Last year I switched the drivetrain on my Scott CX Comp from 46/36 to 50/34 rings. It went fairly well but I do tend to get a bit of noise on the 3 small sprockets when on the small ring. Ok, I can avoid that, but it is annoying having it happen on the 2nd and 3rd smallest sprockets. Trying to compensate for this by adjusting the FD makes the largest 3 sprockets when in the big ring noisy. Once more, that is a bit of a pain.

So, I was wondering how much difference there would be between the FD-CX70 and FD-4600 derailleurs? Images make have them looking pretty similar, but I dod wonder if there was a slightly different shaped cage on the 4600 that would better suit the 50/34 rings?

The cassette is 11-32 10 speed.

And, if anyone wants to suggest an alternative to the FD-4600, I'd consider that.

Are you trimming the FD while in the noisy combinations?

Looking at the tech specs for both, they appear to be identical RE: ring sizes/tooth count difference/seat tube angle.

You might actually have better luck with a FDER designed for 1-2 fewer "speeds" if you have one in the parts bin to try.
I use a Tourney on my 9 speed triple "aberrations" and they work reasonably well for 22-32-36/38 combos.
It's a different ball of wax, but I had more rub with a 9 speed RDER.

The CX70 has a different shaped cage that is better optimized for a smaller large ring (46T), but otherwise is identical to the FD-4600 in function (assuming you have the bottom pull version). However that shouldn't affect the function of the FD when you're in the small ring at all, so I would be willing to bet that a better adjustment of the derailleur is needed. I assume you had to move it up the frame when you put on a big ring? Make sure the FD cage is correctly aligned.

Yes, I have but have never found it to be that great. particularly since chnaging the rings. It did work reasonably well with the 46/36 rings, but now there is not much trim in it. And it is a devil to set up. If I remember right, I can ow only get it on the large ring.

Thanks, I dont have a spare so it would be a purchase.

You will be right with that. What I have set up now is a compromise to let me achieve as little noise but this does mean some noise on both rings. However, if I was to properly set it up, I may be able to eliminate the noise on one ring but more on the other.

I did move the derailleur up the frame a bit and tried to make sure that the cage was parallel with the big ring. Measured the height from the teeth, etc.

If I am right, the images I have seen of the the cages seems to suggest that the 4600 is slightly less curved and maybe a little longer than the CX70?

Alignment is pretty critical, almost all the problems I've had in the past with FD rubbing have been fixed by adjusting the FD correctly.

I own a CX70 and previously ran a FD-5700 (105 version of the 4600, essentially the same), and that is correct.

You are looking at this the wrong way. A FD is not the solution. However, there are plenty of people who deeply believe that throwing money at an issue would solve it (new FD), and you may be one of them...

With your gearing you have no business using the large chainring with the 2 largest cogs, nor using the granny with the 2 smallest cogs. Such cross-chaining results in mechanical losses and premature wear.
Even with a larger chainring differential you still won't need to use the cross-chaining combinations. It may be your habit to use these, but it is unnecessary as you have a very similar gear ratio by using the other c/ring.

On one of my bikes I have been riding a 46/28 (and lately a 46/26) double with a 11-36 10-speed cassette for many thousands of miles. Shimano 105 SIS shifters, CX70 in the front and a XT RD. A good adjustment of the FD makes it possible that trimming is necessary only when using the granny with the 3rd smallest cog, and the large c/ring - with the 2nd largest cog (which in my case is absolutely necessary with the 46/26 in front). All other gears are noiseless without trimming.

Your comment that the trimming now only works in the large ring and is "devil to set up" tells me that your adjustments are amiss. On the other hand, I have a considerable experience with such adjustments, having wrenched on bikes for some 49 years...
So, there you have it: either re-learn how to shift and what combos to use, or learn to live with the noise. Replacing the FD won't solve your problem.

This. I use a Di2 9070 FD with a 46/30 crankset (square-taper LOL) with an 11-32 and it doesn't make noise. The Di2 roadie FDs were never made with anything lower than 50/34 in mind.

OP, this sounds exactly like an alignment and placing issue of the FD. SO long as you don't have a riveted/etc. FD braze, you should be able to get the FD to the place it needs to be to do what it needs to without noise.

Thanks, but I disagree with you. I agree that you should not try to use big/biggest or small/smallest but not so much that 3 sprockets are excluded from use on either rings.

Furthermore, when I bought the bike from a very reputable dealer, they explained that the trim function worked only on the large ring. Now I think they may have been wrong with that but it does at least prove that they too had problems setting up the trim finction on the bike. I can achive trim on both rings, but the movement is so slight as to make it ineffective on both rings. Therefore, I opt to set it adequately on one and not the other.

And I do know how to shift using various permutations.

Thanks for the response.

Thanks, is that a Shimano FD? I'll check it out.

I'll check the set up again. But I have spent considerable time on this when chainging the chainrings. I even downloaded the dealer's manual for the derailleur and have tried to make sure that alignement, clearance, tension, etc is all right. However, since the opinion sems to be that a more suitable derailleur does not exist, then I will persevere.