Wait, there’s different wheel sizes? So many options these days. But there’s a good reason for so many choices as it gives riders a chance to customize their ride and riding experience. Don't despair, we’ll boil this down to the key considerations so you can decide what is best for you.
If you’re a road rider you probably have never thought much about wheel size and for good reason. With a few exceptions, 700c road wheels have been the standard for quite some time. But what if you’ve started to look at the world of gravel riding? Over there on the off-road stuff you’ll also find another wheel size, the 650b. This smaller size offers an alternative set of properties and performance benefits. Pairing smaller rims with wider tires can transform how a bike rides especially when you want to go fully off-road or you like the cushy feel of a big tire. So what's the best gravel bike wheel size?
700c: If You Need Speed
If you’ve been riding road bikes, 700c wheels are likely the wheels you’re most familiar with. With a large diameter rim, they were designed to roll fast. With knobby or siped tread of gravel tires, and a smaller contact patch that rolls faster over graded dirt roads, 700c gravel wheels were designed to do the same: provide efficient speed over gravel roads.
The one aspect that everyone always talks about is good old rolling resistance, or ideally, the lack of resistance. So technically, a larger wheel should roll smoother and faster for a set distance. Because it’s a larger diameter it will carry more momentum as well, so it should keep you rolling further and should maintain speed better than a smaller wheel.
If we’re considering going off road, a larger wheel can help you tackle the obstacles. We only have to look at the world of mountain bikes where riders pick the larger 29er wheel as it rolls better over obstacles than the smaller 27.5″ or the classic 26” wheel.
Because the larger wheel fits deeper into the frame’s chainstays and seat stays in the rear of the frame (and within the fork blades on the front), frame and fork clearance limitations do put a limit on the size of tire you can use. As a result, most 700c wheels on gravel bikes can accept tires anywhere from a 25mm road tire (more on that later) to upwards of 42mm (up to 50mm on the Cobalt Warhawk). As you go up in tire size, you get a greater tire contact patch with the ground, more traction, the option to run lower tire pressures, and the larger tire provides more shock-absorbing cushion in rough sections.
700c wheels are also highly versatile; while you can run high tire pressures in 700c wheels for speed, capable of easily handling most every condition but really shining when race day brings one priority: speed. Ride an equal split of dirt and pavement, or like to simply hammer on the weekends with your friends—and of course hammer on race day? 700c is your wheel of choice. We’ve made this easier for you because the Warhawk and Marauder both fit rather large tires so you can get the best of both worlds.
700C Characteristics: larger wheel, faster momentum, option to run smaller higher pressure tires. Great overall choice for weekend hammering and racing
650b: Comfort and Handling
Running a 650B wheel puts a whole other gravel riding priority set forward: comfort and improved handling.
There are a few advantages for a smaller wheel size. Smaller wheels accelerate faster than a 700c, so your bike will get up to speed quicker than one with larger wheels. So it technically should be faster from a standing start. You can also run larger tires, giving you more tire patch on the ground and improved traction and you have the option to lower tire pressure for a cushy feel or to absorb those rough patches on the road or trail.
With its smaller diameter, 650b wheels share more in common with today’s mountain bike wheel. With that smaller diameter comes the ability to run a much fatter, more plush tire, from 40mm up to 50mm (2.1 inches). With a bigger tire comes more contact patch, option for bigger tread, and greater traction. When things get muddy, sandy or steep, bigger tires (on a 650B wheel) can simply handle the tough stuff much easier, especially at low speeds. It’s not to say 650b is a slow wheel by any stretch. Rather, you simply sacrifice some of that top-end speed capability that 700c wheels often enjoy.
By the nature of its size, a smaller diameter 650b wheel can turn tighter corners and make quick balance adjustments with great ease, thus making it a great choice for those riding technical courses. And, when matched with a standard road groupset, the smaller gear ratios in the smaller 650b wheel delivers even better climbing gearing. Do you prefer to ride slower, explore and just play around on the bike, and not focused on races? 650b is a great choice.
Are you a smaller rider? For riders under 5’ 6” or so, a bike outfitted with 650b wheels is a good choice. From a low-speed handling standpoint, the bike can maintain better handling characteristics; the bike is more “underneath” riders than out front. Also, while most small riders have problems with toe overlap with their front wheels while steering at low speed, a bike outfitted with 650b wheels can navigate in the same way without risk of excessive toe overlap. The 650b wheel also lowers the top tube so there’s more clearance for standing over the bike while stopped.
Bikepackers also enjoy 650b wheels. With a greater degree of all-day-riding compliance using a wheel with larger tires, eight hours in the saddle with a bike loaded with bags on bumpy trails goes by more comfortably with a bigger tire providing cushioning to your ride.
650b Characteristics: Smaller diameter rim, room for larger tires, great choice for comfortable all day riding, riding the singletrack on your gravel bike, or bikepacking over rugged terrain with improved handling
The Case for a Spare Road Wheelset
With that in mind, we do make a small suggestion to consider: having a spare wheelset with slick tires, as well as a matching road-specific cassette, like an 11-28T. 700c or 650B doesn’t matter much. What it does is provide you the ability to enjoy your bike on the road. Sure, you can ride your gravel tires on the road, but when your friends are out for the group coffee ride, your Cobalt bike can be magically transformed into a speedy road machine, without the hindrances of a wide, treaded tire slowing you down on the pavement. (Sure, you can simply change the tires on your one wheelset, but if you’re running tubeless with sealant, do you really want to be switching tires back and forth? We don’t either.)
The wonder of gravel riding is that it can be anything you want. With a choice of 700c or 650B wheels, that choice can truly tailor to the riding experience you seek. Of course, if you have any more questions about which is the right choice for you, the terrain you ride, and your gravel riding goals, our team is always here to help you make the right choice.
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