Just got a Cateye velo 5. Nice basic computer. Its all set up...but i have 2 questions. One where should the sensor be on the spoke? The pictures look like about 3/4 of the way up the spoke...closest to the wheel. Is this correct?

also my tire size is not on the chart....and the chart seems fishy.

Cateye chart says....

47-406 20x1.75=152cm

47-406 20x1-3/8=162cm

Mine is a 37-406 20x1.35=And it came out to exactly 150.5 cm when i measured it myeslf. How come my tire width is the smalles out of these but has the smallest circumference. The smallest out of the 2 listed above.....has the BIGGEST circumference. Does it have to do with the model or brand of the tire? note mine is a 37-406...whatever that means.

For my first ride i just used the standard "20 inch" setting. However i got home and entered as close to the exact amount as possible. I entered 150 cm...as there is no room for decimals. Should i stick with the 150 cm that i input?