I bought a cheap used road bike that has a square taper bb fitted (and cheap cranks). I’d like to upgrade the cranks to save a bit of weight and this would probably involve changing to a HT2 bb. It is simply a matter of removing the square taper bb and fitting the BB or could there be fitment issues?

It’s that simple.

There may well be cheaper ways of saving weight though, and HT2 is nowhere near as durable as ST.

Yeah, run the square taper until it wears out then change to an HT4 BB.

HT4????

Yep – by the time the ST one wears out Shimano will have retired HT2 & 3 😉

There may well be cheaper ways of saving weight though

This is a good point. The road bike thing is pretty new to me (but interesting) and I suspect the wheels I’ve got may well be better candidates for weight saving.

– You will need to get the BB shell “faced” to remove the paint – and allow the bearing cups to sit straight/flush

Worth looking at the whole picture – wheels may well be heavy but new ones may be £££, if transmission is worn then may justify new chainset.

TBH making a bike light by piecemeal replacement of parts is just about the most expnsive way of getting a light bike.

You will need to get the BB shell “faced” to remove the paint – and allow the bearing cups to sit straight/flush

If you like to do everything your supposed/told to do then you will. Otherwise dont bother.

Get some planet x model b wheels and some light tires, this would maybe be the best/cheapest way of saving weight

Get some planet x model b wheels

That’s much much more like it. I’d save 300g on the front wheel alone, so probably an overall saving of 6-700g on a pair of wheels 😯 ….. sold 🙂