Derailleur Boss with Columbus MAX

[Clockwork]

How do you guys handle a front der. boss with a MAX tube? I had no problem filing a slant in the base to compensate for the flaring tube, but I'm having a hard time getting the tab 9mm ahead of the center plane.

Thanks, Joel

[Clockwork]

Mike Z. I'm looking in your direction.

[hampco]

we don't use the flared seat tube here, solves that problem. are you using a MAX BB shell?

[Clockwork]

Yes, it's a lugged frame.

[Jess Couch]

Don't use a cast tab and u can make it work.

[zank]

I have a Bringheli derailleur tab mounting jig. I use that as a guide. I had to modify the jig to make it work with the seat tube. Basically I grind and bend the braze-on to follow the shape of the tube as best as possible and get as close as I can to the optimal slot position. It's important to bring the tab slot in closer to the tube because if it sits too far outboard, you'll get rubbing in the small ring/big cog.

When I did a Di2 Max lugged bike, I actually made a tab to make sure I hit the marks because I didn't know how much flexibility the derailleur allowed.

Any way you look at it, it's a pain in the neck. And I do the same as Steve with the welded bikes. Regular round seat tubes.

[benson]

On the Max frame I made recently I chopped the boss in two, removed some material and brazed it back together.
Actually, I chopped three bosses and the third one was OK, but I am sure you can do better.
This is the first attempt: