Bag which doesn't interfere with my helmet - recommendation needed

I have a carradice Pendle, easy big enough for a full days kit. For lighter days I have a Carradice Zipped roll, i usually use this as my saddle bag for weekend rides as well, more than enough space for a half day. i can even squeeze in a waterproof if I pack it right,

I used to commute with a The North Face Surge laptop backpack which just about fitted my work clothes and lunch. It always worked well on the occasions that I wore a helmet.

I use a Deuter Cross Air for commuting too, though haven't had this issue with a Giro Monza helmet up top. My mate at work uses a 15L Osprey and actually, now you mention it, his backpack does sit lower down away from his neck than mine does!

Deuter Speed Lite?

There are 15 & 20L versions, my 15 seems to 'taper' towards the top unless it's stuffed full. Suspect you will have to visit some outdoor shops and try-before-you-buy.

Would you consider ditching the hat instead?

For the past three years, I've been cycling every day with an Aqua-Quest 'The Biker' dry-bag/backpack. It's 25L, square at the corners (so good for laptops), and 100% waterproof.

http://www.amazon.co.uk/Aqua-Quest-The-Biker-Waterproof-Backpack/dp/B004...

Only clicks on my helmet sometimes when I have it filled to the brim. Normally it doesn't go anywhere near -- I know what you mean though, it is annoying when it does. Might be worth mentioning I'm 6 ft tall (height must play a part in how well it stays away from the helmet).

Anyway, that's what I use and it works well enough for me.

What about a courier style cycle bag? Cycling with a rucksack is a no-no for me.

I have a Kreiga great for road bike, mountain bike and motor bike. Use it everyday. Not cheap but then what is, certainly not Rapha etc and there is far more utility in a good rucksack.

http://www.kriega.com/r20/

I had exactly the same problem.

It was caused by the fact that I have a relatively short torso for a man.

I solved the problem by buying a Vaude cycling rucksack designed for women, which is shorter in height than the non-gender specific ones.

I can't remember what it's called and it doesn't have the name on the rucksack itself.

The key thing is to check the size (height dimensions) of the rucksack before you buy it.

Over Board bags are good I've had one for some time and never have had any wet gear as it is 100% water proof. And it doesn't interfere with my helmet. Its at a decent price too.

I've had this problem too - I ride with an Altura Zone 25 (sometimes). I find that loosening the shoulder straps a touch but still using the chest strap lets it sit an inch or two lower and it doesn't foul my helmet. YMMV though, depends very much on position.

Alpkit Gourdon 20
https://www.alpkit.com/products/gourdon-20
Waterproof, tough, cheap, comes in different colours
Only downside is a lack of an internal key pocket but some sticky backed velcro and a cheap pencil case can solve that
I've had one for years for cycling with and its ace

Ditto above re Osprey - only I've got a Viper 9 litre bag - no issues re bag/helmet interference

I've got an Osprey Momentum that I've had no problems with, but I think this is going to be a very personal thing- you might spend a lot more time a lot lower than me. You could look at Wingnut if you want something that sits really low- I've no personal experience of their stuff though.
Maybe a seatpost-mounted rack if you're not going to be carrying too much stuff?

Put the bag on the bike not on your back. Cycling in a rucksack is like carrying a wheelbarrow full of bricks.

Or lose the plastic hat.