I’ve got 105-5600 10-speed STis on my roadbike. On the whole, they’re flawless.
Due to my delicate hands, I fitted the Specialized wedges that reduce the reach by stopping the lever retracting all the way, which works great in that respect.
BUT: I’ve got Shimano mechanical discs – originally R505s, now R517s. They’re fine, but not great. No matter how I adjust the pads, the lever ends up hitting the bars before I lock up. I’ve just realised its due to the reduced throw of the lever.

Are there STis with adjustable reach which doesn’t affect the effective cable pull? Do the newer hydraulic brakes get around this problem? Anyway I can increase the cable pull for the reduced lever throw, by somehow increasing the size of the cam?

some of those converters for running v brakes with an old canti-compatible lever?

bit ugly, though

Not used Shimano cable callipers but I have some Shimano STI levers mated to BB7’s with a reach adjuster wedge fitted and no issues with getting them to bite early, but still have rotor clearance, and they will lock well before bottoming out.

Do the Shimano callipers not have enough adjustment to get the pads close enough or is the issue that if you do they rub?

RE: leverage/cable pull. I know the pull ratio changed with the 5700/6700 series STIs, but 5600 should be the old ‘standard’ road pull, could the new R517 callipers be expecting the newer pull ratio?

eurgh, ugly, but it would work…

Need to find somewhere to install it out of sight…

RE: leverage/cable pull. I know the pull ratio changed with the 5700/6700 series STIs, but 5600 should be the old ‘standard’ road pull, could the new R517 callipers be expecting the newer pull ratio?

Highly possible. Damn. Cable pull ratios are different for the mechs too I believe.
New groupset time…

Using a Tiagra lever with a reducing wedge and BB5, the key I found was setting the pad clearance and setting the actuating arm so that it’s taking up any cable slack…

Handy guide the method must be applicable to other mechanical discs I’m sure…

Other things to consider; are the cable outers “Compressionless”? are the ends cut perpendicular and fully pressed home in the ferrules? basically are there any places where a bit of “squish” might come from the cabling, wasting your input rather than transferring it all to the calliper?

Can’t help thinking that using a travel agent would make the brakes a bit digital perhaps…