free wheel ?

[krebs]

I need to replace the free wheel on my bike. The old one is a MZ-Z012 shimano 5 speed. I've seen ones online that are labeled MZ-Z012 but are 6 speed. Can I replace my 5 speed with a 6 speed? I'd like to have an additional low gear if it will fit. Thanks.

 

[Sharky]

Googling, I believe the width of the six speed is 33mm. How does this compare to your five speed?

 

[Sharky]

Do you have the removal tool for a DIY job?
Might not be much of a cost difference at your LBS, if you have to buy tools and will save a lot of huffing and puffing and bad language as you try and remove the old one.

Don't forget to replace the chain at the same time.

 

[Ian H]

I seem to recall that 'compact' sixes were a straight replacement for fives in the days of friction levers.

 

[Ajax Bay]

Yes a 6sp freewheel will screw on to your hub as a direct replacement. Assume a 126mm OLD (over locknut distance).
Before procuring a new freewheel block, ensure that you can physically remove your MZ-Z012. Often a complete bar steward.
If not, see @Sharky advice.
You'll find a 14-28t easily (eg Halfrauds) but any larger sprocket more difficult/expensive. Be sure your rear derailleur, if old, has the capacity to cope. 28t: no problem, but more than that may require B screw antics.