Schwalbe big apple
The "apple" tire concept is one decade old, but with constantly increasing performance of the newest materials, large tires have become more and more fashionable due to the weight gain and increased resistance.
Schwalbe Big Apple is, according to many, the most accomplished product in this familly, and is collapsing under an avalanche of slogans and titles. "Best tire of the year"... "Perfect commuting tire"...
A mate who was using them on a folding bike and who was praising them focused my attention. I was riding so far my commuting bike with outdated MTB tires whose teeth had been long ago erased by erosion, and constantly subject to puncture flats. The Schwalbe were a bit costy and not very much in accordance to my philosophy that the commuting bike should be everything cheapest possible. But well, due also partly to pains in the back, I allowed myself this whim. I don't regret.
The two 26' tires (21mm width) I bought, at first sight, reminded me the shape of the Geax tires I had bought almost simultaneously for the other, supposing they would be completely naked, with all teeth been removed.
But, having a closer look, they are not exactly round, unlike their name "Apple" suggests. The section, when pumped optimally, is rather like an egg with the sharp end touching the ground. This way, the deepest they are pressed by the irregularities of the terrain, the most resistance they offer. Riding on them feels both really smooth, and precise like on a road bike when the terrain is perfectly flat. You just need to adapt the pressure to what you need.
All nowadays Big Apple are indeed the "Big Apple Plus", which means they contain also a kevlar membrane that prevents from most punctures. After two years of commuting with them, I had a flat only once, and only by pinch, due to riding under-pressurized. The kind of terrain on which they are most appreciated are on cobbles, which are found abundantly in my city.
Despite they don't own sculptures (or almost), reducing the Schwalbe Big Apple to a city tire is a bit reductive. They are perfect for mountain-biking, as long as most of your route goes straight, for example through flat forests, along rivers, etc etc. They perform particularly well when the soil is sandy, as instead of "digging" by projecting sand particles backwards, they compress it on all their width. The "flotation" feels unusually good and the gain of speed and ease is not neglectable. The Big Apple made me realize that most people who ride off road with deeply notched tires, when terrain does not own "mountainous features", are totally wrong...
I've used the Big Apple on almost all of my bikes: the old commuting one, the suspended one (perfect luxury for commuting in ramshackle city !), and they are now on the Blue Spec which has become a sort of road bike for winter trainings.