Shimano 105 (RS505) Hydraulic STI Road Disc Brake Set

With its RS505 Hydraulic STI Road Disc Brake Set, Shimano has brought hydraulic braking down to 105 level, making it accessible to people buying sub-£1000 bikes like the excellent Pinnacle Dolomite 5. And generally it gives a good performance. The highlight is the braking, with the shifting – and the ergonomics – lagging behind a bit. But it's still a solid performer and good value to boot.

Shimano is moving over wholesale to flat mount disc brakes, from the mountain bike standard of post mount. It means smaller, less obtrusive callipers and neater lines on your road bike. The 105-level callipers are the first to be generally available, and I've now used them on three bikes: the Pinnacle mentioned above, a Kinesis 4S Disc and a Boardman Road Pro Disc (review to come on road.cc soon). On two of those bikes the callipers were paired with Shimano's own rotors, and on the Kinesis I used TRP centrelock rotors. And in all cases, the braking was easy to modulate and predictable.

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The disc brake debate will continue, but for me they're better brakes. They have their downsides: they're more fiddly to set up for a start, and the tolerances on the mount are tighter. Many bikes, especially cheaper models, benefit from a visit from the Park DT5.2 facing tool to make sure the mount is perfectly aligned. The gap between the pads and the rotor is small, so dirt ingress can make them noisy on muddy rides through the lanes, and rotors need to be very true so they don't rub.

Once they're set up, though, the positives far outweigh the negatives. They give stronger braking for a given lever force, so your hands don't have to work as hard. They're far more predictable when the weather's foul. The pads on a hydraulic system self-centre, so you don't need to adjust them as they wear. And, of course, you're not wearing through your rims. Overall, for most types of riding, they're better. I guess at some point a pro rider could lose the top of their finger in a pile-up or something, but that's a fairly long way down the list of my braking concerns.

These 105 flat-mount callipers are great. Paired with the levers they offer really good, predictable braking in all conditions. Shimano had some issues with the first generation of hydraulic levers where the bite point was too far into the lever stroke, but that's not the case any more: once they're well bled they bite quickly and the braking force is easy to control.

The whole I-can-lock-up-my-wheels-with-rim-brakes-so-why-would-I-need-discs argument is a big red herring, really; what you get here is better, more controllable braking for a given effort at the lever, most notably when it's tipping down and your rims are soaked. It's just easier to brake, and that means you're more likely to do it well when you're tired at the end of a ride, or it's freezing out and you can't feel your fingers.

I've tried to cook the brakes on all the various road-disc systems I've tried, and with very little success. The most you can manage is a bit of brake fade when you deliberately drag a brake down a long descent. There's no situation where I'd worry about being able to stop on these, and I'm a big lad who likes to go fast down hills.

Bleeding the 105 brakes is easy enough. The internals have been shoved around in this lever; in the Ultegra and Di2 levers the bleed port is under the top cap of the lever, whereas here it's under the rubber hood cover at the bottom, so you can just flip up the rubber to expose it. You'll need a Shimano bleed kit, but if you have one it's a five-minute job: undo the cap on the lever, fit a funnel, stick a syringe full of mineral oil on the bleed port on the calliper, loosen that, push the oil up through the system to flush out any air and tighten everything back up again. It's something you'll have to learn to do if you're new to disc brakes, but it's not exactly hard.

The new layout of the levers has some repercussions with the shape of the hood, which has quite a prominent bulge on the inside bottom surface where the hydraulic hose exits. I'm tall with a long reach, and I tend to put my hands high on the hoods, so it wasn't an issue for me. But if you like to hold the shoulder of the bar, that's where your thumb is, and other people have mentioned to me that it's not as comfortable as other Shimano levers. I found the top section of the hood pretty comfy, and the bulbous top section is easy to grab for a semi-aero position. Let's be honest though, they're not going to win any lever beauty contests, these.

If braking is more or less faultless, shifting is more of a mixed bag. All levers benefit from a careful setup to achieve really good shifting, but you do seem to have to be extra careful with these 105 units. Of the three bikes I've tried them on, two have had issues with the shifts being a bit sticky – not to the point where it's a big issue, but just enough to introduce a bit of doubt as to whether you've shifted or not.

This isn't helped by the lever: Shimano uses its vivid indexing on these 105 levers, which gives a nice light action, but on other STI levers the shift feedback is more obvious. Here it's a little vague; the click is there if you're watching out for it, but it's easier to miss if you're not concentrating. There's the perennial problem of all Shimano STI levers too: if you catch the brake lever when you're shifting to a smaller sprocket, the mechanism doesn't engage and the lever just swings. I wish they'd sort that out.

The bottom line here is that shifting performance is fine, but I wouldn't say it was 105 level, certainly not when compared with the rim-brake lever. It's not as good as that. I'd say it's more like Sora, but now that Sora's been given the treatment, maybe even that's not fair.

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It doesn't mean the 105 hydraulic levers should be discounted, far from it. The performance is good, with the braking the highlight. These levers bring hydraulic braking down another notch in price, meaning you can have the benefits of hydraulic disc braking on bikes for cycle-to-work money, and that's great. The shifting is good but it's not the highlight.

It'll be interesting to see how SRAM's new Apex hydraulic groupset compares when it lands; that's only available as a 1x system so it won't suit everyone, but it looks like it'll be a great value option.

The RRP for these levers and callipers is £399.99, but as always you can get Shimano stuff much cheaper out in the real world, with a full 105 hydraulic groupset changing hands for only about £50 more than the RRP of the levers.

Verdict

Good hydraulic braking performance now available at a lower price