Gravel bike gearing: Everything you need to know

The best gearing for your gravel bike, how to get lower gears and 1× vs. 2×

shimano-grx-limited-3

paul-norman-cyclist-1byPaul Norman

JULY 19, 2023

The best gearing for your gravel bike gives you low enough ratios to climb seriously steep off-road terrain, enough gears that you don’t have huge jumps in the effort required, and enough top-end that you don’t feel constantly spun out on the road.

All the major groupset brands now make dedicated gravel drivetrains to meet these needs, whether you’re doing general gravel riding, mixing up gravel and road, or going bikepacking.

We’ll look at the best gearing options for gravel bikes, how to compare gearing, and the pros and cons of single (1×) and double chainring (2×) groupsets.

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Finally, we’ll run through what’s available from Shimano, SRAM and Campagnolo, as well as some options to increase your range of gears.

Do I need gravel-specific gearing?

SRAM crank and FD on road bike
Matthew Loveridge / Cyclist

When gravel bikes first became a thing, there weren’t a lot of gearing options tailored for gravel, so the first generation of gravel bikes usually had a compact road crankset (50/34 was most common) paired with a wide-ish range cassette that usually maxed out at 30 or 32 teeth.

This gave adequate gear range for most unloaded gravel adventures, but wasn’t optimal for riding on difficult terrain and loose or muddy surfaces.

Bikepacker in bivvy bag next to bike and lake
Canyon

The growth of bikepacking, which adds extra weight to your gravel bike, also called for a lower gear range.

Gravel’s rising popularity meant that groupset makers saw the potential to produce gravel-specific groupsets that offered lower gear ratios for better off-road capability.

These included clutched rear derailleurs to ensure better chain retention, smaller chainrings and often wider range cassettes.

The best gravel bikes now offer wide gear range with the low gears you need to tackle the steepest off-road terrain, and enough high ratios to ride at speed on easier surfaces.

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What’s the best gearing for gravel?

SRAM drivetrain on gravel bike
Matthew Loveridge / Cyclist

Gravel riding calls for lower gearing than needed for a road bike, to handle tricky terrain and loose surfaces with an even cadence and to avoid having to jump off the bike and push.

That either means wider range or sacrificing high ratios in favour of more low-speed grunt. Both are options, depending on the groupset and configuration you choose.

Unless you mix a significant amount of tarmac into your gravel rides, you’re not likely to be using the higher gear ratios that a road bike groupset provides, so there’s an advantage in lower gearing overall to provide smaller jumps between gears at the lower speeds most gravel riding entails.

Gravel bike groupsets typically cut out these higher ratios in order to provide a good spread of lower gears.

Gravel tyre
Joseph Branston / Cyclist

It’s also worth bearing in mind that the wider tyres fitted to gravel bikes will travel further per turn than a narrower tyre, as explained below. This means that the effective gearing is slightly higher for a gravel bike than for a road bike with the same groupset ratios.

In general, road bike gear ratios don’t go much below 1:1 (e.g. a 34-tooth chainring with a 34-tooth large sprocket on the cassette), although SRAM’s X-Range 12-speed gearing provides a 10-36 cassette option and 12-speed Shimano 105 Di2 has an 11-36 cassette, both of which provide sub-1:1 lowest gear ratios. Both also offer you a reasonably high top gear for fast road riding.

Sub-compact cranksets – i.e. those with smaller chainrings than the conventional 50/34 compact – were first offered by brands including FSA and Praxis Works and typically have chainring sizes of 48/32 or 46/30.

Shimano launched its GRX gravel groupsets in 2019 that followed this trend, while SRAM has smaller chainring options as part of its 12-speed eTap AXS groupsets.

The smaller chainrings mean that there’s not as much top end gearing when you hit a fast tarmac section or a downhill gravel stretch, but gravel riders are in general prepared to accept this in exchange for more low range.

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How do I compare gearing?

Cassette on gravel bike
Matthew Loveridge / Cyclist

It’s useful to be able to compare across groupsets to see how much range a gravel groupset gives compared to a road bike groupset, how many lower ratios you’re getting and how much high gear range you’re giving up in exchange. But it’s not obvious how, for example, a 50:28 gear ratio compares with a 46:24.

There’s a standard way to compare gear ratios though, by expressing them in gear-inches. For any given combination of chainwheel and cassette sprocket, this is the number of teeth in the chainring divided by the number of teeth in the sprocket and multiplied by the wheel size in inches.

This doesn’t tell you how far the bike will actually move per turn of the pedals, but does allow a comparison between gear ratios. The equivalent metric measurement is metres of development, which uses the wheel circumference rather than its diameter and so does give you a figure for distance travelled by the bike per turn of the pedals.

Even this is approximate though, as the actual distance travelled will be dependent on the tyre’s height above the rim, which will be greater for a wider gravel bike tyre than for a narrower road tyre.

Gear-inches are sometimes compared for a nominally 27 inch tyre diameter without taking account of the difference in tyre size. You can work out the gear-inches for your system yourself, but there are also gear-inch tables available online.

Bikecalc.com has a gear-inch table that takes account of tyre size, although you’re going to have to work out which numbers apply to the sprockets on your bike. Sheldon Brown has a calculator that lets you select from many, but not all, of the common cassette options and tyre sizes.

The other useful option for comparing gearing is to use the spread in its range from the highest to the lowest ratios.

Gravel bikes typically offer much wider gear ranges than road bikes. Gear range is usually expressed as a percentage difference between the smallest and largest ratios available, so for example a 10-42 cassette with one chainring would give you a 420 percent range ie (42/10)*100.

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1× vs. 2× for gravel

1× crank on gravel bike
Shimano

One of the big differences between road bikes and gravel bikes is that the latter are often equipped with single ring groupsets, whereas they’ve not really taken off for road bikes, the vast majority of which still use a two chainring crankset.

A single chainring has advantages when riding off-road. It means that you can dispense with the front derailleur, making for a simpler set-up with less to go wrong.

Front derailleurs are also prone to collect mud or vegetation that will impair shift quality, and having one may encourage debris to collect behind the bottom bracket too. It can also make it more difficult for a bike designer to add the maximum frame clearance for wide tyres.

Because the chain doesn’t need to move off the chainring and you don’t want it to either, to avoid a dropped chain the teeth on single chainrings can be made deeper to encourage chain retention.

Narrow-wide chainring teeth
Wolf Tooth

They’re also often shaped so that alternate teeth are wider and narrower, meaning they mesh more precisely with the wide and narrow links of the chain, again improving chain retention and promoting the removal of debris from between the links.

You can fit a chain retention device to make even more sure that you don’t lose a chain, although the combination of a good 1×-specific chainring and a clutched derailleur make this a lot less likely than on a double chainring set-up.

The big advantage of a double chainring set-up is that it offers smaller jumps between ratios, while still offering a similar overall gear range.

You’d expect a bike with a double crankset and 24 speeds (i.e. 2×12) to have twice as many gear ratios available as a single ring 12-speed set-up but in practice there are ratios on the large ring that are close to those offered by the small ring, so the actual number of discrete gear ratios is often considerably fewer than 24.

Nevertheless, most two ring configurations will provide more overall range than a single chainring, although that’s not always the case, as we’ll explain below.

A front derailleur makes reseating your chain a possibility if it drops off your chainrings, whereas you’ll need to get your hands dirty to reseat a dropped chain on a single chainring.

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Shimano vs. SRAM vs. Campagnolo: Which is best for gravel?

All the major groupset manufacturers have gravel groupset options in their portfolios, which we’ll run through.

We’ll also recommend a set-up for all-round gravel riding that will give you plenty of lower gearing and, in most cases, a high gear that’s the match for a road bike groupset if you expect to mix tarmac with off-road and want to avoid spinning out.

Shimano GRX gravel groupsets

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Shimano GRX is currently available in 11-speed and 10-speed options and the 11-speed groupsets are available either with either Di2 electronic or mechanical shifting.

Mechanical 11-speed GRX comes in two spec levels, RX800 (Ultegra equivalent) and RX600 (105 equivalent). 10-speed GRX groupsets are denoted RX400 (Tiagra equivalent).

It gets even more diverse as you can select between 1× and 2× groupsets and below that there are multiple chainring sizes, with RX800 offering 48/31 and RX600 having 46/30 chainrings, while 10-speed RX400 also comes with a 46/30 double chainset.

Go single ring and RX800 offers 40t or 42t chainrings, while RX600 is 40t only and RX400 does not offer a single chainring option.

11-speed GRX works with a range of different Shimano cassettes up to 11-34 for two chainring groupsets and 11-42 for single ring, although these are not designated GRX but come from Shimano’s road and mountain bike ranges respectively. 10-speed GRX400 can handle an 11-36 cassette.

Shimano 1×11 speed GRX groupsets give you a maximum range of 418 percent, while 2×11-speed gives 474 percent range. 10-speed GRX has a potential 502 percent range.

For all-round gravel riding, we’d suggest an 11-speed two chainring set-up with a 48/31 crankset and an 11-34 cassette, while a single ring 40t chainset with an 11-42 cassette gives a low ratio below 1:1, but doesn’t give you the same top end gearing.

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SRAM gravel groupsets

Sram Apex AXS groupset
Matt Buckley

Rather than a separate gravel groupset range, SRAM offers gravel configurations for its AXS road bike electronic groupsets. It sub-brands its gravel groupsets as XPLR and offers a range of crankset and cassette options for gravel riders in its RedForce and Rival and Apex AXS 12-speed ranges. They can be either single chainring or double chainring, with a range of chainring sizes for both.

SRAM offers a Wide double chainring option with smaller 43/30 chainrings for gravel. The chainrings are positioned 2.5mm further from the bottom bracket centre, which adds clearance around the more widely spaced chainstays found on many gravel bikes. Maximum range for Wide groupsets is 516 percent.

A more recent addition to its range, the SRAM Apex AXS 12-speed groupset is a single chainring only electronic groupset aimed particularly at gravel riders. The SRAM Apex XPLR AXS groupset has a range of chainring size options, with Wide spacing, from 38t to 46t, paired with 10-36, 10-44 and 11-44 cassettes.

Alongside Apex XPLR AXS, SRAM has the Apex Eagle AXS 12-speed electronic groupset. This uses a 10-50, 11-50 or 10-52 cassette, giving very low gearing options with wide range, although the components including the chain are not cross-compatible with Apex XPLR AXS.

There are also 12-speed mechanical shifting equivalents of both the Apex XPLR and Apex Eagle groupsets.

You can also buy SRAM 11-speed single ring groupsets configured for gravel riding at Force, Rival and Apex levels, which can accept a 10-42 or 11-42 cassette.

Our recommended configuration for the all-round gravel rider would be a 46/33 crankset with a 10-36 cassette if going for a two chainring configuration, which gives a top gear that’s as fast as a road-going bike but plenty of low gearing. If you want a single chainring, 40t with a 10-44 sacrifices a little top end speed but still goes as low.

Campagnolo Ekar gravel groupset

campagnolo_ekar_sideon

Campagnolo Ekar is a 13-speed single chainring mechanical groupset. It offers three cassette options, including two that start with a 9-tooth sprocket: 9-36 and 9-42, as well as a 10-44. It pairs that with 38, 40, 42 or 44-tooth chainrings for a wide 467 percent maximum gear range with relatively small jumps between ratios.

Ekar is lighter than both Shimano GRX and SRAM eTap AXS 1× options.

For all-round gravel riding, we’d recommend a 40-tooth chainring, paired with the 9-42 cassette for a range that goes down below 1:1 and a top ratio that’s almost as high as the 50/11 of a compact road groupset.

I need lower gears for gravel – what are my options?

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If you want to preserve your high gear ratios, you’ll need a wider range cassette to add lower range, which means a larger spread of gears and larger jumps between gear ratios as you move across the cassette.

The easiest ready-made option for extra-low gravel gearing is provided by SRAM 12-speed electronic shifting.

SRAM’s road groupsets use the same wireless protocol as its mountain bike groupsets to communicate between the shifter and the derailleur. This opens up the option to mix drop bar controls with an MTB rear derailleur in a so-called mullet build.

The SRAM Eagle eTap AXS rear derailleur is designed to work with an MTB cassette with up to a 10-52 range, giving you a very wide gear spread of 520 percent and ratios well below 1:1.

You can perform a similar trick with 11-speed Shimano Di2 MTB derailleurs, pairing them with gravel Di2 shifters to give you single chainring options up to 11-46 or double chainring cassette options up to 11-42.

Shimano doesn’t exactly encourage mixing MTB components with gravel and road kit however, so there are plenty of compatibility pitfalls. For example, you can’t mix GRX and MTB derailleurs in a Di2 drivetrain – it has to be one or the other. If you want to get into the details, we’d recommend a very close reading of the brand’s compatibility charts.

RD cable converter pulley
Wolf Tooth

If you’ve got a mechanical Shimano set-up, you can buy a cable pull converter such as the Wolf Tooth Tanpan that let you use road shifters to operate a mechanical mountain bike rear derailleur, which would normally be incompatible, opening up mechanical mullet build options.

The alternative to a wider spread is to lower your gear ratios overall by fitting smaller chainrings. SRAM 12-speed single rings go down to 36 teeth and Campagnolo Ekar down to 38 teeth.

Aftermarket RD cage
Garbaruk

Move away from the big three groupset brands and you have other options. Garbaruk, for example, sells derailleur cages to fit Shimano and SRAM that permit the use of larger cassettes (e.g. 11-50t) while the Wolf Tooth Road Link hanger simply moves your rear derailleur further away from the hub to create extra clearance for mountain bike sprockets.

Both brands sell a range of chainring sizes compatible with Shimano GRX and SRAM eTap AXS cranks too. Meanwhile e*thirteen has options to increase gear range including a premium lightweight 9-45 12-speed cassette.

Make sure you do your homework if you’re exploring the aftermarket as compatibility isn’t always straightforward. There’s a wealth of content on YouTube and bike forums exploring all manner of weird and wonderful combinations.

If you want a wide ratio option from a major brand, we’d recommend the Apex Eagle AXS groupset (or the mechanical shifting Apex Eagle equivalent) with an 11-52 cassette and a 42t chainring. This would give a wide range configuration for bikepacking or steep off-road riding, plus the cassette has the benefit of fitting on a standard Shimano 11-speed freehub (with a 1.85mm spacer) rather than needing a SRAM XDR freehub.