Can I swap front & back brake levers on Shimano ST-RS685? (hydraulic road disk brakes)

Question

I have Shimano ST-RS685 hydraulic disk brake set.

I'm used to having front brake lever on the right and rear on the left. (UK). But this bike has front on the left and rear on the right.

Is it possible to swap them over?

I understand GCN made a video on this:

But in this video the cables have the junctions that you can unscrew and exchange cables quickly. Mine doesn't have this junctions. Is it still possible?

The video mentions "lengthier", does that mean it can be done but the bar-tape has to be removed etc?

Answer 1

Yes, it is possible.

You have to undo the bar tape, and remove the hoses from your brake levers by unscrewing the compression nuts. Before you unscrew them, remember how many threads are still visible, so you know how hard to screw them back in later.

To connect the hoses back to the levers you can follow the Shimano dealers manual for your brake levers, which you can find on the Shimano website.

When you reconnect the hoses, you have to use new insert pins and olives for your brake hose, because reusing the old ones will not seal the connection correctly. You can find them by searching for "SM-BH59-JK-SS olive" and cost around 1€.

While your brake hoses are disconnected some braking fluid might get lost and air can get trapped. In that case you have to bleed your brakes after the installation.

Answer 2

Yes, you absolutely can swap the lines between front/rear, that holds true for all road hydro groups. Out of the box ST-RS685 used to come without quick release connectors, so you'll have to do something along these steps:

1. Undo bar tape wrap from stem to levers.
2. Unscrew hose furniture from levers.
3. Screw hose furniture into the opposite levers.
4. Wrap the tape back, check the brakes.

That said, step #3 might go wrong in many ways. It's usually not recommended to reuse hose furniture, especially between different levers because connection might leak, in which case you'd have to cut hoses, install new furniture and assemble everything again.

If some oil leaks, you'd have to bleed the brakes.

The hose length might also be insufficient, in which case you'll have to install new hoses (both BH-59 and BH-90 work with ST-RS685) and furniture (brake olive kit) and do a complete bleed.

With mineral oil, things might get very messy, so I suggest to at least remove brake pads and wheels in order to prevent contamination. Try no to work brake levers without pads/disc.

If you feel uncomfortable doing maintenance on hydraulic brakes, I suggest to ask a local bike shop for help. Even after numerous brake services, I still dread anything that has to do with brake fluid.