There were a handful of undermount clamps made for Pros when the bike was launched, but those didn't go into production.
Anyone you see with undermount clamps now has either modified the standard clamp or had something made. I suspect Alistair Brownlee has the standard clamps with the wing cut off to achieve his undermount position.

They actually make a specific part for that, and it's available (in stock) at the moment.

That's not an undermount specific part. It's the TT bracket for narrow above bar positions and has the advantage of not needing to cut off the wing. Obviously that is what Alistair and others have used.

It’s just the part they use. You can tell because when they use the drop bar, the extensions are angled the same as the angle of the base bar. But technically you’re right, not a part specifically for that purpose... there isn’t one.

Can you post the link to where I can purchase this part?

Thank you.


Bilal

If you DM me your email I can send you an invoice for it. We have it.

Dm sent

That's cool! I already have the TT clamps bought but had no time to install it.