My bike came with a 25.4mm pipe type post, brazed on clamp & quick release about 5 years ago. Few months ago I got a micro adjust 25.4mm post & pitlock and this is when it started to slip even after applying 2 layers of coke can strips. Bike shop measured seat tube and sold me a 25.8mm post & that started to slip too! I over tightened the pitlock skewer to the point that it broke in the middle!! However when I clamp on with the QR it doesnít slip. For security reasons I donít want to stick with the QR. Any suggestions besides having to buy yet another post?
Well, it sounds like the 25.8 fits, and that when clamped tight enough (with the q/r) it doesn't slip. You should be able to use a non-q/r clamp and get it as tight as with the q/r clamp. What's limiting you from tightening the allen-bolt more? Maybe you could resolve this by getting a new clamp?