Actually, the pictures that Trump's offices have released of the "bikers for Trump" are a number of years old and are from a completely unrelated event.

But if you want some idea of how many people are actually going to attend all you have to do is look at the number of buses that are scheduled to arrive.

For Obama's inauguration over 3,000.  For Trump's a total of 200 (and at least some of those are protesters).  For the Women's march 1,200.

Moreover the scalpers are losing their shirts - they literally cannot give tickets to events away (even on white supremacist websites) and, if you need another sign of Trump's desperation he's released a video giving free tickets to anyone that asks.