Ultegra di2 front derailleur clamp compatibility?

[theStig]

Does the FD require a di2 specific clamp? Are there any lightweight alternatives that would fit?

Would the DA di2 clamp fit? what's the difference?

thanks in advance!

[Dammit]

I used a lightweight carbon clamp with my 7970 front mech and after a while noticed that it was flexing significantly during a shift- had a good look and found that the carbon fibre was cracking from the force being applied during a shift.

I replaced it with the Shimano DA clamp, which has stiffened the front shift up significantly.

Given the amount of violence that the motor applies to the front mech with an electronic groupset I'd prioritise strength over weight for that part, then save some weight by cutting off the battery cover and mounting the battery in the seatpost.