There’s a good chance I’m being thick here but I’ve just read the Trek review on the home page which states that the 148mm hub spacing allows for shorter chain stays. I can’t visualise how this makes a difference, could somebody please explain?

The wider the hub, the more material to chop up, thus a longer ‘saw is needed.

It’s purely down to Pythagoras; A hypotenuse of fixed length with an increasing opposite length leads to a shorter adjacent length…by the tiniest margin…

It’s all to do with trunk diameter.

Just means more chain to sharpen.
Do you need kevlar trousers to ride treks now?

You bought the wrong chain.

Oh darn it, check before sending. Thank you Daffy, that makes sense (must be a pretty small difference).

It’s not the hub per se, it’s moving the chainline out by 3mm that does it.

So the chainring is further out of the way and the tyre can move in, got it cheers.