Hi All!
As the topic subject line says, Trek has just issued one of the largest bicycle recalls ever, at ~1 million units in the US and Canada. Interestingly, the nature of this recall is expected to have a ripple effect throughout the industry, prompting other makers to do similar recalls.
http://www.cpsc.gov/en/Recalls/2015/Trek-Recalls-Bicycles-Equipped-with-Front-Disc-Brakes-to-Replace-Quick-Release-Lever/http://s7d4.scene7.com/is/image/TrekBicycle/2015_QR_Recall_Releasehttp://www.trekbikes.com/us/en/support/safety_and_recalls/The recall was prompted by a loss of front wheel-fork retention, resulting in paralysis for one very unfortunate rider and injury to a couple more. The crux of the issue -- and the reason why it is expected to be so far-ranging -- is the quick-releases in question can open more than 180°. If riders leave the q/r in the open(!) position and ride, the lever can catch in the front disc while riding, resulting in accident and injury. This possibility is illustrated clearly in a graphic at this link:
http://www.bicycleretailer.com/recalls/2015/04/21/trek-issues-recall-qr-disc-brake-bikesApparently, this kind of q/r has been used on other brands of bikes equipped with front discs. The "fix" seems to be replacement with a quick-release that opens 180° or less and consumer education on its proper use.
For those wondering how a bicycle can be ridden with a fully loose q/r, the answer lies in another attempt to make these things foolproof: The q/r with spring-loaded washers. The washers will retain the wheel in matching dropouts even if the lever is loose. However, it is this loose lever that can rotate into the brake disc if it is the type of q/r where the lever rotates more than 180°.
Even on q/r without washers, wheel retention depends upon properly securing the lever. The lever can strike a protrusion like the fork blade or the disc mounting boss and fail to close over-center. Also, I have lost count of the number of people I've seen attaching their front wheel using the q/r lever like a thumbscrew, and that is simply improper. Unless the mechanism is adjusted so the lever can be fully thrown over-center for full clamping, the wheel will not be properly retained in the frame. A common rule of thumb often cited is to tighten the adjusting nut so it is contacting the dropout face with the lever at 90° to the other dropout face (pointing directly to the side) and *then* throw the lever over-center and closed. Another rule of thumb is to close the lever with enough force to emboss one's palm. Unfortunately, both methods can require more hand pressure than many can accomplish, and not all cams are equal in the leverage they apply to the dropouts. Internal cams have greater clamping forces and better wheel retention in general than external cams, which offer greater travel at the cost of reduced leverage.
Beyond the wide-opening q/r design in question, the core problem seems to be one of consumer education. Years ago, Bridgestone's marketing director Grant Petersen (later, founder of Rivendell) had custom nickel-plated "quick-release hub demonstrators" (miniature "forks" made from seatstay tubing equipped with brazed dropouts) made and distributed to dealers in an attempt to better educate consumers on proper q/r use. It might have helped, but who knows? I have two of these demonstrator stands from back in the day. Lovely things, maybe it is time to make and distribute a few more, with mandatory instruction for every new bike sold by a brick-and-mortar shop.
Trek have issued two YouTube videos showing proper use of two types of q/r, perhaps a useful review for those unfamiliar with its proper use:
Without washers:
https://www.youtube.com/watch?v=p0m2Jdfl8ToWith washers:
https://www.youtube.com/watch?v=YTLgcEViRo0Best,
Dan.
