Suffering on the hills? Find out how to get lower gears to make climbing easier

For this article, we’re assuming that you have a bike with derailleur gears rather than hub gears.

Bike gear basics

If you have a typical derailleur setup on a modern bike designed for the road, the chances are that you have one or two chainrings on the chainset (at the front) and up to 13 sprockets on the rear wheel in what's usually called a cassette or cluster (the exact number will depend on the groupset you use).

Shimano Dura-Ace R9200 - Pinarello Dogma F - Detail (CREDIT Irmo Keizer_Andreas Dobslaf)-13 (credit: road.cc)

The size of the gear is determined by the chainring and sprocket combination that you use. Running the chain on a larger chainring gives you a larger (harder) gear that moves you further forward with every pedal revolution, as does running the chain on a smaller sprocket.

That’s simple, right?

But what if you’re running the chain on the smaller chainring and the largest sprocket and the gear is still too hard? You can work on your fitness, naturally, but you can also make changes to your equipment.

Changing your cassette

Cassettes come with various combinations of sprockets.

We’ll take Shimano’s fourth-tier Tiagra groupset as an example (the Shimano Cues groupset will replace the Tiagra, Sora, and Claris groupsets on road bikes). Shimano offers its 10-speed HG cassette in several different configurations, including with an 11-tooth sprocket up to a 32-tooth sprocket – often written as 11-32T. It also offers an 11-34T cassette.

Shimano CS HG500 cassette (credit: Shimano)

All other things being equal, the 34T sprocket on the 11-34T cassette is going to give you an easier gear. If your bike is currently fitted with an 11-32T cassette, switching to an 11-34T cassette will make steep climbs slightly less of a struggle, although you'll go a shorter distance for each pedal revolution.

Swapping one cassette for another is a straightforward job, but only if you have the right tools, including a cassette tool and a chain whip. If you don’t have these, you can ask a bike shop to do the job for you.

If you're currently using a 10-speed system, make sure your new cassette is 10-speed too, and ensure it's compatible with the rest of your components. The freehub on your rear wheel will be splined, so it'll only accept certain cassettes. The various systems out there aren't all interchangeable.

> Learn how to fit & remove sprockets in 12 steps 

A Shimano Tiagra CS-HG500 10-speed cassette currently costs £34.99 at full RRP.

SRAM kicked off the use of double chainsets and wide-range cassettes a few years ago with its WiFLi designs, which were the first systems to combine a 50/34T chainset with an 11-32T cassette. That seems conservative by today’s standards.

2024 midrange bike vs superbike canyon ultimate cfr climbing 2 road.cc kit (credit: road.cc)

The latest version of Shimano’s 105 rear derailleur will handle an 11-36T cassette, which opens up a range of possibilities.

Shimano offers 11-34 cassettes at Dura-Ace, Ultegra, 105, and Tiagra levels, and much wider options with Cues. You can get an 11-50T 11-speed Linkglide cassette, for example, which will work with a Cues 10/11-speed rear derailleur.

The SRAM alternative

These days, SRAM does things differently, offering smaller chainring combos and wide-range cassettes across the board. SRAM’s top-level Red AXS groupset comes with cassettes from 10-28T right up to 10-36T, for example. The smallest Red AXS double chainset is 46/33T.

2024 sram red xplr news hero (credit: road.cc)

SRAM Red AXS XPLR, designed for gravel, comes with a 10-46T cassette, although you’ll need a Red AXS XPLR rear derailleur to go with it because the standard Red AXS option can’t handle a sprocket larger than 36T.

Bear in mind, though, that the upgrade path could be painful as you’ll need a new transmission and wheels with SRAM's XDR driver, but if you want high-tech shifting and low ratios, it might well be worth it. 

Campagnolo Chorus 12 speed cassette (credit: Campagnolo)

Campagnolo

If you have a Campagnolo system, then up until a few years ago, most groupsets were limited to a 29-tooth sprocket. However, things have changed over in Italy too, Centaur offering 11-32T and 12-32T cassettes, and Chorus going further with an 11-34T option.

2024 Campagnolo Super Record S Wireless front and rear mech (credit: road.cc)

Second-tier Super Record S Wireless and top-level Super Record Wireless come with an 11-32T cassette option that can be matched with chainset combos as small as 45/29T.

> Campagnolo launches new second-tier Super Record S electronic groupset offering “greater affordability”... and it'll still cost you over £3,000

We're going to focus on Shimano systems in this article, as that covers the majority of bikes out there.

Rear derailleur capabilities

If you change your cassette, you need to bear in mind the maximum sprocket your rear derailleur will handle, and its capacity. The capacity is the total difference in chainring and sprocket sizes that it can take. You can look these figures up on the relevant brand's website. You can choose a new cassette with a wider range than your current one, but only if your rear derailleur can handle it. 

Say you have 50-tooth and 34-tooth chainrings: the difference between the large one and the small one (50 minus 34) is 16 teeth.

And say your bike is fitted with an 11-34T cassette: the difference between the large one and the small one (34 minus 11) is 23 teeth.

Add them together and you get a total difference (16 plus 23) of 39 teeth.

2024 Look 785 Huez 105 Di2 - rear mech.jpg (credit: road.cc)

Shimano’s 105 Di2 rear derailleur takes a maximum sprocket size of 36T and has a total capacity of 41 teeth. That means you can use it with the setup described above.

Shimano’s Dura-Ace rear derailleur takes a maximum sprocket size of 34T – which would be fine – but it has a total capacity of 37 teeth, which is less than you need for the combo outlined above. To deal with that, the Dura-Ace Di2 rear derailleur has Shimano’s Gear Position Control (GPC) enabled, blocking the smallest two sprockets of the cassette when the chain is in the smaller chainring.

You might find that in some cases, components work fine outside of the limits stated by the manufacturer, but don’t tell anyone we said that. If we were swapping our cassette for a larger one, we’d certainly try it with our existing rear derailleur before shelling out any money on a new one, even if that wasn’t strictly within the manufacturer’s recommendations – but that's your call, of course.

Swapping your chainset

If you’re on a road bike, you’ll probably have a double chainset – with two chainrings – although 1x single chainring setups have become more popular over recent years. There are various common double chainring combinations.

If you have a 52/36T (semi-compact) setup, for example, and you find the gearing too hard, you can buy a 50/34T (compact) chainset or fit smaller chainrings to your existing cranks (check that the new chainrings are compatible with your chainset before buying).

You’ll also need to alter the position of your front mech and get yourself a new chain (or shorten your existing chain).

Like rear derailleurs, front derailleurs have a maximum capacity. Here, it relates to the difference in size between the large chainring and the small chainring. So, say you’re using 50/34T chainrings: the difference is 16 teeth.

The capacity of a Shimano 105 front derailleur, for example, is 16T so it’ll cover all of the common double chainset combinations.

If a compact chainset isn’t small enough, you can go lower still with a sub-compact option. The gravel/adventure bike movement has been the main driver of sub-compact chainsets. Shimano offers its GRX RX820 gravel chainset with 48/31T chainrings, for instance, while its RX600 chainset comes with 46/30-tooth chainrings.

Going for a triple chainset

One final option for changing your gearing is to swap from a double chainset to a triple chainset, although there aren’t many out there anymore. A typical triple setup for the road has a 30T inner chainring compared with the 34T inner chainring of a compact setup.

Over the past few years, the introduction of cassettes and rear derailleurs that provide a super-wide range of gears has meant that triple chainsets have fallen out of favour. As far back as 2017, we were asking whether we were seeing the death of the triple chainset, and things have only declined for the triple since then. That said, some people get on well with triples, especially for touring; it comes down to personal taste.

Swapping from a double setup to a triple is pretty complicated. You’d need to change your shifters, your chainset and probably your derailleurs too.

You can still find Shimano’s Tiagra 3x10-speed, Sora 3x9-speed, and Claris 3x8-speed components with retailers, although these groupsets are being phased out in favour of Cues (below), which offers only single and double chainsets.

2025 Shimano CUES drop-bar crankset (credit: road.cc)

> Shimano officially launches entry-level Cues groupsets for drop bar road and gravel bikes, including 9, 10 and 11-speed options “at a reasonable price point” 

Good luck out there on the climbs.