Thank you all for your input. To give you more context, I visited this bike shop about 3 years ago to get a new rear wheel for my 1994 Trek 800. Without my permission, they installed a solid axle wheel instead of quick release one that came with my bike. Although the new wheel has performed well, recently, I have needed to remove the wheel, and I greatly miss the convenience of the quick release system. So I posted a negative Google review for that bike shop, and part of the owner's reply to my review was the warning of the safety issues of using quick release on a rear free wheel.