Mrthfx

I have a Whyte Portabello hybrid, I wanted to swap to an adventure bike with drops. I thought as an alternative it might be easy to convert my existing bike instead, and save a bit of money.

It has hydraulic disk brakes but most brakes on drop bars seem to be cable operated?

The rear derailleur is a Shimano, so would I just have to get some Shimano road brake/ shifters and fit some cable operated calipers instead? Or is it a bit more complicated than that?

thanks

Simple advice: don't do it.

• You'll need to replace a lot of components because the derailleurs and brakes used on flat-bar bikes aren't compatible with the levers typically used on drop-bar bikes.




• You'd end up with a bike that doesn't handle very well because you're moving the handlebars to a completely different place and the rest of the bike geometry doesn't match that.

Sell the bike you have and buy the bike you actually want. If that doesn't fit in with your finances, a second-hand bike is almost certainly a better option than trying to convert your existing bike.

Assuming it also has Shimano brakes, probably it's enough to change the brakes and shifters. A short search would indicate this:
https://www.merlincycles.com/shimano-st-rs685-hydraulic-disc-brake-stis-br-rs785-disc-brakes-post-mount-75654.html

at a price of some 160 GB pounds so less than 200 eur for the brake/shift levers.

You would also need to mount them, connect the brake tubes (they are probably long enough), bleed the brakes, find the brifters (STI) with the correct number of speeds.

Also, the pull ratio (how much the gear cable must shorten for a gear change) might differ from MTB to road gear shifters, in which case you probably need new derailleurs (road).

I've checked and the 2018 version has Shimano Sora (road) groupset, so you could either go with combined hydraulic brake/shift levers for Shimano road 9 speed, or change the brakes to a cable/hydraulic or full cable combo (if available).

EDIT: the 2019 version seems to have Shimano Deore rear derailleur, so MTB not road. Not sure of your exact year/version and derailleur.

Hydraulic road brakes are available on 105 and up. I think road and MTB levers and calipers are compatible.

Your 10 speed Deore derailleur will not be compatible with 10 speed road shifters. Shimano derailleur pull ratios diverged when MTB drivetrains reached 10 speeds.

As David said, the main problem is hybrid bikes have different frame geometry than drop-bar bikes. They are longer (greater reach) because flat bars do not extend so far forward as drop bars. The Portobello also seems to have a large stack (height of the top of the steerer tube above the BB). You'd have to use a very short stem to get a usable hand position, which will negatively affect the steering.

A set of hydro road shifters is not cheap, you'll either have to learn how to bleed hydro brakes (and buy a bleed kit) or have a LBS do it for you; and you are taking a risk that you'll end up with something unridable, or at least very compromised. Selling the bike and getting a new one is a better option.