After 217 kilometers my new wheels have proven that 650B is my ideal road and gravel size. I made this discovery with my third Volagi Viaje years ago already. But for the last two years, I rode my latest bike, my Nordest Albarda, on a set of 700C wheels. Such wheels roll well, but they don't like to change direction as quickly as a smaller 650B wheel. I like a bike to be lively and agile. Directional stability can have its advantages, but I generally prefer quick, sharp steering. Switching my Albarda to smaller wheels, instantly gave me that. The bike is so much more fun to ride. Not just when going downhill, but when climbing as well. When riding up a climb out of the saddle, it always seemed like the 700C front wheel was working against me. After putting 650B wheels on the bike, that feeling is gone. The bike now is a better extension of myself when motoring up a climb out of the saddle.
At speed, the wheels and wider tires are an absolute treat. They smooth out everything. Rather than feeling road vibrations, it feels like sitting aboard a hovercraft. Most riders equate vibrations with speed. Narrow, hard tires transmit all the road chatter to the rider. So, when we feel the road more, we believe that we're going faster, even if the speedometer says otherwise. Separate your body from such vibrations, and you suddenly think that you aren't all that fast, even if the speedometer may say otherwise. I have yet to put enough miles on the bike to figure out how the 650B wheels affect my average speed. And this year isn't representative anyway. I'm unable to train nor rest as much as in the past.
I was probably one of the first Swiss riders to move from 26" to 29" wheels in 2006. I lived still in the US when I bought my first 29er but had already set things in motion to move back to Switzerland. I was long an advocate of the "bigger is better" movement. Interestingly, now that the 29" wheel has become the de facto standard from XC to downhill, I find myself moving away from the trend. I own two 650B road bikes, a 27.5" fat-bike and I just put a down payment on a 27.5" mountain bike. There are some interesting months ahead, as I need to shop for components. The frameset should be arriving sometime in August.