I’ve noticed that on some of the new bikes I’ve been reading about that many require a boost rear hub while having a 73mm (or other non boost bb shell). Why’s that? I’d have thought the wider hub and standard BB would lead to more heal strikes on the chain stay.

Any ideas?

There isn’t a ‘boost’ bottom bracket as such, any offset comes in the cranks (or the chainring) although a lot of people are running normal non-boost chainline with no problem.

The reason boost is as wide as it is, at least according to trek, is that it’s as far as you can push the drivetrain out without having to push out pedals and increase the q factor. (The alternative view is that it’s in between two existing standards, but I leave that to your judgement/cynicism).

Thanks for the info.

Would full boost/boost crank give more room round the BB area for pivots and tubes and what have you? I’m assuming that the bikes I’ve been looking at (though without any plans to buy, the Hightower and Nicolai G13) have been designed around the non-boost crank. Why not take advantage of the extra potential space? It could be a backward compatibility thing, I suppose.

Of all the changes, this one grates me. Especially if it isn’t being fully embraced. Though I could have it all arse backwards.

A wider crank does give more room for a wider tyre (or you have some creative chainstay design). It’s only 3mm per side, but that can make some difference when trying to get a chain past a 3″ tyre.