I am new to mountain biking and I recently bought a used old steel-frame mountain bike for commuting/off road used. I am about 5ft4, the bike frame size is 16 inch, and it fits quite well on me. But the only part I feel uncomfortable is the bike stem, it seems way too long for me, so I am planning to get another stem to replace the current one. So what size of stem should I be getting if I want a better fits? Thanks in advance.