Advantage of a Mountain Bike With 650B Wheels

650B Mountain Bike
tomascosauce/Flickr/CC BY-SA 2.0

A mountain bike with 650B wheel/tire size fits right in between the other two readily available mountain bike wheel sizes, 26" and 29". The 650B wheels measures at about 27.5", and much like 29" mountain bikes, this intermediate size is growing in popularity. The standard 26" wheel, the most popular for many years, is undergoing challenge these days. 

Why Wheel Size Matters

There has been a lot of recent debate about wheel size in the mountain bike industry. On the one side, there are mountain bikers who firmly believe that 26" is the optimal size. Challengers, though, are now of the opinion that we came to our current standard of the 26" wheel somewhat arbitrarily. The standard of the 26" wheel size was established long before mountain bikes came around, and the assumption that this is the optimal size for mountain bikes may be a fallacy.  

On the other side, a similar argument—and similar criticism—exists for the group that swears by the 29" wheel size.

You might wonder why the industry cannot seem to make up its mind on the issue. It is just a matter of cost. It is very expensive for the industry to convert to new tooling for different size tires and wheels, so there is strong incentive to stay with whatever system you are currently using rather than change. 

Then there is the establishment issue. Nearly all of the advancements in mountain bike geometry and technology have been based on 26" wheels. If you arbitrarily change the wheel size, you run the risk that the old established standards with 26" wheels will no longer work. As with most engineering problems, there are both positives and negatives to almost every option. So, new design optimization may need to take place each time wheel size changes—a strong incentive to stay with the status quo.

The Argument for 650B

The people behind the 650B movement claim that with 650B tires you get all of the same advantages of the 29" movement (lower rolling resistance, better traction, smoother ride, etc.) with less of the disadvantages (geometry limitations, toe clearance issues, higher center of gravity, suspension travel limitations).

Much of this may be true, but individual bikers are advised to test out a bike built to new standards and make sure it provides tangible benefits to them before going out to invest in a 650B bike. 

The 650B movement is clearly gaining traction, however. Some manufacturers of forks are now giving the okay to run 650B wheels in their standard 26" forks. This concession, and others like it from manufacturers of other bike components, may take the 650B movement a long way down the road to broader implementation. 

Change Comes Slow, But It Does Come

It's unlikely that the entire mountain bike industry in mass will immediately change their standards and convert their manufacturing processes to favor 650B bikes as the overall favorite. Too much is invested in the 26" wheel for it to go away anytime soon, and the 29" crowd also is a vocal one. It may be a long time, if ever before the entire industry settles on a single wheel size that serves the mountain biking community best. But the bike industry will likely learn some lessons from this debate, and already it's evident that riders now are enjoying enhanced options for different sized riders, and for different types of riding.

The 650B's purported benefits—all the speedy acceleration and nimbleness of 26" wheels, combined with the smooth rolling and enhanced traction of 29" wheels—are reported to be very real by experienced bikers. It's is very likely that more 650B bikes will be available to riders in the future, and whether it becomes the most popular type will ultimately be determined by the consumer. 

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