Originally Posted by sivat

The measurement means that the spindle is 103mm long. The chainline is the distance from the center of the frame to the center of the chainring. 42 is standard for track, but 45 isn't a problem. Plus, you can't find a bb shorter than 103mm. There is a small chance the ring could hit the chainstays, but unless the bike is made for wide tires or fenders, it shouldn't be a problem. Even if the bike is made for wider tires, you shouldn't have any problem with a 42t chainring. If you go to a 46 or 47, you may have some issues depending on the frame. both of my recent conversions easily fit a 48t chainring ( a crosscheck and an old japanese-made road frame) but I had issues with an old Bianchi strada touring/city style bike with anything bigger than 44t.