Hello,

Forgive me, I had never worked on a bike until a couple of weeks ago when I bought a new-used Mercier road bike. The fork was dented and I swapped it out at a DIY bike place. They had only one fork that had the 27" wheel and enough length to fit the front tube. The advice I was given was to take it! I was lucky to find anything that fit! What they did not tell me was that new forks come long and can be cut down to fit. Nor did they tell me that some forks take different sized stems...

Skip over several hours of clumsy, frustrating work and the fork is now installed with the headset from my old CCM road bike (no longer ridable due to an ovalized front tube on the frame). The stem from my old road bike does not fit (the stem from the Mercier had to be cut as it was rusted into the fork). This is because the fork, though having the same outward diameter as the CCM fork (from which I got the headset), requires a 21.1mm stem. Eventually I found a shop with 21.1 stems and purchased one.

Yesterday was my second day of really riding the bike. This morning I went to take it to the corner and nearly fell off when the stem turned a different way than the front wheel.

My question is: are there different headsets for 21.1mm stems? Did the stem loosen because the headset cap is sized for a 22.2? The headset fits on the fork, but as I said, the outside diameter of the fork is the same as your standard fork that takes a 22.2 stem... do I need to find a new headset? Just a cap? Or did my stem loosen just because of the terrible condition of my city's roads?

Thanks a lot.