Hi

Hope someone can help me with this one please, and apologies in advance, as the explanation is going to be ***** as I don't know the technical name for the parts??

While giving my 2018 Expert Carbon rear wheel and cassette a good clean, the (I don't even know the technical term for it) hub axle (??) screw-in thingy fell off (see pic) (EDIT: END CAP) on the brake disc side . I have no idea how tight it's supposed to be, if you just nip it up by hand, or you need a spanner on it, so any advice would be welcome. All I can assume is that if it fell off, it was never tight in the first place and explains why the axle bolt never looked fully home on the bike.

What I will say is, and why I'm asking how tight it should be, is when I nip it up by hand and put the wheel back on the bike the free hub doesn't sound like it did before this happened. It doesn't sound as "clicky" ?? This makes me think I've over tightened it, and it should be more loose. And when I put the wheel back on the bike and tighten the through axle, there seems to be a bit of friction slowing the wheel more quickly than you would think it should. The wheel is an Axis Expert, and I can't find any info on Youtube or the net on how to service it.

Any advice and correct naming of parts would be warmly welcomed

Cheers,
Graeme.