The "croissant" is a work bike, I just added a picture to the web-page showing a picture of my work rig.
As a work bike it does not get the care and attention it deserves, so little things like over-long cables do not get attended to. But I do love my front rack with a set of panniers, it just lets me haul things without a backpack or a bumbag. Yes, it can affect handling, but in the case of this bike, the weight seems to improve it handling, making it less twitchy.
After riding the 650B for about a week, I am very impressed. I thought at first that it slowed me down (increased rolling resistance from the fatter tire), but it is not true. It feels like you are going slower because you fell less road noise because of the softer tires. I do not ride with a speedometer, but since I have regular routes that I run, I know how long it takes me to get from A to B. And my times have stay the same or dropped on all routes. So the myth that a 650B is slower is not true.
The biggest thing I like about the 650B is the comfort. I was running a 35mm tire (Schwalbe 590x35) before but unless I kept the tire aired to at least 80psi, I would bottom out on bumps. But with the new wheels and tires (Panaracer CdlV 584x38), I have yet to bottom out and I am only running 50psi. This alone is enough to convince me of the superiority of 650B. Alex Wetmore has taken me to task on this statement and believes this increase in performance is a function of the tire not the 3mm decrease in rim radius. Since the Panaracer CdlV is available in various wheels sizes, I am going to run a direct comparison and see what part the tires and the rim size plays in the 650B phenomenon by running the identical tire on different rim sizes.
I have found that a regular 26x1.90 MTB tube works fine with the 650B, so finding suitable tubes is none issue. There is a lot noise at the moment about the new 650B tire that Jan Heine is bring in from Japan, the Grand Bois "Cyprès" 650B x 32 mm, not a 23mm tire but it is a bit thinner than the standard 650 issue.
Is the 650B a miracle wheel size? No I am sure I will find a few warts as I gain more experience with it, but I do believe it offers viable and real benefits to a cyclist who is looking for high performance and comfort.
P. Lynn Miller
There's also something (I don't remember high-school physics well enough) about the smaller wheels putting out more force keeping the bike upright. Because this force is related to the speed of spinning, not the size of the wheel (and smaller wheel spins faster). I think this is something related to "twitchy" issue as well. But I haven't really thought this through or figured it out. But of course there's some miny-max situation as the wheels get really small. But 650 may be more optimal than 700.
I keep my tires at around 100 psi. It does make a harder ride, but I like the (fake feel of?) speed and feel it keeps me nimble. But God knows the streets of New York make me think I should get a bike with suspesion.
And I did ride my one speed recently with very low pressure and rode around like a fool with big grin because of how wonderful and different it felt (it's always good to ride a bike with a big shit-eating grin every now and then). But I did feel like peddling took more work.