Any issues with sticking a big seatpack on there for the occasional lightweight mini road trip?

Seemed fine when we did NC500 earlier this year

Seemed fine when I did NC500 earlier this year too. Carbon frame and carbon seatpost with the large Apidura saddle pack

Good enough for me. Out of interest, how many days did you do the NC500 over?

4 days self-supported, but I added on the better bits skirting the West coast (such as Baelach na Baand and Inverpolly) and returned down the middle from Tongue rather than the rubbish-for-cyclists North-East and East coast

It’ll be fine. I’m slightly paranoid so put some helicopter tape around the parts of the post it touches but bar that, you’ll be fine.

I did jamiep route too…we self supported over 7 days…was ace!