700c vs 650b: Which wheel size is best for gravel and bikepacking?

As the only point of contact between bike and the ground, wheels are one of the biggest influencers of how your bike feels and performs. For gravel riders and bikepackers dialling in their setups, wheel sizes matter. While sizes haven’t changed dramatically over the years, they do go by a few names. What those names actually mean and how they work with modern gravel and bikepacking bikes however, isn’t always so obvious.

In this guide, we break down the differences between 700c and 650b wheels, using real-world riding examples to show how each performs and help you choose the wheels that best suit your riding style and the adventures you have planned.

Local loops on rough back lanes or a multi-day journey pushing the boundaries of what’s rideable on a drop-bar bike, the wheels you choose play a starring role in what both you and your bike are capable of.

Modern gravel bikes typically deal in two wheel sizes: 700c and 650b. Each determines the tyre widths you can run and the overall wheel diameter, directly influencing speed, comfort, traction and terrain suitability. Choose wisely and a different wheel size can unlock a range of distinct ride characteristics, shaping how your bike feels and performs across different surfaces.

While the French origins of 650b lie cycle touring, in recent years, thanks to the rise of gravel and adventure riding, there’s been a resurgence in 650b wheelsets, favoured for their ability to run larger tires while maintaining a manageable overall wheel size. 

So what does the 650 refer to? The idea is that including the tyre the total diameter of the wheel will be approximately equal to 650mm – though this will of course vary dramatically according to the tyre size and profile. The reliable measurement then that we can be definite about is the bead seat dimeter (BSD) – meaning inner edge of the rim, where the tyre’s bead hooks on. For 650b wheels, this measurement is always 584mm.

The “b” comes from the French sizing system, in which the letter referred to the tyre’s width category rather than the wheel’s diameter. Those lettered sizes became inconsistent over time, so modern bike standards now rely on measurements provided by the International Organisation for Standardization (ISO). Today, “650b” is the common name for the ISO 584 wheel size, measuring the same as a 27.5 inch mountain biking wheel.

Key 650b wheel specs: 

• Bead seat diameter: 584 mm 
• Typical gravel tyre widths: 38–50 mm  
• Alternative names: 27.5 inch, ISO 584 

The universal standard for riding on the road is a popular choice for gravel bikes too. The measurements follow the same format as for 650b, meaning that for 700c wheels, the overall diameter – including the tyre – is approximately 700mm, while the BSD is always 622mm. Similarly too, the “c” refers to the widths which were once more standardised, designed specifically for thinner tyres.

Key 700c specs:

• Bead seat diameter: 622 mm
• Typical gravel tyre widths: 32–45 mm
• Alternative names: 29 inch, ISO 622

The numbers are useful, but what really matters is how these variations influence things like rolling efficiency, comfort and stability or your bike’s handling when you’re tackling rough, technical trails, loaded with bikepacking gear.

At a glance, the differences between 650b and 700c wheels come down to how they balance speed, stability and comfort. 650b wheels sit slightly lower, lowering the centre of gravity and allowing the use of higher-volume tyres that improve stability and absorb vibrations.

Their smaller diameter also means less rotating mass, giving a more responsive, snappier feel when accelerating or changing pace, while shorter spokes build a more durable wheel build. 700c wheels, by contrast, use a larger diameter that pairs best with narrower, higher-pressure tyres, helping maintain speed efficiently on smoother surfaces – though this can result in a firmer, more direct ride feel on rough ground.

A 650b wheelset can make a gravel bike feel easier to control, which can be especially beneficial for smaller riders, but its advantages extend well beyond. One of the biggest draws of 650b is the ability to run wider, more aggressively treaded tyres, bringing clear benefits in grip, stability, comfort and durability.

By opting for 650b wheels, you can often make full use of your bike’s tyre clearance, unlocking several extra millimetres of width compared to a 700c setup. This added tyre volume is a real advantage on rough, rocky terrain or long, demanding off-road routes, where comfort and control matter most. Importantly, it achieves this without significantly increasing overall wheel diameter, helping preserve the bike’s intended geometry and handling.

There’s a reason 700c wheels are the standard across road bikes, and they remain a popular option for gravel bikes too. If your riding tends to be faster and more efficiency-focused, incorporating road miles or hard-packed, fast-rolling gravel, 700c wheels are the natural choice.

The larger wheel diameter pairs well with narrower, less aggressively treaded tyres, helping you carry speed more easily and maintain momentum over longer distances. This setup delivers a ride feel and handling characteristics that are closer to a traditional road bike, making 700c wheels particularly appealing for riders who prioritise pace and rolling efficiency on mixed but relatively smooth surfaces.

Comfort on gravel is all about tyre volume. Wider tyres hold more air, allowing them to absorb bumps and vibrations before they reach the rider, while the larger contact patch also improves traction on loose or uneven surfaces.

Tyre pressure on your gravel bike then lets you fine-tune that comfort. Lower pressures increase shock absorption, smooth out chatter from gravel, roots and rocks, and reduce fatigue on longer rides – benefits that are even more noticeable when riding loaded with bikepacking gear. With narrower 700c gravel tyres, however, how low you can go is limited before damage to the rim become a concern.

This is where 650b comes into its own: a 650b × 48 mm tyre can match the overall diameter of a 700c × 40 mm tyre, yet deliver a smoother, more controlled ride thanks to its greater air volume and ability to run lower pressures safely. Running tubeless tyres will exaggerate this even further.

As a starting point, use the pressure range printed on your tyre sidewall and begin near the middle. From there, adjust based on rider weight, terrain and riding style. Heavier or loaded bikes generally need slightly higher pressures, while lighter riders and rougher terrain allow for lower pressures. Small changes can make a big difference, so experiment to find the sweet spot between comfort, grip and protection that works for you.

Most modern gravel bikes are compatible with 700c and 650b wheelsets, meaning you can alternate between them for different types of rides. Before changing wheels or tyres though, it’s important to understand the compatibility limits of your bike’s frame and how changing the wheels can reshape the bike’s geometry and, with it, the way the bike handles.

• Clearance: Commonly referred to as frame clearance, every bike is designed around a maximum tyre size, determined by the available space inside the fork blades, seatstays and chainstays.
• Brake compatibility: Disc brake placement is fixed on the frame and fork, so any wheelset must match the correct hub standard and rotor size. While swapping between 650b and 700c typically doesn’t require different rotors, some bikes are optimised around a specific rotor size, which can influence braking feel and heat management when changing wheel and tyre setups.
• Gearing: Changing wheel diameters effectively changes the gearing. Although the difference is relatively small, riders who regularly swap between wheel sizes should account for this when choosing chainring or cassette sizes to maintain their preferred gearing range.
• Bottom bracket height & pedal clearance: Larger wheels or higher-volume tyres increase the overall rolling radius, which raises the bottom bracket and lifts the bike’s centre of gravity. While this can improve pedal clearance and rollover on rough terrain, it can also make the bike feel less planted when cornering or negotiating technical sections, particularly at lower speeds or when carrying loads.
• Head tube angle & steering feel: Lifting the front of the bike also slackens the head tube angle and lengthens the bike’s wheelbase. This combination delivers greater straight-line stability and a calmer feel at speed, but steering becomes slower and less responsive in technically demanding terrain. Conversely, smaller wheels or lower-volume tyres reduce rolling radius, lowering the bike and steepening the head tube angle.

The key thing to remember is that every bike is designed with its own geometry, features, and ride characteristics in mind. Canyon gravel bikes are designed around both 700c and 650b wheels, depending on frame size and intended use. While 700c wheels are the standard choice on most Grizl and Grail models for fast rolling and efficiency on mixed terrain, smaller sizes may use 650b wheels to allow for wider tyres, increased comfort, and consistent handling. This approach helps ensure every rider benefits from the intended ride characteristics, regardless of frame size.

Choosing between 650b and 700c wheels ultimately comes down to how you ride and where your gravel adventures take you. When making your decision, it helps to step back and consider a few key factors:

• Terrain analysis: What kind of surfaces do you ride, smooth roads and hardpack gravel or rough gravel and technical trails?
• Riding goals: Do you prioritise speed and efficiency or comfort, control and adventure?
• Rider skill level: Be realistic with your ability – are you comfortable riding fast over technical terrain or is control and stability more important?
• Future needs: What are your aspirations on the bike, do you want to race gravel or explore on bikepacking adventures? 

If your rides lean towards mixed terrain and fast gravel with a focus on efficiency, 700c wheels are likely your best match. Venturing into rough, technical terrain, 650b wheels can make a tangible difference, with wider, higher-volume tyres adding comfort, grip, and stability, inspiring confidence when you need it most.

At Canyon, our gravel bikes are designed for both 650b and 700c wheelsets, ensuring each delivers the handling, performance, and versatility it’s intended for. To find the setup that suits you best, check out our gravel bike buying guide, use the bike comparison tool, or try the bike finder to narrow down your options with confidence.

Whichever you choose, 650b or 700c, the right combination of tyres, pressure, and setup will unlock the door to new adventures, getting the most out of your time on the bike, whatever that means to you.