Hello,
I have a Nishiki Tri-A frame built with modern components and my handlebar rotates forward when I put more weight on tops.
It happened recently when I found a snow/ice patch on a trail and found myself balancing and to get through, but walked most of the parts .
And recently when I climbed some standing up.
I can loosen and tight back to the position I want, but this keeps happening few times now.
The size of quill stem and handlebar are for 25.4mm, so it is not an unmatched size issue.
Any suggestion/opinions are welcome.