Out of curiosity, what would cause it to walk up?
It squishes the top of the seattube so that's a smaller diameter and the clamp will slide up towards that smaller diameter.
Tester will put it in more technical language.
Not sure about that, but the principle is the same as stem clamps on steerers and I've explained that in non technical language more than once on here.
@gbj_tester started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
It squishes the top of the seattube so that's a smaller diameter and the clamp will slide up towards that smaller diameter.
Tester will put it in more technical language.