I’ve had an issue with my tri bike this week, where the rivet holding the front derailleur cable guide popped out of the frame. My LBS is hopefully going to re-rivet it, and hopefully it’ll all be fine. However . . . .
. . . it got me thinking as to what to do in the event of a mid-race front derailleur failure! Is it simple a case of removing the cable, and adjusting one of the limit screws to set it permanently in the big ring?
That should get you home, yes.
The classic MTB fix (from back when people ran 2 or 3 rings up front) was, if you can’t tie the remains of the cable to some that would work, was to put a suitable stick between the seattube and cage to wedge the cage in place.
Thanks! I’ll read up on FD limit screws - just in case!!
It’s just a matter of adjusting the low limit screw to drive the mech into the desired position.
Realistically by the time you do that your race is over anyway…so getting home in the 34/36/39 is as good as getting home in the 50/52/53 so why even stop 
In a long race it wouldn’t be any worse time-wise than a puncture I assume?
Better than a puncture anyway.
I had assumed road race where getting back to the group would be challenging. Over a full distance bike leg then it wouldn’t be so bad I suppose.