Fast4 50

I was doing leg speed on the rollers this morning and was thinking about cadence goals/standards/handicaps by age and came up with this formula:

225 - racing age = cadence for your age

For example my racing age is 59 so 225 - 59 = 166. I hit 170 rpm so for this workout it was 102%.
I came up with 225 because 200rpm seems like a reasonable number that a 25 year old that isn't a freak of nature should be able to hit with training. Also it seems to hold with Junior riders that I race against on restricted gears. They seem to have no problem hitting 160-170 on the track.

Thoughts? Competing formulas or maybe you've read something somewhere. This is for fun, nothing scientific, just something to think about in between efforts on the rollers.