The Verdict: 650b & Road Plus

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3-minute read

If you’re a cycling vet, you’re aware that 650b is the wheel size du jour.  It’s also called 27.5”.  For those of you that haven’t heard, it’s about halfway between the diameter of “old” 26-inch wheels mountain bike wheels and 700c or “29er” wheels.  While it’s actually not a new size to cycling, its reintroduction is relatively recent.  I’ve covered the topic quite a bit over at Slowtwitch – here, here, and here

What I haven’t seen, however, is a recap and verdict on the topic of 650b wheels for bikes featuring drop bars (gravel, cyclocross, and “Road Plus”) – at least not the one that I think needs to be published.  I’m a big-picture guy, and want to know big-picture things for the industry – and what it means to the average person who rides a bike.  I’m not talking to you dedicated high-performance racers that schedule your life around two-wheeled optimization.  Those folks know what they want, and are willing to invest the time and money to test the newest iterations of equipment. 

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No, I’m talking to the busy people with families, jobs, and other interests – for whom cycling is on a level playing field with many other priorities.  If you’re one of those guys or gals, is 650b all that it’s cracked up to be? 

In short, yes and no.  650b won’t radically change your cycling, especially if you already own a cyclocross or gravel bike with standard 700c wheels.  The idea with 650b / Road Plus is that you use a smaller diameter wheel with a very large tire (often about 47mm+ wide), which gives you an overall tire diameter that’s comparable to a 700c road or gravel tire.  The purported advantage is that the 650b tire is much wider and cushier, to help you navigate very rough terrain and soak up bumps. 

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Does 650b set out what it’s supposed to do?  Yes, mostly.  The tires are big and meaty, and allow for very low pressures that are great for off-roading, gravel, and broken pavement.  Most 650b-capable bikes also allow for 700c wheels and skinny tires to be used, giving you a lot of options in a Swiss-Army-like package.

Here’s the fine print that they don’t tell you.  650b and “Road Plus” bikes are in a strange middle zone.  They can’t quite do what a mountain bike does.  The fat tires roll slowly and can’t quite keep up with a fast road ride.  You can change out wheels and tires to help your cause, but that takes time (compounded by the fact that changing wheels on disc brake bikes almost always require brake adjustments).  For the serious cyclist these are acceptable compromises, but for the time-crunched person hoping to squeeze in an hour ride after work, it could easily sap 15 or 20 precious minutes.  I suggest being realistic here and opting for simplicity.

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The other thing I learned after many months on my 650b-equipped Surly Midnight Special was that it didn’t really feel much more capable or comfortable than the many 700c-equipped bikes I’ve owned.  If you pump the tires up high enough to roll reasonably fast, they aren’t any more cushioned than a 700x28 or 700x32 road tire.  The wide 650b tread didn’t really feel more secure on rough stuff than a 700x35 or 700x40 gravel tire.  It’s a jack-of-all-trades that looks cool and is fun on really crappy pavement, but generally just feels slow.  In other words – if the terrain is bad enough to “need” 650b, you’re probably better off riding a mountain bike with suspension.

The other issue with 650b is that it suffers from Early Adopter Loneliness Syndrome.  If you’re the first person in your ride group to own one of these, who are you going to ride with?  It’ll be tough to keep up with the road group unless you’re exceptionally strong, and you’ll have a heck of a time keeping up with mountain bikers on legitimate trails.  I had the same problem when I was an early adopter of fat bikes.  None of my friends had them.  I could ride in the winter snow and ice, but I had to ride by myself.  It took several years before I found anyone to join me.  The only place I see 650b having a speed advantage is if you have a group gravel ride with some particularly gnarly or loose sections (and the conjones to bomb through it on fat tires).

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I suppose the biggest takeaway is that 650b isn’t inherently bad.  If you’re shopping for a new bike, there’s no reason to avoid a bike with 650b capability.  If, however, you already own a 700c-equipped cyclocross, gravel, or touring bike – I don’t think it’s worth “upgrading” to a 650b bike.  There’s also a current downside of 650b being so new that tire selection is relatively slim – especially when you look into specialty items like studded tires. 

The place that 650b doesn’t get enough credit is in its utility for smaller riders, when coupled with smaller diameter tires (i.e. 32-42mm).  Surly was first-to-mass-market here (again) with their 650b Straggler, first available only in sizes for short riders.  Shorter riders benefit from smaller wheels, and 650b is now the only fashionable choice, after the industry decided that 26-inch and 650c wheels were dumb.  If you’re under about 5’6”, this is exactly the type of bike I suggest shopping for.

Personally, I have enjoyed my 650b bike as a learning experience.  It’s cool and hip and does what it says… it just doesn’t feel fast or fun unless the going is VERY rough (but some of those cases had me wishing for a mountain bike).  If I had to really carve out a niche for it, I’d call it the perfect commuter bike for someone that lives in a place with bombed-out streets (i.e. Detroit) or tons of rail crossings in your path (i.e. San Francisco).  I’ll eventually sell my 650b bike, as I’m already planning my next project bike (duh) – but I hope these insights help some of you out there make good decisions and avoid wasting money.



Wolf Tooth Tanpan 11-speed:

WTB Horizon 650b x 47mm tires:

Thomson Elite seatpost:

Cane Creek 40-Series tapered headset (note: reducer crown race is needed for the Midnight Special fork - sold separately):

Selle SMP Avant Saddle:

Shimano Ultegra 6800 11-speed shifters:

Shimano Ultegra 6800 11-32 cassette: