Just bought a Jamis Sputnik single speed and have taken it out for two rides of 20 plus miles. This is my first experience with a SS (not fixie). During the one climb on each outing I definitely noticed flex and I am pretty sure it came from the wheels.
No big deal, but I have been riding a couple road bike with Mavic Ksyrium SL wheels. These wheels are great for a little heavier rider and there is no noticeable flex on a climb.
Looking for suggestions for a wheel similar to the road bike wheels I am using, but built for the SS. My search has been Lackluster at best, so I am now turning to the guys with experience.