Safety Tip for March 2008by Tom Armstrong
Most of us have learned the ABC Quick Check. It is a pre-ride inspection process that helps us have safer bicycles by giving us a chance to catch small problems before they become large problems far from home. Iíll be covering the ABC Quick Check in more detail in upcoming columns.
For now, however, I am going to share an observation with you, and offer some suggestions.
Since I spent a lot of time working on bikes, I spend a lot of time looking at folksí bikes. Since I am perhaps a bit overconscious on safety, my eyes are drawn to the quick release levers, and find that many have misconceptions on how these gadgets work.
The quick release lever operates a cam. A cam is shaped with a lobe. The importance of this is that when the lever is properly closed, the lever has the cam turned beyond the lobeís high point, meaning it will take more force to open it than close it further. If it is not closed far enough, it will take less force to open it than close it. Read that last sentence againóitís one of the two main points of this essay. If it takes less force to open the quick release than to close it further, the quick release lever can work its way open on its own.
For my other main point, and itís related to the first, I want to address where the lever points when you are riding your bike. For old-style levers, those that have an ďLĒ shape to them, itís generally best that the lever point up the fork blade, although it is perfectly acceptable that the lever point straight back when the bike is being ridden. The point is that it should not touch the fork blade at all; if it is touching the fork blade it may not be completely closed. The newer alloy levers, that lack the ďLĒ shape, are often best pointed straight back toward the rear axle, again mindful that no part of the lever touches the fork. This does two things for you: It allows the lever to close completely, and allows you to get a grip on it when you need to use the lever.
For quick release levers at the rear axle, the same basic rules apply. The biggest exception is that most folks donít like having their levers pointing either straight back or forward under the chainstay, lest the lever be accidentally opened by another cyclistís tire in a pace line or a stick thrown from the roadway. Many folks aim the lever between the chainstays, which is my general preference on conventional bicycles. There are bikes with dropouts that donít allow this, as the lever would be touching the dropout or a chainstay, preventing full closure.
In closing, Iíll remind you that you donít need to be Magilla Gorilla to close a quick release tight enough to keep your wheel in place. A very good general rule is that if you feel resistance on the lever when it is pointed straight away from the bike, it will be tight enough to do the job well. You should see an imprint of the lever in your hand for a couple seconds after you close the lever.
As always, Sheldon Brownís web site has some very good images and more detailed discussion.
http://sheldonbrown.com/skewers.html will get you there.
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web posted: 17 Jan 2009
last updated: 17 Jan 2009