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I have 2 spockets: front and rear. Front 52T, 110 BCD (Narrow wide tooth). Rear 18T,18T (34 mm/1.34'').

This is all information which I have. The front sprocket should be fine with KMC Z7, since, it was written, that it's compatible with 10-11 speed.

How can I check if KMC S7 can replace KMC S1 ?

Currently, KMC S1 is on the bicycle. But it seems to be too stretched.

If I have a few links of KMC Z7, can it help to ensure the proper fitting?

P.S. At the past it was a Dahon 6-speed folding bicycle, currently, I've replaced rear cassete with a single sprocket and the front ring after it was damaged.

Rear Sprocket Front Sprocket

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Single-speed chains such as the S1 have a nominal inner width of 1/8" while multiple speeds chains such as the Z7 have a nominal inner width of 3/32". So in theory, the Z7 should not be used, but in practice, it could depending on the rear sprocket teeth width.

You could measure the width of the teeth of your rear sprocket if you have access to a caliper or as you suggest, try directly with the Z7 and see if it meshes with the teeth without effort (no resistance).

Edit: I just saw on the KMC website that they also have single-speed chains with an inner width of 3/32" and 3/16", so those also exist. The difference with multi-speed chains with the same inner width would be that the single-speed ones may have thicker outer plates and no special grooves/ramps on the side to help with shifting.

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  • I've measured the width of rear sprocket tooth. The upper part has width of 3/32" and the middle/low part has a width of 1/8". Also I've measured the front chainring which has a narrow / wide tooth. The narrow tooth is close to 3/32" and the wide tooth is close to 1/8". So I'm a bit confused.
    – Michael D
    Apr 26, 2023 at 12:34
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    @MichaelD The width of a chain (e.g. 3/32") is the spacing between a pair of inner plates. The spacing between a pair of outer plates is larger so that is why the wide teeth of your narrow wide chainring are a bit larger. They will fill the gap and provide better chain retention. For the rear sprocket situation, sprocket teeth are usually a bit narrower on top, then enlarge. You need to make sure the inner link of your chain can engage sufficiently on the tooth. Since you measured 1/8" at the middle part of the tooth, chances are that your Z7 chain will not be large enough to fit well.
    – olliebulle
    Apr 26, 2023 at 13:20
  • @olliebule It makes sense. Thank you!
    – Michael D
    Apr 26, 2023 at 13:37

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