Braze on height

I've just fitted a modern group to my early 90's steel frame, and the front derailleur braze on seems too high for the compact crankset. I'm seeing something like 5-6mm clearance above the chainring teeth when the derailleur is at the bottom of the braze on adjustment range.

It still shifts, but I'm wondering if anyone has experience with a similar problem? Can you get some sort of extension for the braze on?

Your frame was made for 52/42 and before compact chainsets were commonplace, hence the gap.

No idea of how you would get around this without 53/39 and a dash of HTFU... :)

I have a bike with a similar setup. I think you have to realise that when you mate an old frame with new parts, or vice versa, there will be some compromise. If it still shifts then probably better to leave it alone.

Other solutions include;

• filing the bottom of hanger slot to let the mech sit lower
  
• use a band-on mech clamped just below the hanger
  
• get a mech with a different shape cage. I found a triple front mech that did the job.
  

Yeah I think if I'd thought of this before ordering the groupset I'd have probably just hardened up and got a 53/39 crank - but now I've spent the money on the parts I'd rather just use what I have.

Shame there's no magic extension part I can fit, but as you say, it works well enough (occasionally throws the chain over the outside, but not enough to be a big deal) so I'll probably just have to make do.

Cheers

The problem with an extension is making it stiff enough to resist twisting when shifting.

Filing the slot would buy you a couple of mm, provided the clamp still fully mates with the braze-on, otherwise you'll likely have the same problem as with an extension.

FD are cheap enough so Yoav's suggestion of using a triple is worth a punt, or possibly one of the newer FD that can handle both compact and standard rings, eg Campag from 2009 onwards.