There’s a bit of conflicting info here or maybe I’m misunderstand the dates - Credit cards have two critical dates: 1. billing dates (the cut off) and 2. a due date presumably 2-3 weeks later (called the grace period).

What is your billing/cut off date if your due date is April 13? Or is the billing date the 13th and the due date sometime later?

Your original post said:

$4500 CC bill payment due on April 13

Now you mention:

I get my statements on the 13th.

If you currently have a $1K balance .. presumably due on April 13 and you made a $3500 bike purchase AFTER the cut off date, that purchase will be on your statement due around May 13

Grab the last statement, send the billing date, due date, balance, and the date you made your bike purchase and I can give you a firm answer (and perhaps avoid interest altogether).

Cheers