Campy FD question—Paging O.P.

[echelon_john]

Hi all,
I was helping another forumite build a bike up for his wife last night, and was stymied by the front derailleur. It's a 650c road bike by a well-respected builder, with a 28.6 st. Drivetrain and derailleurs are Campy Record 10 triple. Crankset is 30/39/53. Chain is Campy. Rear der is a long cage. Cassette is 11/25.

2 issues, possibly (but not necessarily) related:

1. When the FD is positioned high enough that it clears the outer chainring vertically when shifted outboard, the bottom rear of the derailleur rubs the chain when in the small chainring and anything smaller than the 18. I realize the triple in this case is kind of a 'bailout' setup where you're not going to want to be in the 30/15, but the fact that there's so little vertical leeway seems odd. It's definitely a triple FD, which was my first thought. My second thought is that given that it's a small framed, 650c bike, the ST angle is likely fairly steep. So if it's, say, a 75 degree seat angle, would that couple of degrees steeper than 'normal' rotate the front derailleur clockwise enough to bring the rear end of it up to a point where it rubs? If so, I'm inclined to rig some kind of a spacer/shim that kicks the back end of it down by a few mm.

2. When adjusted so that it shifts down to the small chainring at all, it requires more than one full throw through the range of the lever to get it to upshift onto the middle chainring, then requires trimming back down to stop it from rubbing on the inside. I'm not a big Campy guy, but have never encountered this. If adjusted so that it upshifts nicely with a full throw of the lever, it then won't downshift back onto the little chainring. Shifting from the middle to the large and back seems ok.

We tried canting the derailleur in and out slightly to see if tweaking that helped, at least with the shifting part of the problem. Didn't seem to.

So I guess my questions are:
- Do you think the steep ST angle is an issue here, and should shimming be my first corrective step?
- Any known issues/anomalies with this setup?
- Since we can run another FD easily since it's Campy, would that be the simplest solution?
- What else am I missing?

Thanks for any light you can shine on this.
JC

[thwart]

Can't speak to the specifics here, but I've set up two 650c bikes for my wife and daughter, both with a Campy compact drivetrain, and had no issues compared to other builds I've done.

So… I'd discount the seat tube angle issue.

But then again, those weren't triples...

[oliver1850]

Let's see the FD.

On my bike the chain clears the cage bridge at the rear by 1/4" when in the 30/12 combination. I can't imagine that STA would make that much difference, but perhaps BB height could. If BB is relatively high compared to axle C/L that could run you out of clearance.

Is the 30 really needed? Perhaps given the 650c wheels, you could go up to a 32 or 34 small ring.

It takes 4 clicks of the left lever to shift from the 30 to the 42 on my bike. I have the QS (Escape) levers.

[oldpotatoe]

Hi all,
I was helping another forumite build a bike up for his wife last night, and was stymied by the front derailleur. It's a 650c road bike by a well-respected builder, with a 28.6 st. Drivetrain and derailleurs are Campy Record 10 triple. Crankset is 30/39/53. Chain is Campy. Rear der is a long cage. Cassette is 11/25.

2 issues, possibly (but not necessarily) related:

1. When the FD is positioned high enough that it clears the outer chainring vertically when shifted outboard, the bottom rear of the derailleur rubs the chain when in the small chainring and anything smaller than the 18. I realize the triple in this case is kind of a 'bailout' setup where you're not going to want to be in the 30/15, but the fact that there's so little vertical leeway seems odd. It's definitely a triple FD, which was my first thought. My second thought is that given that it's a small framed, 650c bike, the ST angle is likely fairly steep. So if it's, say, a 75 degree seat angle, would that couple of degrees steeper than 'normal' rotate the front derailleur clockwise enough to bring the rear end of it up to a point where it rubs? If so, I'm inclined to rig some kind of a spacer/shim that kicks the back end of it down by a few mm.

2. When adjusted so that it shifts down to the small chainring at all, it requires more than one full throw through the range of the lever to get it to upshift onto the middle chainring, then requires trimming back down to stop it from rubbing on the inside. I'm not a big Campy guy, but have never encountered this. If adjusted so that it upshifts nicely with a full throw of the lever, it then won't downshift back onto the little chainring. Shifting from the middle to the large and back seems ok.

We tried canting the derailleur in and out slightly to see if tweaking that helped, at least with the shifting part of the problem. Didn't seem to.

So I guess my questions are:
- Do you think the steep ST angle is an issue here, and should shimming be my first corrective step?
- Any known issues/anomalies with this setup?
- Since we can run another FD easily since it's Campy, would that be the simplest solution?
- What else am I missing?

Thanks for any light you can shine on this.
JC

No doubt about it, the steepness is why the chain drags.

As for the shift off the small ring, then trimming, a lot has to do with the ST angle and what part of the fder the chain hits.

ALSO 10s Record was 53/42/30 so the 'bulge' on the FD, meant to move the chain from the middle ring to the big, is higher, above the 39t, PLUS higher still because of the ST angle. Probably get better shifting to the 53 with a 42t middle.

Only shim or bend the der hanger if the chain doesn't follow the arc of the chainring.

Another thing that comes to mind..is the 39t a true middle ring? With pins and such? Or a double installed on a triple? If the later, shifting up to it will take more FD movement, more 'clicks'.

[Ralph]

This may not be helpful......but just as a reference. And on a 700C 56 CM square steel frame with 28.6 seat tube. Probably 73 degree angles.

I run 2004 Record Triple cranks on this bike. 30-42-53 (or 52 sometimes) with either Centaur Power Shift or Centaur Ultrasdhift....both new hood design levers.

The FD is positioned about 1.5 CM above chainring. The rear of the FD almost touches the top of the ring. The inner cage is parallel with small ring. I usually set it up try to run about whole cassette on any chainring without trimming. Usually get 9 of 10 and all on big ring.

With adjustable derailleur cable stops, and FD cable about as tight as it can be without moving the FD, little ring to middle ring takes 3 clicks, middle to large ring takes 2 clicks. Down shift is simple push of the button. This is pretty much so no matter if I use the Power Shift or Ultra Shift shifters. Only difference between the two is how you trim it.

Somehow you've got to get the FD to clear the chainring, align the inner FD cage with small ring, and get the FD cable really tight. Maybe use a cassette starting with a larger cog and larger cogs all the way. I use 12-30, 13-29, 13-26 or 14-23 with mine. Chain clears the FD bridge about a 1/4".

[oliver1850]

While a steeper STA definitely makes the chain drag problem worse, I don't think it's the only contributing factor. At the 3.25" distance that the back of the cage is behind the seat tube centerline, a 2 degree change in STA only moves the back of the cage about .1" vertically. I'm reasonably sure a Campagnolo triple can be set up to work on a normal 700c bike with a 75 degree STA.

Regardless of the whys there are some things that would help:

Shim the FD angle as you mentioned.

Bigger small ring and/or cogs.

You should have the 12 click left lever if it's Record 10. That lever will shift any front derailleur. I'd look for another FD that has more curvature to the cage so that the bridge is lower, maybe a MTB FD. I've got lots of FDs here and could probably come up with one that has a lower bridge than a Campagnolo triple.