Wider tires offer more comfort and grip. But as the tire gets wider, the overall diameter also increases. This in turn means your chainstays get longer, the front-center gets longer, the steering slower, and in smaller sizes the headtube gets too high. In short, the bike feels less and less like a nimble road bike and more and more like a garbage truck.
So what you really want is extra width without much extra diameter and this is what the 650b wheelsize offers. A 650b wheel with a 47mm wide tire has the exact same diameter as a 700c road wheel with a 28mm road tire. So same diameter, but triple the air volume, comfort and grip by going to a 650b wheel with a 47mm tire. And if you go to 54mm as fits on the 3T Exploro bikes, the air volume is almost four times bigger and it still only has the diameter of a 700x40c tire.
Sometimes people say they want to stick with 700c wheels when they ride big tires because they want to "change as little as possible”. But while it may sound like sticking to 700c is changing less, in effect you are changing everything about how the bike fits and feels, while with 650b the rim diameter changes but the way the bike behaves remains the same.
In the quest for more comfort and grip, wider and wider tires are used on gravel bikes. While this offers mostly advantages, one drawback is that the tire flexes more sideways, making your bike less predictable in cornering. That can be solved by widening the rim.
However, a wider rim is also potentially heavier, and the rim width/tire width ratio has to be in balance to ensure proper seating of the tire on the rim. For the 650b tires with 47-60mm width that we use for the toughest terrain (and thus for which 650b wheels are the best choice), the ideal rim width is 28mm internal. Considerably wider than the 19mm more commonly found, but narrow enough that the weight is very low and the tire is perfectly secured on the rim, even without the need for hooks (as one would need for a road tire on a wider rim).
SEALTIGHT: Little-known fact: Most people are impressed if a new wheel spins endlessly. But it actually means the seals don’t make proper contact, so water, mud & grit can enter the bearings easily. Good (contact style) seals should feel stiff when new and need 100-1,000km of use to settle in. Not as sexy, but proper engineering.
SEALANT-RESISTANT: You may have heard of wheels destroyed by aggressive sealant. That’s why we use chrome-plated brass nipples (much more durable than alloy) with stainless steel washers & spokes. For best results, we recommend avoiding alkaline sealants with ammonia or sodium hydroxide.
DUAL FREEHUB: The Discus 45 | 32 wheelset comes standard with two freehub bodies: a SRAM xD-R freehub for both xD and xD-R cassettes as well as a Shimano freehub for 10/11speed cassettes. Use one, save the other and you will always be prepared for future changes and upgrades to your drivetrain setup.