Hmmm. as long as you don't stomp on the saddle, I'm pretty sure the rails will take your weight just fine. But I'm surprised you're needing that much force. Unless there's corrosion or rust or something in between a short yank should loosen most wheels (well, most wheels you just lift out, it's just the chain and derailleur gizmos that add sideways drag). I know you said you've loosened the QR, but it sounds to me like it's keeping the wheel snug. Just check once more, that you're absolutely sure it's open and loose, the same way as on the front wheel. Loosen/open the brakes (you'll see the brake pads moving away from the rim to give it clearance). Let air out of the tire and squeeze the tire with your fingers (you should see that the rim and tire will then easily be able to pass the brake pads).
Have the chain on the smallest cog, and try pulling the derailleur back and forth with your hand (a bit greasy), see if you can actually pull the chain off the cog. The drag from the chain wrapped around the cog should be the only thing keeping the wheel a little "stuck". Give the wheel a little wiggle back and forth while you're doing this, and you should feel that it just sits loosely in the dropouts and can be lifted out once you maneuver the chain off the last cog.
The problem with removing rear wheels is sort of that are a lot of small sticking points that need a little wiggling almost at the same time, but there shouldn't be any real force involved.
Pardon the sermon
Last edited by lph; 03-05-2011 at 01:21 PM.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett