Originally Posted by
smd4
You should know by feel from the “gear you’re in right now” which gear you will need to be in to start from a stop, and shift accordingly.
^This^ Exactly this. You should just know...if you're going 15 you might need to downshift 1-2 cogs...if you're going 20 then maybe 3-4. You should be able to feel what's going on when you're riding your bike.