I can understand your reluctance. I had the same concerns before I built up my 650b specific Kogswell P/R with Hetres. But after I rode the bike. Wow. Just wow.

Like you, I read review after review about how great thes tires are. And I finally came across my Kogswell frame that was designed for 650b tires, so I took the plunge:



Equipped like she sits in this photo... complete with double leg kickstand, dyno lighting, frame pump, and huge honkin' porter rack... the bike weighs exactly 30 pounds. Not exactly a lightweight.

But it rides like greased lightning. And smooooth as silk. This bike really surprises people... they're not used to seeing a fat tire bike cruising so fast. I've had more than one person comment on how fast the bike feels... and last Saturday at my LBS I had a line of employees and customers waiting to take a test ride on it... and 3 people tried to buy it from me on the spot!

But keep one thing in mind:
If you're building a bike around these specific tires, then go all the way with your wheelset. The tires will not be stellar if the rims, hubs, and spokes are trash. I built my wheels myself with Velocity Synergy rims, DT Swiss Revolution spokes, alloy nipples, SON front hub, and Shimano XT rear hub with SRAM PG990 cassette.

These wheels are light. Insanely light for a wheelset built for a 42mm tire. But they make the bike leap forward when you stomp down on the pedals. And smooth. Did I say smooth yet?

Riding these huge fast tires is unlike anything you've ridden before, but the oddest thing about them is the sound. Yes... the sound that they make. You know the echo type of sound that a kid's kickball makes when you thump it? That hollow balloon echo inside of the ball? Well these tires make that that noise, but it's constant. You can hear it when you're out away from traffic and everything is quiet. It's a ballooney thrumming sound as the tires roll across the pavement... very comforting to me... kind of neat. It's not a loud obnoxious sound... just a comforting background hum that you hear when it's quiet around you.

I'm glad I drank the Kool-aid. As a matter of fact, I'm considering putting 650b wheels on my Surly Pacer now. She weighs 21 pounds ready to ride with 700x23C wheels. That bike ought to be really fun and fast with some Pacenti Parimoto 38mm tires on it. Most of the reviews I've seen say that those are some of the fastest 650b tires that you can get your hands on!