Converting Shimano road bike with STi hydraulic brake levers to flat bar levers?

[slope]

Is this possible? Unable to find any conclusive evidence elsewhere - which could just be my poor search skills🙄

Specifically, on a new unused bike, swapping out a pair of new Tiagra ST-4720 levers, replacing drop bars with new flat bars and either Shimano BL-MT401 or BL-MT501 hydraulic brake levers? Whilst retaining the flat mount Tiagra BR-4770 calipers?

[rafletcher]

Don’t see why not, hydraulic brakes started on mountain bikes after all, and hydraulics aren’t fussy about “pull” length as the pad movement is small and the fluid incompressible. I’d be more worried about the geometry, as that of flat barred bikes and those with drops differs considerably IIRC. And what about the gear shifting? I don’t know if shift ratios are the same betwixt drop bar levers and flat bar levers - but I’d hazard not, this being Shimano.

[grams]

All Shimano hydraulic brakes are interchangeable AFAIK.

There are 4700 series flat bar shifters but they are strangely pricey.

You could also fit much cheaper MTB 2x10 shifters or Tiagra 4600 but you’d have to change the rear mech. Not sure about the front one.

[slope]

Perhaps it would help to add some context to my enquiry. The bike in question is a Vitus E-Substance. Strangely, it appears to have a more suitable front end geometry than the flat bar specific Boardman HYB 8.9E I recently acquired. The top tube length is good compared to my other older bikes. It also has longer chainstays meaning there's more room to fit 35mm+ tyres and mudguards - the Boardman is very tight behind the seat tube as can be seen in the pic below. The colour is nicer too

Getting the gears I want will not be a problem. I have all the necessary components for that,

I do like the Fazua system thus far - and the price of this particular Vitus, compared to similar specced bikes. But I know I most definitely do not want drop bars or their STi type levers. Here's a poor pic of the modified Fazua Boardman to get an idea of what I'm intending.