avhed

Looked at my freewheel this week and noticed a varying space between gears. Does anyone know what they are? The Suntours gaps are well known but what are Shimanos? Is no one knows, I would be like to know how wide the 2 slide on sections of the freewheel body are?

pastorbobnlnh 

The best picture I have of a MF-7400 body is below. The three largest sprockets fit on the larger lower portion of the body, while the 3rd and 2nd sprockets fit on the smaller diameter portion of the body. The smallest sprocket is threaded



The spacing is the same between the sprockets, it does not vary, and is the same for 6 speed UG cassettes.



If your spacing is variable, my guess is that someone mixed up 6 speed spacers with 7 speed spacers. I believe you can find the thickness of the spacers on Sheldon Brown's website.


(600 and DA sprockets and spacers are interchangeable)

dddd

Every 7s freewheel or cassette that Shimano has ever sold uses 3.1mm spacers except in the 2-3 position (between the 2nd and 3rd-smallest cogs).

The 2-3 spacer measures 3.3mm. This was done to improve shifting to the smallest cogs (where the derailer's "chain gap" to the cogs was larger and where the return spring's force was lower).

On freewheels, the 2-3 spacer is usually built onto the 2nd-smallest cog.

The 3.3m spacer needs to be in the correct position for use with indexed shifters, and the freewheel's asymmetry doesn't allow the use of a reverse-action "Rapid-Rise" derailer unless the 3.3mm spacer is first moved to the other end of a 7s cassette.

Suntour's asymmetry followed (very roughly) the same strategy, though in their case the spacers between the largest few cogs were made thinner.