If you are ordering a bike that will be shipped to you, then be sure to follow their instructions for assembly. If there are conflicts between what they say and what you believe, then call their support line.

If the bike is from a shop that assembled it, then take it back to them for any immediate needs. Typically they do that work for free. And it was probably their mistake in the first place. Which they should see so it can be addressed. Whether it's the mechanic slapping himself or the owner refraining from slapping the mechanic. <grin>