10 speed chainset, 9 speed everything else. What chain works better?

[nandystam]

So rather than excess straining and swearing, I've gone an ordered a 10 speed chainset (Tiagra 4700) since 9 speeds seem a rarity now. The old crank was also Hollowtech II so shouldn't be any issues with fitment.

Given the rest of the bike is still a 9 speed setup (Sora), what chain is preferable? It seems that either a 9 or 10 speed chain would work, although shifting might be less than ideal with a 10 speed? The more you read the more unclear it becomes

What chain would be preferable to use in this case?

Thanks

[Duck!]

Always match the chain to the cassette. The crank is nowhere near as fussy.

And neither the Tiagra or whatever (but presumably Sora) crank was in before is Hollowtech II. Two-piece yes, but the arms are solid. Hollowtech, either 1st or 2nd gen, only applies to 105 & above.

[nandystam]

Thanks. I'm sure I've seen them marketed as Hollowtech II, maybe they just mean from compatibility perspective.

The only other question I have, from reading the online instructions, the exploded diagram shows a spacer between the non drive side crank and the BB cup. It then suggests it's required for a triple chainset, but mine is a double. I've read doubles don't need the spacer, but not really sure? I don't recall seeing a spacer when taking off the old chainset (also a double)

[Duck!]

Yup, triples have a longer spindle due to fitting the third ring on. As such, there's a spacer on each side which are not present with a double.

[nandystam]

Thanks. Look forward to putting it all together, successfully, I hope