Shimano Tiagra ST-4720 STI & BR-4770 flat mount calliper

Shimano's Tiagra Disc levers and callipers are what you should look for on your next commuter or winter bike. They have one less speed than 105 but apart from that you'd be hard pressed to tell the difference without a set of scales. The setup is reasonably easy, and they're light on maintenance and easy to bleed. If you really can't live without 11 speeds at the back they won't be for you, but given the quality of the shifting and the braking, they're a great choice. As an upgrade they're still expensive at full RRP, but you can find them a lot cheaper than that if you shop around.

• Pros: Great braking, accurate shifting
• Cons: Not 11-speed, not compatible with old 10-speed

Our review kit consisted of two ST-4720 levers and two BR-4770 flat mount callipers, for a 2x10 hydraulic disc setup. Setting the system up was simple enough. The hoses come filled with mineral oil and connected to the callipers, and there's an olive ready in the lever which is also full of oil. If you don't need to cut the hose then all you need to do is route the hose, poke a hole in the seal keeping the oil in the hose, and then tighten everything up.

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You will need to cut the hose, though, unless you're on a tall bike or something. That means you'll need to dig the insert out of the end of the cut bit, and stick it in the shortened hose. If you heat up the end of the hose with a hair dryer then you can press it in pretty easily.

Once you cut the hose you're in danger of losing some of the oil, but even with pretty extensive faffing with internal routing – which included sticking a bit of sharpened coathanger wire in the end of the hose to guide it through the frame – there was still no real need to bleed the brakes. The bite point was fine and both brakes were about the same. There's no free stroke adjustment on the ST-4720 lever, so you can't adjust the bite point once the system is sealed.

If you do need to bleed the brakes, it's pretty easy. There's an easily accessible cover on the top of the lever that gives you access to the reservoir. You screw an external reservoir into that, and pump mineral oil through the system from the calliper end until all the air is expunged. You need to be careful not to strip off the tiny 2mm hex key head on the reservoir cap, and it's best to remove your wheels to avoid getting oil on the rotors, but the process is straightforward enough.

If you're fitting this lever system as an aftermarket upgrade then the likelihood is that you'll be upgrading from a mechanical setup of some description. And the good news here is that whatever mechanical setup it is, these Tiagra hydraulics will be just miles better.

Shimano, SRAM and Campagnolo all have their champions when it comes to their disc brakes. Personally, I'm happiest with Shimano: they're easy to set up and bleed and they're powerful and reliable, with a host of aftermarket pads available to tune things to your liking. I don't know if we're still talking about whether you need disc brakes on your road bike, or whether you'll be fine with some nice dual pivot rim brakes, or some cantis, or some pressed steel single pivot brakes with cork pads, or rod brakes, or just using your feet on your velocipede. Things move on. Disc brakes are better.

> The stuff they never tell you about disc brakes

These specific disc brakes are very good indeed. There's plenty of power there and they're easy to modulate, and they're exceptional in the kind of filthy conditions that epitomise about half the year's riding round here.

The hood shape has been refined over the last few years and I find it pretty comfortable; there's a small lump where the hose exits the lever and if you hold the handlebar in a certain way that could be an issue, though it wasn't for me.

The levers are easy to use from the hoods and drops, assuming you have nice big hands: I can grab a handful happily enough but I wouldn't want the levers to be much farther from the bar, and I've got hands like shovels. You can adjust the reach inwards, but by doing so you reduce the active stroke of the lever, and because you can't change the bite point you might find yourself running out of room between the lever and the bar if your reach is especially short. For riders with smaller hands there are the ST-4725 levers – they're pretty much exactly the same, just with a smaller lever size and slightly adjusted ergonomics.

The K03S Resin pads on this test set are a bit smoother in feel but don't last as long as the K04S Metal pads, which aren't quite as nice to use in my experience but last a lot longer. Whether the brakes come with resin or metal pads is down to whichever your country's Shimano distributor chooses – in the UK it's resin. If you want metal you'll have to buy them separately. My pad of choice once it comes to renewal time is the SwissStop Disc 34 RS – it doesn't feature cooling fins but I've never really found them necessary for UK conditions.

The pads self-centre very efficiently, so there's no need to constantly fiddle with the setup, although the space between the pads and the rotor is pretty minimal and requires fairly accurate setup in the first instance. If your flat mount is a bit off – and many are – then you might find that they rub and some facing off is required, even if your mechanical discs (where the pads tend to sit further from the rotor) were fine.

Derailleur-wise, the Tiagra system is 10-speed at the back but Shimano, in its infinite and benevolent wisdom, has chosen to change the pull ratio so that the new 4700-series Tiagra isn't compatible with any other 10-speed Shimano road groupset. You can in theory use these levers with an 11-speed derailleur, though, as the pull ratios are the same or near as dammit. Shimano wouldn't recommend that, of course, as it likes you to have everything the same. Life's not always like that though.

I'd been running a Shimano 105 groupset on the bike before this (I'm gradually working my way down the range, it seems) and that was with an 11-34 11-speed cassette. So the Tiagra's 11-34 10-speed cassette offers exactly the same range, and for the first seven sprockets it's exactly the same in terms of sprocket size. After that it ramps up a bit more quickly. I wasn't convinced that I'd notice the difference, but actually I did, especially the jump from 26 to 30 teeth (15%) which feels like a bit of a big step down. It's not the biggest on the cassette – the jump from 11 to 13 teeth at the other end is 18% – but it is the most noticeable, as it always comes at a time when you're working pretty hard up a hill. I stopped noticing after about a month, and now I've adjusted my filter to the bigger jumps. It's really not an issue.

> Your complete guide to Shimano road bike groupsets

Everything else about the shifting is great. The shifts at both ends of the transmission are crisp and accurate, and the lever action is light but positive. It's not as slick as the top-end groupsets, but in terms of actual functionality it's really not far off, which is impressive from a fourth-tier groupset.

Overall, the Tiagra hydraulic disc setup is easy to get on with, and easy to recommend. If you're running a winter bike or an all-purpose machine then it's hard to see how you can do better than this really: you get the ergonomics and most of the performance of the higher-end groupsets in a good value package. You're missing a speed you probably won't notice, and it's heavier than the Gucci groupsets, but that's about it.

Verdict

Great performance for braking and shifting; perfect for your winter bike or commuter