Every bike brand worth its salt has a gravel bike in its range but there’s a vast array of different spec choices and setup options out there, from gearing and wheel sizes, to tyre width and accessories.
Some bikes are geared towards fast rides on and off-road, while others are set up to carry luggage on long-haul adventures, well off the beaten track. Which is right for you? What are the spec options to look out for? And what components can you tweak to adapt your gravel bike to the type of riding you plan?
Whether you’re on the lookout for a new gravel bike, or you’re looking to upgrade your current ride, we’ve demystified the intricacies of gravel bike setup to help you make the right decision.
Gravel bike gearing
That’s still a good option if most of your riding is a mix of tarmac and gentle off-road trails, and you’re not expecting to carry a lot of kit.
But hit a more technical off-road climb and you’ll likely end up walking once your rear wheel loses grip or you just don’t have the power to keep the pedals turning.
How low can you go?
With that in mind, the trend nowadays is towards much lower gearing for gravel bikes. In fact, as gravel bikes have grown in popularity, we’ve seen gravel-specific groupsets, such as Shimano GRX, and gravel-friendly gearing options released to accommodate the needs of riders.
With GRX, Shimano has introduced anti-slip hoods and a new lever coating to improve grip, while the leverage ratio has been adapted to improve braking on loose surfaces, moving the pivot point on the lever in comparison to Shimano’s existing road levers.
SRAM, meanwhile, has now released its Force eTap AXS Wide groupset, adding gravel-appropriate gearing to what is ostensibly a road groupset.
Many new gravel bikes will have gears that give you the lowest ratios of 1:1 or lower. That should let you climb steep, loose off-road ascents when unladen and also gives you enough range to load up your gravel bike for bikepacking excursions and multi-day trips.
The downside is that you may run out of top-end gears if you’re riding fast or descending on tarmac
It’s worth considering the type of riding that you’re expecting to do and where, when choosing a gravel bike or a new groupset.
The shift to lower gear ratios is driven by changes at both ends of the drivetrain.
At the front, there’s a trend to smaller chainrings, with super-compact chainsets increasingly specced (that’s where the chainring sizes are smaller than a standard 50/34t compact).
These are available in an array of smaller size combos: Shimano’s gravel-specific GRX groupsets give you a choice of 48/31t or 46/30t double chainsets and a growing number of aftermarket suppliers, including the likes of FSA, Rotor and Praxxis, sell gravel chainsets with similar-sized rings.
As well as lower ratios, a smaller chainring means that bike designers can more easily add clearance for wider tyres, supporting another trend in gravel bike design.
Meanwhile, on the back of the bike, the latest rear derailleurs can handle much larger cassettes, once again ensuring a wider range of gears for off-road riding and bikepacking
Whereas older rear mechs designed for road bikes might just about squeeze in a 30-tooth largest sprocket, many modern road rear mechs can handle 34, giving you a couple of easier gears for climbing.
Swap to a gravel-specific derailleur and you can head up to 42 teeth or so, although these wide range derailleurs are designed to work with single-ring groupsets, rather than double chainsets.
In terms of top-end speed, Shimano’s cassettes start at 11 teeth, but SRAM has options with 10 teeth on the smallest sprocket. Ten-tooth cassettes only fit SRAM’s XD-R freehub body though, rather than the standard Shimano/SRAM design.
To keep the chain taut over such wide ranges and aid chain retention, gravel-specific rear derailleurs will typically incorporate a clutch.
That’s always on in SRAM’s designs but there’s a lever on Shimano’s GRX and Ultegra RX derailleurs to let you release it when you’re riding on smoother surfaces. There’s a marginal decrease in drivetrain friction if the clutch is disengaged and it makes removing the rear wheel easier too.
1x or 2x?
The other trend in gravel bike groupsets has been the move to a single chainring setup, paired with a very wide range cassette, as opposed to a regular double chainset.
With a 1x groupset, you save a little weight by dispensing of the front derailleur, plus there’s less to go wrong and less chance of mud build-up. They are also designed to keep the chain in place and running smoothly when you’re riding over bumpy ground.
On the minus side, there are fewer gear options covering roughly the same gear range, so jumps between gears are larger. Gravel riders who spend a fair amount of time on the road, or covering ground quickly, might find the extra top-end range of a double chainset useful, too.
That said, once you take account of overlaps in ratios between the large and small chainrings in a two-ring setup, and unusable combinations at the high and low ends of the cassette, the actual number of unique gears isn’t that different.
A single ring setup means that you can access all gears sequentially too, rather than needing to swap chainrings to access your higher or lower ranges.
Because the chain doesn’t have to jump between rings, single ring chainsets have deeper teeth on the chainring to help keep the chain in place. Single chainrings usually have alternating wide and narrow teeth to match the different widths of the chain links, again to improve chain retention over uneven surfaces.
So deciding on a single ring and a double ring setup depends on the riding you’re planning. If you’re mainly wanting to ride fast on road and smoother terrain, a double ring chainset could give you a few more high-end ratios and smaller jumps between gears, while if you’re looking to tackle harder terrain, you may appreciate the chain retention benefits and simpler shifting of a single ring.
Want even lower gears? So-called ‘mullet’ builds mix a road chainset and shifters with a mountain bike rear derailleur and cassette for an ultra-low gear range.
Using Shimano’s electronic Di2 components, you can pair GRX shifters with an XTR or Deore XT Di2 MTB rear mech. Both MTB derailleurs can handle a 42-tooth cassette in double chainring configuration or 46 teeth with a single chainring.
It’s an option also promoted by SRAM with its new AXS 12-speed wireless electronic components. Here, the AXS Eagle MTB rear mech is designed to work with an Eagle 10-50t cassette, giving really low ratios when paired, say, with a 42-tooth chainring.
If you’re really into mix-and-match drivetrains, there’s a host of brands like Wolf Tooth Components that make parts to let you do pretty much whatever you like.
Over the last few years, gravel bikes have developed their own designs for wheels too.
The usual 700c wheel size for road bikes continues to be popular, but there is an increasing range of gravel-specific wheelsets, which typically have wider rims than a road-going wheel to provide better support for wider gravel tyres. Road rims are following fast in their wake and getting wider too.
Gravel bikes are invariably designed with disc brakes and rims are almost always tubeless-ready. The puncture protection afforded by the sealant in a tubeless tyre is a godsend when riding over broken surfaces and thorny debris.
Hookless rims are increasingly seen, where there is no lip to the rim edge. Hookless rims have been common in mountain biking for some time but are gaining prominence on the road and in the gravel scene too.
Alongside 700c wheels, many gravel bikes come with the option to fit 650b wheelsets. The smaller size – equivalent to 27.5-inch mountain bike wheels – lets you fit even wider tyres in your frame, with greater volume.
That adds comfort to the ride, as well as increasing grip on off-road terrain and letting you run even lower tyre pressures. With a large tyre, the rolling circumference of a 650b wheel is similar to a 700c with a narrow tyre, so gearing and handling should end up similar.
Rather like the single/double chainset choice above, which wheel size works for you depends on your objectives and what you want from your gravel bike.
For a faster ride on road and light gravel, you’ll probably want to stick to 700c wheels with narrower tyres of 40mm or less, while if you’re planning to head for more difficult terrain, you’ll appreciate the grip and cushioning offered by wider tyres on 650b, although that might be at the expense of speed on tarmac.
If your gravel bike has the clearance, a set of each wheel size would give you the best of both worlds, letting you swap between them depending on the ride.
Fitting the best gravel tyres for the riding you’re doing is another key decision for your gravel bike setup.
In fact, changing the tyres on a gravel bike can unleash the true potential of your machine, either significantly improving its ability off-road or adding a turn of road speed.
With gravel bikes used across such a wide range of terrain, it’s one area where you can easily change how your bike performs. We’d recommend tubeless tyres for gravel riding.
Gravel tyre width
Once you’ve settled on 700c or 650b wheels, tyre choice will largely be determined by tread pattern and width. If off-road grip and stability are important, look for wide tyres with a more aggressive tread pattern; if you’re more likely to be riding on the road or hardpack gravel, a narrower, slicker tyre will likely be more suitable.
700c gravel tyres are typically around 40mm wide, although you can get tyres that are wider or quite a bit narrower too. Typical widths are 35mm, 40mm, 42mm or 45mm. Have a look at this article, where we rode three different width gravel tyres from Maxxis, for an idea of the effect of tyre width on your ride.
How wide you go will largely depend on the terrain you ride and your frame’s clearance. If you live somewhere with a wet climate, it’s a good idea to leave some room for mud too.
Gravel tyre tread pattern
How muddy it is will also influence your tyre choice. In dry conditions and on finer gravel surfaces, you can usually get away with a file tread like the Panaracer GravelKing SK or a semi-slick design, with a smooth centre, like the WTB Byway.
The low-profile tread makes for fast rolling on tarmac, while there’s still enough grip from the side lugs to keep you upright and moving on looser surfaces.
If it’s wet or muddy, you’ll need something with more grip from a knobbly tread pattern. Schwalbe’s G-One range goes from the small knobs of the G-One Speed through to the G-One Ultrabite, while Continental offers the Terra Speed and Terra Trail for varying conditions.
There’s a whole range of gravel tyres from the likes of Panaracer and WTB designed for different terrain.
In wet or muddy conditions, large widely-spaced knobs can improve grip. The wide spacing will also help to shed mud. A tighter packed tread won’t work as well in wet conditions but will usually roll faster on tarmac or more hard-packed gravel surfaces.
For very muddy conditions, some cyclocross tyres are a good option too. At 32mm to 35mm wide (the UCI-limit is 33mm for racing, if you care), they’re typically narrower than gravel tyres.
This can sometimes help with grip as – in theory at least – the tyre can cut into the mud and down into harder surfaces, where a wider gravel tyre might float over it or clog. The narrower tyre also means that you’re less likely to get mud clogging your frame – handy if clearances are tight, which they often are on cyclocross bikes or older gravel bikes.
If you’re running 650b tyres, again there’s a range of gravel tyres with different tread patterns available, although there are fewer options than with 700c.
650b gravel tyres are typically (but not always) focused on high-volume options, so you’re more likely to find tyres with more aggressive tread patterns and in large sizes. These tend to start out at 40mm and head up to 50mm wide or more.
27.5in mountain bike tyres are also an option and may offer a deeper tread for more grip. Confusingly, MTB tyre size is often designated in inches rather than millimetres. You’ll want to check you’ve got clearance in your frame for some of the wider options.
Along with tread pattern and width, tyre pressure is a big determinant of how your gravel bike will handle.
The large air volume of wider tyres means that you can drop your pressure, giving you better traction, potentially lower rolling resistance and a more comfortable ride.
Giving a rough starting point for tyre pressure is a tricky business because it is so dependent on riding style, rider weight and terrain. However, as a guide, we would recommend around 40psi for a 40mm-wide 700c tyre, though you can usually drop below this. With a wide 650b tyre – something in the 45mm+ range – 35psi is a good starting point.
It’s worth experimenting with tyre pressure to see what works for your tyre choice and where you ride. Too high and you’ll get bounced around and lose grip, while too low a pressure may result in sloppy handling and extra pedalling effort, as the tyre squirms on the rim.
Tyre pressure that’s too low may also result in you bottoming out on the rim, if you’re riding on uneven surfaces. If you’re using inner tubes that might result in a pinch flat, but with a tubeless tyre that’s not a problem.
Experiment, take notes and think about investing in a digital pressure gauge. This will make future fiddling far easier, more accurate and, critically, repeatable.
Some gravel bikes come with flared handlebars, which are wider in the drops than at the tops. That means that you’ve got a bit more control when descending or riding hard off-road. It does cause the brake levers to sit at an angle though; the ergonomics can feel a bit awkward with a very wide flare.
Another gravel bike trend borrowed from mountain bikes is towards shorter stems. Whereas a road bike might have a 100mm stem, on a gravel bike this might drop to 70 or 80mm. That again helps with steering on awkward trails, as well as reducing the effective reach to the bars.
You’ll want a comfortable saddle too. There’s a benefit in having a longer saddle that will allow you to shift your weight around to tackle obstacles and descents, although quite a few gravel bikes now come fitted with stubby designs.
A growing number of gravel bikes are specced with dropper posts too, albeit with limited options. Some frames, however, will have ports to allow you to route the cable for an aftermarket dropper post, if you choose to upgrade.
Most gravel bikes have a 27.2mm seatpost and we’ve seen a number of dropper posts launched to fit that diameter. Shimano, meanwhile, offers dropper post compatibility with its GRX ST-RX810-LA lever, so you can use a dropper from the shifter, while SRAM also now offers dropper post compatibility with its Force, Rival and Apex 1x groupsets.
A dropper post lets you quickly lower your saddle, allowing you to shift your weight back and so it’s not in the way on tricky descents. However, it will add weight and complexity to your build, so is best saved for gravel bikes intended for use on properly technical terrain. Or there’s always a mountain bike.
If you’re going for an extended trip on your gravel bike, you may want to fit lights. There’s a huge range of different designs with different light intensities and run times available, and what works for you will again depend on your riding.
For off-road rides in the dark, a high-intensity mountain bike front light with an output of 1,000 lumens or more will give you good illumination, perhaps coupled to a helmet lamp to help see around bends in the trail.
That might be overkill when riding on a road and could dazzle oncoming vehicles, though the vast majority of lights will have multiple settings so you can dim output when required.
Battery life might be an issue too. If you’re on a long ride and want to avoid running out of power, some lights are compatible with a separate power bank or a second battery for a quick recharge.
For unlimited power, you could fit a front wheel with a dynamo hub to keep your lights charged as you ride. Dynamo lights are typically smaller than battery ones. Some gravel bikes have routing for the cable from the dynamo through the leg.
If you’re used to riding signposted roads, working out where you’re going on gravel tracks, bridleways, forest roads and trails may come as a bit of a shock. Even if you think you know where you’re going, conditions on the ground may make it difficult to choose the correct path.
A GPS bike computer is a useful accessory for gravel riders. Most mid- to high-end GPS units will have base maps that show some trails, although these are not always 100 per cent accurate. The more you spend on a computer, the bigger and more detailed the screen is likely to be – useful for navigating.
It’s worthwhile mapping out a planned route on software such as Komoot or Strava, uploading it to the GPS and following it if you’re unfamiliar with where you’re riding. That way, your computer can provide turn-by-turn directions or, if you do get lost, it should help guide you back to where you wanted to head.
If you’re going a long way or are on a multi-day bikepacking or touring trip, battery life might be an issue. As with your lights, you may want to carry a power bank or fit a dynamo hub to keep you charged up. A paper map is a good back-up to get you out of trouble.
Another typical feature of gravel bikes is lots of mounting bolts on different parts of the frame, letting you carry extra provisions and luggage.
You’ll usually get mudguard and rack mounts, although gravel bikes don’t tend to come fitted with either of these accessories as standard – they’re more likely to be found on commuting bikes and touring bikes.
There are usually mounts for a third water bottle cage on the underside of the down tube, upping your water carrying capacity if you’re going off-grid or allowing you to use a dedicated tool keg. Some gravel bikes will come with extra mounting bolts on the fork too.
Rather than a traditional rack and panniers, most gravel riders will use bikepacking luggage if they’re planning a longer expedition. That usually starts with a saddle pack and may include a bar roll and frame packs too. A gravel bike will sometimes have bolts at the front end of the top tube, letting you fix a feed box there.
The bottom line
The great thing about a gravel bike is its versatility; you can use it for everything from rides that are mostly on the road with a few sections of loose surface thrown in, to full-blown multi-day off-road excursions. The gravel bike that works for you will depend on where on that riding spectrum you fall.
However, there’s enough adaptability both in gravel frames and the range of components out there that you can easily swap out your kit and adapt your gravel setup to different aims and conditions. Expect to swap out tyres and possibly gearing for different terrain and seasons, and to fine-tune your spec over time to match your objectives.
To some extent, getting your setup right is down to getting out, riding and seeing what works for you – then, as you plan your next adventure, you can adapt your bike accordingly.