Gravel Bikes & Adventure Bikes: A Buyers Guide

Whether you’re a gravel and adventure bike veteran or just learning about them for the very first time, this guide will cover all the key things you need to know before making a purchase. We’ll touch on:

  • What they are
  • How they’re designed; what makes them unique
  • Which features you can expect to find on Halfords’ range of gravel bikes
  • FAQ’s

Without further ado…

What is a gravel bike?

Gravel bikes are drop-bar bikes that are designed for off-road usage, such as on gravel, tracks, or paths, making them more versatile than your average road bike. They typically feature thick tyres which make transitioning between different surfaces more comfortable for riders.

These days, both ‘adventure’ and ‘gravel’ bike terms are often used interchangeably, with both of these bike types serving the exact same purpose. Some people think there are a couple of subtle differences, with gravel bikes originally being built more for off-road racing, whereas adventure bikes have always been known as durable, reliable off-road solutions for a wider range of consumer and are compared more to road bikes.

Gravel bikes originated from the US, where gravel-based surfaces are much more commonplace than you’ll find here in the UK, but typically you’ll find gravel and adventure bike product ranges merged into one these days and both types unlock the same opportunities for you as a cyclist.

Adventure and gravel bikes are perfect for use on gravel, tracks, paths, and any other type of off-road surface you can imagine. Now, let’s take a look at some of the design philosophy that make these bikes popular.

Gravel and adventure bike design

Here are some of the design features that are typical across all types of gravel / adventure bike:

Comfort based geometry

Most gravel and adventure bikes prioritise rider comfort over outright speed. A tall headtube combined with a slack head angle, helps riders adopt an upright position, something you’ll appreciate when riding long distances on and off road.

Long wheelbase

Continuing the frame design thread, gravel and adventure bikes tend to have a long wheelbase. A bicycle’s wheelbase is the measurement between its front and rear axle and increasing this distance helps spread rider weight, increasing stability. When braking, rolling over obstacles or dealing with changes in gradient, a long wheelbase also helps keep things the right side of the fun line!

Low bottom bracket

A low bottom bracket (BB) is another common gravel bike feature designed to increase the stability of a gravel bike. A lower BB means the rider sits lower on the bike, reducing their centre of gravity and subsequently helping the bike feel more planted.

Generous tyre clearance

Large tyre clearance is yet another concession made by gravel bike designers, increasing comfort and stability. Most models come shod with 32mm tyres but with room for much, much wider rubber. Extremely wide tyres are sometimes referred to as “monstercross” when they are similar in width to mountain bike tyres.

Disc brakes

Drawn by disc brakes' increased stopping power, easier modulation and reduced maintenance it’s no surprise to see bike brands use them on gravel bikes. Using disc brakes also frees designers from the shackles of caliper brakes – namely their impact on tyre clearance. Design a bike around disc brakes and it becomes easier for the frame and fork to accommodate wider tyres.

As with most bike types, gravel models tend to be unisex. By switching out contact points, or simply adjusting them, it's fairly easy to cater for riders of different shapes. That said, some brands do offer specific women's gravel bikes. Frame geometry and component selection is based around a rider of smaller form. And as another nod to the differing demands of female riders, the smaller frame sizes are more likely to run 650b wheels opposed to 700c. The theory here being that it helps maintain ride quality as well as reduce the chance of toe overlap when steering. 

Gravel bikes vs mountain bikes or road bikes: why choose a gravel bike?

Want to throw the in the odd bridleway on your favourite road loop? Don’t fancy going mountain biking, but like the idea of escaping road traffic? Dream of hopping on train for a weekend’s bikepacking? 

Love road and mountain, but only room for one bike at home? Hanker after a bike that can get you to work quickly Monday to Friday, before enjoying some off-road action at the weekend? 

Gravel bikes fit each of these scenarios and more!

Gravel bike features

Want to throw the in the odd bridleway on your favourite road loop? Don’t fancy going mountain biking, but like the idea of escaping road traffic? Do you dream of hopping on train for a weekend’s bikepacking?

Or, do you love roads and mountains alike, but only have room for one bike at home? Are you hankering after a bike that can get you to work quickly Monday to Friday, before enjoying some off-road action at the weekend?

Gravel bikes fit each of these scenarios and more, so hopefully these scenarios help you determine whether a gravel bike is right for you.

Frame & Fork

p>Gravel and adventure bikes come in a variety of frame designs, with each manufacturer having their own preferences. Some gravel bikes look very similar to road bikes and cyclocross bikes whereas others look a lot like a mountain bike that’s been fitted with a set of road handlebars.

Gravel and adventure bikes are designed to be light and manoeuvrable, which makes riding on and off-road an awful lot of fun. The frame shape (geometry) will differ from a traditional road bike, with a sloping top tube inspiring more confidence when riding on technical tracks and uneven surfaces.

See detailed information below.

Suspension

A gravel bike with suspension? Are you sure? Yes! Suspension is one of several attributes used to distinguish certain gravel bikes from one another. Most designs involve the use of shock absorbing materials or elastomers in the frame to soak up the bumps, with more extreme models running a front suspension fork, albeit with less travel than a traditional mountain bike. If you’re going to spend more time off road than and on, or if you’ve a penchant for exploring the edge of grip, then a gravel bike with an element of suspension will be for you.

Dropper Post

Dropper post on a gravel bike? Again – are you sure? Yes, yes we are! As off-road descents get steeper and more technical, the more a rider needs to shift their weight over the rear wheel and lower to the ground. A dropper post scoots the saddle out of the way enabling the rider to tackle the descent with confidence. Whilst they’re not a common feature of gravel bikes today, we can certainly see them becoming more popular in future!

Frame Mounts

Gravel and adventure bikes are the perfect partner for bikepacking trips. If you’re buying something to go on this kind of trip it’s a good idea to take stock of your chosen model’s frame mounts. Three bottle cage mounts are perhaps the bare minimum for water carrying requirements. And if you’re going to be using an extra-large frame bag which covers the traditional bottle cages, look for a bike whose forks include mounts too!

Wheels and tyres

Gravel and adventure bikes roll on standard 700c road wheels that you find on most road bikes and 650b (27.5”) wheels you will find on mountain bikes. You can also find gravel bikes with 29” wheels too.

As a rule of thumb, if you’re wanting to spend more time off-road than on it, go for a bike with 650b wheels. If tarmac is more to your taste, then we recommend you choose a bike with 700c wheels.

Some gravel bikes are compatible with both wheel sizes, which means you have the option to swap wheels as often as you like.

See detailed information below.

Wheel sizes

Gravel bikes roll on one of two wheel sizes. Most use standard 700c road wheels, with some using the 650b (27.5”) standard. Teaming a 650b wheel with 47mm tyre is the equivalent of running a 700c wheel with 30mm tyre but with the added benefit of an increase in contact with the ground. A very general takeaway here: if you’re after comfort or traction off road, plump for a gravel bike with 650b wheels and if tarmac is more to your taste a 700c wheeled bike will suit.

Thru-Axles

The majority of gravel bikes uses thru axles. Stronger and less prone to flex over rough terrain than quick release skewers, they’re also less likely to accidentally come loose whilst riding. A rough standard has been set, with most models using 12x142 rear and 15x100 front. The first number refers to the diameter of the axle with the second denoting the dropout width. If upgrading components in future is important to you, do take a note of a bike's axle size

Tyre clearance

To keep your riding (and tyre) options as open as possible it’s a good idea to find out each gravel bike’s maximum tyre clearance before buying. It’s easy enough to pop a pair of 28mm or 30mm road tyres on if the tarmac is calling, but if a big adventure ride calls for 42mm tyres and your bike can only take 37mm you’re going to be snookered! Be aware that sometimes the measurements provided on the tyre might have a margin of error – true story!

Tubeless

Very much in vogue right now, a tubeless setup promises an increase in puncture protection - thanks to the sealant, more squish - thanks to an ability to run lower air pressures as well as a faster ride – thanks to lower rolling resistance. If running tubeless is important to you, be sure to choose a gravel bike with tubeless compatible wheels and tyres.

Disc Brakes

Ploughing through muddy terrain, slowing on a steep descent, or pulling up short of an obstacle – gravel riding calls for disc brakes – simple! At the lower end of the market, you’ll observe that bikes run mechanically operated brakes, whilst more expensive bikes are equipped with hydraulic disc brakes.

Mechanical, or cable operated, disc brakes don’t offer the best braking feel (modulation) but are much easier to repair road or trailside when compared to hydraulic brakes – ideal then if you’re on a multi-day adventure ride. As well as offering the best braking performance, hydraulic disc brakes usually require very little maintenance once setup correctly.

Gearing

As road bikes continue to hold onto their double chainring gearing (2x) – gravel bikes have jumped into 1x with both feet. A 1x drivetrain consists of one single chainring upfront and 10,11 or 12 sprockets on the cassette at the back. A typical cassette pattern for a gravel bike is 11-42. That largest cog will quickly become your best friend if you intend to tackle steep off-road ascents on a gravel bike. Think you’ll be spending more time on hardpacked surfaces where riding speeds are higher? A bike with a tighter cassette ratio, say 11-32 and maybe a 2x chainset up front would suit you better.

Most gravel bike gearing uses a mechanical process to initiate a gear shift. Got deep pockets? As in mountain biking and road riding, electronic gear shifting is becoming more ubiquitous. Shimano’s Di2 and SRAM’s AXS groupsets promise reliable, easy gear shifting along with the possibility of multiple shift buttons, easy calibration and customised integration with other bike components.

Handlebars

Browse our selection of gravel and adventure bikes, including Boardman adventure bikes, and you might see that some models include a flared handlebar. Flared refers to the way the curve of the ‘bar moves outward, as well as around in that inverted C shape. Flared bars help handling on rough terrain whilst also allowing for easier placement of a handlebar bag – a bag perfect for single or multi-day bikepacking adventures.