3-8 speed chain works ok with 10 speed derailleur

[GuyBoden]

An old decathlon 3-8 speed chain works ok with my 10 speed Shimano derailleur.

It doesn't rub on the RD cage or the FD cage.

Interesting or is this common knowledge?

Obviously, all multi speed chains have the same inner roller width.

 

[Ajax Bay]

You may not realise but the 6-8sp chain (let's leave out "3-8" - that's taking marketing advantage of the fact that a narrower chain will work) is rubbing on the two adjacent sprockets and this may (will) adversely affect shifting precision particularly where there is only one tooth difference.
10sp sprocket pitch = 3.95mm, so between teeth of 3 = 7.9mm. Gap ('air') between is 7.9 - two half sprocket widths (1.6) so = 6.3mm.
The 6-8sp chain (say KMC) is 7.3mm wide (outer). A 10sp chain is 6.2-5.88mm (latter dim is for narrow directional chain).
I'm sure the chain "works OK".
Inner width: 5-8sp chains have inner width of 3/32″ (2.38 mm) and 9-12 speeds have inner width of 11/128″ (2.18 mm).
HTH

 

[GuyBoden]

You may not realise but the 6-8sp chain (let's leave out "3-8" - that's taking marketing advantage of the fact that a narrower chain will work) is rubbing on the two adjacent sprockets and this may (will) adversely affect shifting precision particularly where there is only one tooth difference.
10sp sprocket pitch = 3.95mm, so between teeth of 3 = 7.9mm. Gap ('air') between is 7.9 - two half sprocket widths (1.6) so = 6.3mm.
The 6-8sp chain (say KMC) is 7.3mm wide (outer). A 10sp chain is 6.2-5.88mm (latter dim is for narrow directional chain).
I'm sure the chain "works OK".
Inner width: from 5-8 have inner width of 3/32″ (2.38 mm) and 9-12 speeds have inner width of 11/128″ (2.18 mm).
HTH

Many thanks for a very good explanation.