I've been in the market for a tank bag and couldn't decide on the Alpinestars Tech Aero or the Cortech Super 2.0 18-L tank bag, so I picked up both to decide.
The Cortech is an 18-L bag. It's 12-L and then 18 when expanded. It's very durable and rigid. It feels really heavy duty. There are panels that fold down when expanded to help the bag hold its shape. There are 8 magnets, 4 on the bottom of the bag and 2 on each "flap". They feel pretty strong and when on the tank it feels really secure. It's a really nice looking bag, however, he thing I don't like is how tall it is when expanded. I think it looks a little ridiculous, though it doesn't interfere with my view of the tach/speedo. Because of the magnets/flaps the bag is lightning fast to put on and take off, just set it down and ride and grab the handle and pull it off to go.
So, the Alpinestars. I really like the way it looks. The black and red look great on my bike (black with a bunch of red accessories). It's magnetic but also has several straps. The magnets however don't feel very strong. There are only 4 of them on flaps at the corners, not sure if they would hold the bag on their own. The magnets are in a velcro pouch so you could replace them with bigger/strong magnets. It looks like the straps would have go to around or inside the fairings. The bag zips off of the base that would be strapped down and it is pretty quick and easy to take off and put back on. I didn't bother installing these straps as I don't think I'd like the way they'd look. Fortunately there is 1 strap up front that can go around the steering head quickly and easily and can release and remove even easier. This will definitely prevent the bag from going anywhere. The bag itself feels well made and has nice materials, but overall isn't as rigid as the Cortech. It doesn't want to hold its shape as well. Not sure if that's cause it was smashed in a box with the Cortech.
The Cortech bag is narrower and much taller when expanded. The A* bag is bigger all around, but I don't think it looks too big for the bike. The Cortech expands from 12 to 18L, and the Alpinestars from 20L to 30L. To test I put in a full size bath towel, shorts, shirt, socks and shoes. The Cortech definitely has to expand to hold all of this. I had the A* expanded, which only adds about 1.5" in height, but I think it would easily fit all of this stuff without being expanded, but also, because of the minimal height increase, there's no worry about leaving it expanded all the time. There wasn't much free space in the Cortech with all of this in there. I could probalby squeeze a few small items like deodorant and some travel size toiletries for the gym. There was noticeable more room int eh A* bag (obviously given the larger size), however, the A* doesn't seem like it's 12L bigger than the Cortech.
So you can't go wrong either way with these bags, however, I think I'm going to keep the Alpinestars and return the Cortech. I like the looks and the overall size of the A* better. I like the magnets/attachment of the Cortech better, but the single strap up front on the A* should be easy enough to deal with, and I'll look into getting better magnets. I also like that the A* bag has a bungee web on the outside where I could hold something else to the bag. If Cortech had a bigger wider bag that didn't have to get so tall it would be a tougher choice.
Thanks to Mike @ridersdiscount
for the great price on both, and for the ability to return the one I don't want. I'm NOT being compensated in any way for this review, I'm just doing this because I have access to both bags and hope it helps the community.
I took some pictures of both bags on the bike, along with my perspective from the riders position with my left hand on the handle bar (I'm 5'10"). I didn't have any gear on, but was right up against the bags, though there is a little bit of room to push either bag forward if you need more room. Let me know if you have any questions.