I have recently moved from the land of flat to an area with many hills. Because of this uphill has become more difficlut and I am thinking of changing from a MF TZ21 14-28t to a TZ500 14-34t on my 7 speed cruiser. What would I need to do this and will I have to change the chain? Thats for helping an old man!

You need to make sure your rear derrailluer can handle a max 34T (manufacturers list it in the specs), and yes, you'll need a chain 6 links longer, assuming your current chain is the correct length for the gearing you have now. And you'll need the freewheel removal tool in the link below.

https://www.amazon.com/Park-Tool-Fre.../dp/B001B6RGXG

Because you are putting a new freewheel on,
is a good enough reason to replace the chain too..

even if you were putting an unworn replacement of the same ,
is a good reason for a new chain.

and because worn chains cause faster wear on the freewheel (or cassette ) teeth ,
don't leave a chain on too long.

The new chain will probably be closer to 2 or 3 half links longer (wraps halfway around the freewheel).

So, probably closer to 1 or 2 full double links longer than what you have.

As [MENTION=197614]fietsbob[/MENTION] mentioned, a new chain is a good idea when replacing your cassette anyway.

You'll need the freewheel removal tool, likely the FR-1 from Park Tool. Check this to make sure before ordering.

Do you have a bench vise?

Many thanks to everyone. I did go to the Shimano dealer manual for the derailleur on my bike and it will take up to an 11-36T. And after reading what it entails I think a trip to the local bike shop is probably worth the extra cost.involved.

Don't worry about how many teeth your derailleur can reach, just get a drop mount for it. They cost like 3 dollars from china, and drop your derailleur an inch, so even a 30t max can handle a 36t freewheel. I have one on mine.