bike computer installation

it does, but I am still trying to wrap my head around it lol, but come to think of it no matter where it is one the post crosses the sensor at the same time no matter the where on the wheel the magnet is...hmm shoulda thought about that

Well, don't feel too bad about it. I had the same question, several days ago. The magnet and sensor on my mtn bike are ruffly at mid span of the spokes. Took me the longest time to figure out why it works....

Doug

As stated above, one rev is one rev.  Wheel size is important because the circumference of a bigger tire means more ground covered per that one rev.  Placement of magnet/sensor is more a function of where the closest point is on the fork between it and the wheel without getting up into brake territory.  The sensor and magnet have to be really close to each other or you won't get a reading.  Think of gap almost in terms of a sliver, just far enough not to touch.  FYI - Due to geometry of my bike, I have to add a shim between the sensor and frame when I'm riding a lot indoors and have to use rear wheel.  On the front wheel, you shouldn't have to do this.