What age/height could your kid handle a 20 inch bike?

[SkyBlue1987]

My boy has just turned 5, about 115cm tall and is growing out of his 14 inch bike. His legs are slightly bent when seat at highest setting. I will take him to bike shop in weekend to have a look but I looked at some 20 inch bikes recently and they seemed so huge. Not sure if it’s worth getting a 16 inch in the meantime, he has a younger brother to pass the bike down to so not too worried about the cost.

Frame size is more important than wheel size for a good bike fit, specifically seat post length and reach.
Are his legs slightly bent when sitting on the seat touching the ground or when touching the pedal?
Also consider how much he uses his bike, what he uses it for, and how far he rides it.
115 seems huge for a 5 year old, might he grow into the 20" wheeled bike quickly?