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I have a last generation 105 5800 groupset currently set up with mechanical disc brakes. I'm thinking about upgrading to hydraulic brakes. Do I need to change my shifters in order to do this?

3 Answers 3

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You need to change your shifters. Brake levers designed to pull wires cannot be modified to push fluid.

You might choose to install hydraulic brake calipers that are cable-operated but that's just an extra step in the brakes.

You need compatible shifter levers.

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    Might be worth clarifying that the "yes" is to the question in the body of the post, not the one in the title! (I was confused for a moment when I started reading the answer...)
    – psmears
    Commented Aug 15, 2023 at 10:36
  • @psmears good spotting, thank you. I have no idea how I flipped it like that, but you're correct.
    – Criggie
    Commented Aug 15, 2023 at 19:30
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    The original post asks two questions, one in the title and one in the last sentence - they're basically the same but with the sense flipped. Your "yes" did make perfect sense following on from the end of the question; now it makes sense both ways :)
    – psmears
    Commented Aug 15, 2023 at 21:27
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As an alternative to the expense of upgrading to hydraulic STIs, there are cable-to-hydraulic adapters available. I recall seeing some Genesis road bikes equipped with them in a local bike shop.

We don't do product recommendations on Stack Exchange, but here's some examples of what I'm talking about.

https://www.liv-cycling.com/gb/conduct-hydraulic-disc-brake-upgrade-kit

https://www.bikeradar.com/reviews/components/brakes/disc-brake-systems/video-trp-parabox-disc-brake-system-review/

I have no personal experience of such adapters, though, so you'd need to do your own research!

From linked website, to avoid link-rot

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    Nice find! I think your link was just to a hose kit at 20 UKP, so I've swapped it for one to the full kit.
    – Criggie
    Commented Aug 15, 2023 at 9:27
  • Thanks, @Criggie! Commented Aug 15, 2023 at 10:34
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STIs include the internals actuating the brakes, i.e. the mechanism pulling the cable or the reservoir including the brake fluid etc. For this reason, they are not interchangable, even within the same generation of a groupset (if both mechanical and hydraulic options exist, for example Ultegra R8000).

You need ST-R7020 levers including matching BR-R7070 calipers, the rest of your groupset (R5800 front and rear 11-speed derailleurs) should still be compatible.

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