I don't find the Arkel Tailrider to be hard to put on and take off at all, but mine is an older model, and they may have changed the mechanism. It's not huge, agreed, but I love all the pockets and the velcro on back, the visibility factor, and the the fact that it has a built-in rain cover. It's just incredibly well-built. And it does expand to be quite a bit bigger than it appears, but is still not a big bag. Perfect for the layers of clothes you might peel off, though, snacks, wallet, that sort of thing. And we've brought quite a bit of smaller food items back in ours on errand rides.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow