Freewheel hub wiggling in place + Chain tension?

[Steven Cheung]

I purchased a used single speed and for some reason the pedals seem to move while the wheels are going even in the free wheel mode. (They only rotate forward slowly while wheels are spinning, I can easily hold them in place with no resistance and they will not spin backwards). Additionally I bought a new chain as I believe this is an old model and likely needs a chain replacement but I'm not sure if I should try to size my new chain to the current one. I have heard about the 1/2 inch movement but after attempting to tighten the chain it feels like the chain is still loose.

Video of pedals moving with wheel + chain wiggle: https://imgur.com/a/bkJnC2M

I also noticed that the freewheel hub itself appears to wiggle in place while the wheels are moving, is this a problem? How would I go about fixing this?

Video of free hub spinning: https://imgur.com/a/9jWsoxX


Thank you!

[mtnbikeracer76]

The reason your cranks are moving is that the pawls inside the freewheel are sticking, not allowing the freewheel to rotate freely.

The movement in the freewheel is just some lateral play that is found in inexpensive freewheels. Better freewheels like the ones from Shimano don't wobble as much.