A dry creak. One that sounds like nails running down a chalkboard, and takes weeks to find…
That one especially. My seatpost/saddle currently doing this to me so I’ve narrowed it down. Entirely wrecked last night’s excursion. Not even a mouse-squeak but a loudish crack-crack-crack. In fact am just about to tackle it, trying lithium grease on the post and some GT85 into the saddle-guts. Sitting pedalling on it sounds like it’s about to snap, which is (I hope) far less likely than it sounds, even allowing for post-seasonal loading (currently rated ‘biffer’)
Any noise on a bike (other than swishing of tyres and smooth ‘tk-chk’ of a gear change) drives me insane. I also have Hope hubs and not from a sense of masochism, they just came with the bike. May have to sell/swap 😬