The Tailrider is excellent unless:
a) It's too long for your rack
b) It's the time of year when you need to start and/or finish the ride in full winter kit, and remove most of it after an hour or two
Apart from that, big thumbs-up for being sturdy and having pockets, and at least looking vaguely aerodynamic. Points deducted for shower-cap waterproofing (not that it doesn't work, but I don't think to dig it out until everything's unambiguously soaked), but there aren't many options that are truly waterproof without being a single compartment.
The single compartment isn't so bad if it opens up like a carrdice saddlebag
Wish list
- narrow enough / short enough for Tortec Ultralight ( 11cm x 35.5cm ) and similar
- attaches using velco straps ( or anything else that is just as good )
- water proof without using a cover
- two side pocket with a water proof zip + storm flap + tags to make zip operation easy
- loop for light
- internal compartment at least 15L with some side pocket / organiser (not sure if this actually makes sense with the rack size)
- weight 500g ONO
Current things
Lomo - too heavy, weird attachment, one side pocket that isn't waterproof enough, no loop. Cheap though!
Tailfin - too expensive, attachment could be better,
side pocket is open to the elements Ortlieb - have 6 different types of bag. Mostly they are too small. The "Rack Pack" is a nice size (24L) but isn't designed for direct rack mounting. None have waterproof side pockets
Carradice - "CarraDura Rackbag" isn't really waterproof and is too heavy but otherwise ok. "Super C Rackbag" too heavy, too small, only one pocket, waterproofing is good
Vaude - have a series called "Silkroad" none of them look actually waterproof (they are described as "water resistant") and all are too small
Alpkit - weirdly don't have a racktop bag of any sort as far as I can see