> I dunno about elsewhere but in Ontario the legality of a bike being on a sidewalk is based on wheel diameter to permit kids bicycles.

There is no Ontario-wide law, per the Highway Traffic Act, §185(2):

> (2) The council of a municipality may by by-law prohibit pedestrians or the use of motor assisted bicycles, bicycles, wheelchairs or animals on any highway or portion of a highway under its jurisdiction. R.S.O. 1990, c. H.8, s. 185 (2).

* https://www.ontario.ca/laws/statute/90h08#BK286

London:

> 2.12 Motor vehicle - bicycle - on sidewalk - exceptions No person shall, without lawful authority, either by himself or by permitting others, operate a motor vehicle or bicycle along a sidewalk. This section shall not apply to a person who, […] or (d) being under the age of 14, operates a bicycle along a sidewalk.

* https://www.trekbicyclestorelondon.com/about/cycling-law-lon...

Toronto:

> Chapter 950-201 C(2) of the Toronto Municipal Code states that “no person age 14 and older shall ride a bicycle on a sidewalk of any highway.”

* https://www.toronto.ca/services-payments/streets-parking-tra...

Nothing about diameter/radius.