I have an
Altura bag, and there are a few features that I like about it, and a few features I would like to change:
Detachable map sleeve (with velcro and two poppers to hold it on) made of a rubbery clear plastic that doesn't crack as it ages. When I don't use it, I leave it behind. This feature could be improved by getting the other end of the map case fastened down to prevent it from blowing over the front of the bag in windy weather. Perhaps another bit of velcro on the underside of the map case, about 3/4 the way down towards the open end? I get fed up with tossing it back up onto the lid! The size of the case needs to be looked at hard. My current one is fine, but I have had one that was too small - the designer did not consider the length of the map, nor the resulting bulk when it was folded backwards to show the route.
Detachable strap: I can go into town and carry it over my shoulder, when I leave the bike locked up. This could be improved upon: use non-slip webbing! The strap frequently lengthens itself when it is on the bicycle. Too, I wonder if the attachments could be made smaller or changed, as they are quite bulky. I had been going to suggest a narrow zip pocket that follows the width of the bag, in which to tuck the strap out the way instead of having attachments for detaching the strap. This might be too fiddly.
Some support for the bag, if not solid, particularly around the the top, either as a frame or board. I had a bag that only had the back supported. The bag tended to flop down when anything heavy was put inside. A frame around the top might work along with a back board. My current bag is like a plastic box covered in material, but is a bit on the heavy side, and hurts my hips when it bangs into me as I walk along. If it were lighter I would feel much happier with it.
Velcro for the lid: yes and no. Quick to open, but hell keep closed if the bag is a bit full - it tends to flop open, particularly over bumps. Two or 3 poppers on longer tabs would help to keep it shut when it is full.
Outer pockets: very useful for putting last minute small things into, but may get in the way of gear shifters if at the side. I may be in the minority on this issue, as I have drop handlebars, which may be narrower than others.
My bag has a detachable front outer pocket, that is held on with velcro and quick release buckle, and can be used like a bum bag when the strap is removed from the handlbebar bag and is attached to the outer pocket. I seldom use it, and the quick release is bulky, getting in the way of the shifters. I think I would prefer a single outer front pocket, that remains permanently on. An attachment for a reflector or better yet, a light. Handlebars are too crowded these days for all these things, and a light on the fork crown sometimes gets hidden by a drooping handlebar bag!
Inner pocket(s): An inner pocket is a good idea, particularly for things that get lost easily in a bag, such as keys and rail tickets.
Size: Something that is big enough for wallet, hat, suncream, book, mittens. Just trying to think what else I carry in it when I am touring and dislike having to stop to hunt for in panniers.... Small camera and sandwiches! Ah yes! Very important... flattened loo roll.
Colour: black: does not show the dirt and goes with most bicycle colours.
Waterproofing: it depends on how expensive the material is. A cover over the bag may hinder access to the inside of the bag when it rains, but does have the advantage in that it covers the whole bag and reduces water ingress between any seams/lid in heavy, prolonged rain. If the cover is made with a waterproof material, it should last as long as the rest of the bag. PVC-lined trousers loose their effectiveness as the lining perishes/wears. If a cover is made for the bag, I would suggest that the elastic is enclosed in a seam, rather than sewn on directlly. It would be good to be able to replace the elastic as and when it perishes. Perhaps use an elastic draw cord such as those found on waterproof jackets?
Attachment: I say aye to the Rixen Kaul KlickFix.