... my 17" bikes (MTB UK Raleigh) stem is not long enough, and I was going to switch it with another. I measured the I have and one is 22.5mm the other 21mm. I'm guessing that means that 22.5 is actually 22.2 (INCH STANDARD), whereas the 21 is actally 21.15 (bmx size)? Strange because the 21.15 bike is not a BMX, it's a 17" MTB UK Raleigh (1990's). Anyone know if older Raleigh's are likely to use 21.15 stems?