Front derailleur head scratcher...

So been messing with the front derailleur and can't solve this problem.

When running small to big the derailleur won't shift far enough towards to frame to allow the chain to run smoothly without rubbing.

Limit screw is all but removed, even with the cable completely slack, and it looks like it's setup in the right place to me. I've had it setup on another frame fine. All I can think is, the mount is too far from the frame, or the rear dropouts aren't aligned and are throwing the chainline out... No tools to check for that quickly.

Here are some pictures I took quickly.

Bent cage? Alternatively, could you try rotating the whole derailleur slightly to move the back of the cage inward (assuming that it's currently running correctly parallel with the chainring)? It's a horrible fix, but might be worth a shot.

Is anything new on there or is that how it came?

Looks as though the derailleur is hitting the frame.

I had a similar problem on a Quintana Roo frame and used spacers on the drive side BB cup and a small one behind the cassette to kick everything out a little. Still had enough thread in the respective areas to ensure everything tightened up.

If you remove the cable where does the mech sit. Will it run on the small chainring then??

No cable and it still catches, def not hitting the frame and has tons of room, and pretty sure the cage isn't bent as it was working like a dream on the last frame I had it on.

As for moving it so the cage is pointing inwards at the back of the cage, the hanger kinna forces it into the right position... Which is annoyingly unhelpful in this case.

Hence the head scratching...

Sounds like a BB spacer on the drive side would be a good fix then.

In what gear does it rub and how many gears do you have?

Running Shimano 6600 all over, so 10 speed, and it's when I'm in the lowest gear, small front big back.

Not had experience with BB spacers, will they work with a hollowtech thingy?

Inside chain ring look close to the chain stay to me, maybe it's a triple front mech, not sure. Cheers

Odd tho, as it's worked fine on the last frame I set it up on. And the model number is correct for a double.

Cheers tho, appreciate all the input.

measure the distance from seat tube centerline to center of derailleur mount bolt to see if that differs from your old frame.
my old rossin has about 27mm

It's not a triple. BB spacers are simple. They fit on the drive side between the cup and the frame.

I wouldn't space much more than 3mm as you need enough crank spindle on the non drive side to catch and tighten the crank arm onto. Can also add a 1mm spacer behind the cassette.

I realise all this affects q factor and chainline but you don't have many options.

I'll look into the spacers and give that a try, doesn't need to be much I don't think as the derailleur isn't changing the chains path, just rubbing.

I'm wondering if I might be-able to machine a hanger that allows the derailleur to sit closer to the frame?

It's an old Look KG 221, so it has an attachment. I'll see if I can get a spare and mess about with it.

Give it a good clean with some degreaser/white spirit. Make sure all the pivots are thoroughly clean. Can you push it any further toward the frame by hand?

Is the BB spindle (axle) long enough? If it's an after-market fitting it might be too short; not used hollow-tech myself but it's ceertainly a possibility with other types of BB.

I can't move it further, cleaned and re-lubed everything before putting it together. The bottom bracket and cranks kinna go hand in hand, and are from the same groupset and model number. As I said, worked fine on the last frame I had it set up on. Bizarre.

... Maybe it's just trying to make me toughen up and ride climbs higher up the block...

... Just to make sure I measured the width of the bottom bracket shell on the Look and the previous frame, both 68mm.

I'm gonna order some spacers and see how different it feels riding with them.

Plastic cassette spacers are a close fit. You may be able to pick some up FOC at a bike shop.

Would that kick the cassette out too far for the lockring to catch the threads?

The cassette spacer is to go between the frame and the BB. Depending on the speed of cassette they are mostly around 2-3 mm wide.

Ahhh I get you now. Found some on SJS, as I won't be riding anything steep(ish) till the weekend. Cheers.

You mentioned re trying to machine a spare derailleur hanger- I have one you can have for free if you want. Not a Look one though, but perhaps these things are pretty standard...

That would be really appreciated if you have! My boss at work is all ways claiming his machining skills, so I may put him to the test.

I'll pm you.

OK, think I have this solved, but not 100% happy with the fix.

Stuck a 2.5mm spacer on the driveside of the bottom bracket and can now shift perfectly into my lowest gear with no catching. I tried to put a 2.5mm spacer on the left hand side, but there isn't enough for the cap to catch the threads inside the cranks.

I'm just not sure how this will effect riding over distance, being slightly over to the right of the bike? Anyone had experience of this sort of thing?

... I guess I just need to do a decent length ride and test it...

I've emailed Look to see if they have any spare front derailleur hangers laying about I can try and machine into the right position, as that would be the prefect fix... Waiting on a reply.

I tried to put a 2.5mm spacer on the left hand side

That wouldn't make any difference would it? (if by "left" you mean non-drive side). The aim is to shift the drive-side BB cup (including spindle if it's a square/ISIS/Octalink BB) out a few mm and take the chainset with it. Putting the spacer on the non-drive side wouldn't achieve that.

I'm just not sure how this will effect riding over distance, being slightly over to the right of the bike? Anyone had experience of this sort of thing?

I've often wondered about this since I've measured the downtube-crank face distance on some of my bikes and it never comes up exactly the same on both side (NDS is usually wider). I suspect it won't make a huge difference though: think of all the other things that affect it like cleat placement on shoe and foot placement in shoe, not to mention biometric issues like unequal-length legs.