Well, one of the problems I noticed with the Miyata One Hundred is that when coasting the chain was sagging a lot, touching the chain-stay and sometimes even the spokes.
That is both dangerous, ugly and is making the chainstay very dirty. And less efficient, since when I start pedalling again there is half a second until the chain get straight again and the pedals are rotating the wheel. Also, this might be one of the reasons why the chain was falling off the small chain-ring quite often.

freewheel Shimano MF Z012 6 speed
Dirty freewheel on Miyata One Hundred
This freewheel is full of grease and mud. I tried cleaning the cogs before but the freewheel is not moving smoothly, as it should.

Trying to figure out why it does this, I took the back wheel off the bike and noticed that coasteering was sooo difficult. Basically the freewheel was not moving counter-clockwise as it should, if for a lot of effort pushing it.
The first step was to take the freewheel of the hub and this proved to be pretty difficult. For the Shimano MF Z012 freewheel of the Miyata One Hundred one needs a freewheel removal tool, like the Park FR 1. I was lucky enough that the only freewheel puller tool I have matches the hub.

Amazingly enough (!) I don’t have a vice in my apartment, so I had to use a 24 mm open wrench to remove it. Pushing down with the foot, while keeping a firm hold on the wheel did help, but I’m now looking for a 24 mm box wrench, as this reduces the risk of damaging the freewheel extractor tool, by gripping on all six its sides, not only two as the open-wrench does.
Afterwards, I tried to figure out how to clean the freewheel, a video on YouTube is recommending WD-40, however, I preferred to dip the entire freewheel into diesel and let it there for one day.

Cleaning the freewheel in diesel
Cleaning the freewheel in diesel

After that I washed it with water, let it dry and cleaned the teeth a little bit more. Now it looks much better, but also I can see some damage to the teeth.

Cleaned freewheel
Cleaned freewheel


Shimano MF Z012
Shimano MF Z012 freewheel

That is not a big problem until I need to replace the chain as the chain and the sprockets now know each other pretty well :).

10 thoughts on “Cleaning the freewheel Shimano MF Z012 14-28”

  1. Hey dude! You have any more pics of that cassette? That first pic is good (but dirty), i’m trying to build mine back together but I have lots of different parts and i’m unfamiliar what are the original ones! I see you have a quick lock but I got an old fashioned one.. What parts are after that spacer I can see a little bit in the first pic?

    1. Hello man,

      sorry for the late answer, I was just reviewing the posts and noticed your comment!
      I will check for more pictures, if you still need them. Or I can just try to snap few more. Did you manage to put it back together in the meantime ?

    1. You’re right, Stephen! Normally when changing the sprocket one should change the chain as well. And the opposite. But is not easy to find original components anymore!

  2. Well, just finding your post from 3 years ago, but I have a surplus MF-Z012, yours for the asking (and postage),

    1. Wow, it took me another three years and some self-isolation at home to notice the comments on this page. Thank you for the comment, Nick! Do you still have the MF-Z012? Where do you live?

  3. Old grease and oil? Dawn dish soap. It’s what they use to deal with clean birds and animals after crud oil spills. Totally safe, oil point just peals off

    1. That can work also. But I remember I tried once, diluted with water, and it was not really removing all old grease. But I can try again, doesn’t cost much to try and I have plenty of pieces with old grease on them, from other bikes!

  4. Hey all, you wouldn’t happen to know what size ball bearing I need for this freehub? Embarrassingly enough, I seem to lost one of them…
    I believe there should be 9 of them per side?

    1. Hi Rand, and sorry for the late answer. Unfortunately, I don’t know the exact size. Maybe someone else here can help?
      I think, yes, there are 9 of them, as far as I can remember. Somebody please confirm!

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