There is often a right way and a wrong way to do things. In cycling (as in so much of life), it's not always obvious what the reasons for the right way are. In fact, I'm not sure it's even appropriate to ask. Why. (Isn't it enough, for instance, to know that Merckx did it that way?) But it is appropriate to ask what. And so here's your tip of the day:
Can you tell me which pictures below depict properly positioned skewers?
What do you think? Do you have it?
If not, I've created a handy graphic to help you.
I hope you had it right.
Now, usually it's not for us to ask why in such matters, but in this case I'll explain.
Safety. If your skewer is in the position depicted in the upper right-hand picture, I will assume that your wheel is not fastened securely, and that over the next bump or around the next sharp turn that your wheel will be departing your dropouts for good. Thus, a skewer lever pointed down means that a wheel is not securely attached. That's the only reason one should be pointed downward.
Doucheness. If your skewer is positioned like the one depicted in the upper left-hand picture, your bike looks ridiculous, and, by extension, it's going to be awfully hard for me to take you seriously as either a rider or, frankly, a human being. So while you're droning on about your latest epic ride, if your front skewer lever is pointed the direction we're traveling, all I'm thinking about is how I can get you away from your bike for a minute so that I can quietly and discretely correct this sin against theology and geometry. For the bike's sake, if not necessarily yours. Don't be a douche. Take care where your lever points.
Ok, so at this point you may be asking what rules actually govern proper skewer lever placement. I'll tell you.
(1) Skewer levers are ALWAYS secured on the non-drive side of the bicycle. For balance. Aesthetic balance, if not actual balance. Of mass. There are no exceptions, no excuses.
(2) In the case of an internal cam-type skewer, such as old-school Campy, most Shimano skewers, and the ones depicted above, the front wheel skewer lever should align as close to parallel to the fork blade as possible. But it may also dip down, clockwise, to the 3 o'clock position, but no further. Basically anywhere between parallel to the fork blade and 3 o'clock is fine, but at either extreme is best. With a suspension mountain bike fork, no position other than parallel to the fork blade is acceptable.
(3) When your wheel manufacturer has been discourteous enough to provide you with the other kind of skewer, an external cam-type, I would first recommend making every effort to get a new skewer (incidentally, the Angry Asian agrees), but if that's not possible, then the best position for the front wheel skewer is straight up, 12 o'clock, or any position between 12 and 3 o'clock, with preference again to the extremes or, in the best case scenario, and if your dropout placement allows it, parallel to your fork blade (this is always the case with suspension mountain bike forks).
(4) Internal cam-operated rear wheel skewer levers should be positioned parallel to the chain stay. They may also rest between the chain and seat stays or, if you must, at 3 o'clock.
(5) If your rear wheel has the other kind of skewer, it should be positioned between the stays. Or at 3 o'clock. (If you're feeling iconoclastic, 12 o'clock is acceptable, but discouraged.)
Follow these simple rules to keep your wheel skewer levers in compliance and may you enjoy many miles of safe, smug, stylish, self-satisfied joy upon your trusty steed.