Was out on my old Sequoia for the first ride of spring the other day. I've got 650B wheels on the frame, moustache bars, and a 75mm stem (bike originally had an 80mm I think). The steering is really twitchy. My question: is the twitchiness from A) the smaller wheel size (bike is from mid 80's so probably had 700c wheels) B) the smaller stem size C) both of those things or something else entirely? I've never had this issue w/ any other bike. Thanks!