What am I missing?

[BruceBanner1983]

They aren't necessary, but they are nice to have to tension the chain.

I had a motorcycle that I had trouble getting the chain tensioned and aligned properly, so I found tools to help me. One tool tightens the chain to set the slack, and another sits on the sprocket with a rod that runs parallel to the chain so you can see the chain alignment. It makes it dead simple and takes all the guesswork out. The motorcycle had the axle chain tensioners but I still couldn’t get it right until I used those tools. I will also be using those tools on my MB.