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 chain stay 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.
Trying to figure out why it does this, I took the back wheel off the bike and noticed that coastering was sooo difficult. Basically the freewheel was not moving counter-clockwise as it should, if for a lot of effort pushing it.
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 vise 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.
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.
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 :).