to bring it out a mm? Is this even doable? Someone said if you use an aluminum spacer it would fatigue under load and not work properly. Any input, opinions, experience appreciated. This is a ti frame and perhaps hard or impossible to align.
re: Dura Ace triple/chain line questionsShultzman
Feb 11, 2003 3:20 AM
I've struggled with the same DA Triple front der. shifting problems on my Trek OCLV. My LBS has tried three times to fix the problem, but it's very hard to duplicate on the work stand. I've played with vertical adjustment and cable tension, and have finally gotten it to where I can live with it. Hardly what you'd expect from DA.

I was able to adjust out the problem you are having, but mine consistently shifts past the middle ring into the granny when shifting from the big ring, unless you are in the lower half of the rear cassette.

I've been told the adjustment on the front der. is finicky, but I don't know if it is chainline related.

Let me know if you find a solution.

trek/dura ace tripleeflayer
Feb 11, 2003 5:24 AM
If you go to yahoo and type in "trek suicide" up will come a result from, I think, If once on that site you type the same thing into that searh box, up will come a discussion about trek and triples. Not necessarily exactly the same thing, but a suggestion on how to fix with chain ring spacers. Good luck. The hard part of this is that this kit worked perfectly on two other of my frames.
re: Dura Ace triple/chain line questionsKeeponTrekkin
Feb 11, 2003 6:13 AM
A few regulars on this board use a downtube shifter for the front der (as does LA, I believe); it's simpler and lighter. I don't recall, but presume they are used in friction mode as your problem is basically rooted in index shifting.

re: Dura Ace triple/chain line questionsMR_GRUMPY
Feb 11, 2003 7:38 AM
Chainline problems like this are usually caused by the frame. Was your frame designed for a triple? or was it designed for a double. The down side of Shimano's splined bottom bracket is that you can't order a shorter size. Shimano used to make square bottom brackets in many different sizes. If someone had a problem like yours, they could always get a shorter BB.
I have some really really bad news for you :<bludoggy
Feb 12, 2003 5:41 PM
I am currently awaiting my third trek 5500 frame. My first one did EXACTLY what you are talking about. It was the worst on climbs. I would stand up and then, ugh, my chain would drop off of the middle chainring. It took some time to convince my LBS that there was a problem with the bike. They kept trying to tell me that I needed to adjust the front der., but it in fact had nothing to do with the der, but rather with a horrid chainline caused by a messed up bottom bracket.

To make a long story short, the trek rep finally got involved, he has admitted finally that many of these frames had the BB shell threads inserted incorrectly (carefull measurement confirms this) and so they sent me a new frame. Same problem, so now they are sending me a third frame which is a new 2003 model (with free 500 dollar paint upgrade, i might add). The rep assures me that this frame will be correct.

If you want more details on how to do the measurements, or what to say to your dealer to convince them, or even the name and number of my lbs, let me know. Be sure to deal with this, because absolutely no amount of tweaking or adjusting will fix it. Let me know how it goes..
Steve Dally
sorry, above message was for schultzman. nm.bludoggy
Feb 12, 2003 7:00 PM
I have some really really bad news for you :<Shultzman
Feb 13, 2003 4:40 AM

Thanks for the info.

If you could give me your dealer's phone number; I'll have my dealer get in touch with them, and get the necessary info on measuring and how to approach Trek about this problem.

Thanks again,

re: Dura Ace triple/chain line questionseflayer
Feb 13, 2003 5:38 AM
My frame is not a Trek. Someone has suggested that even if frame is not aligned to exact spec, you can change chainline a bit with an xtr 116 mm bottom bracket. It is not only shorter by a hair, but also slightly adjustable because it comes with spacers to make it work on a 68 mm or a 73 mm bottom bracket. That range also suggests you could use other additional small spacers to adjust chain line. I will first install a new chain and then will try bb replacement.