Largest pannier for real backpack insertion?

[RMSDivine]

Hi there, I've ben using for years an Ortlieb pannier with removable insertion to carry my laptop etc. Quite messy finding content which will inevitably stack.. I have started searching for viable solutions, and I have discarded convertible models.
I think the best combo would be purchasing a proper backpack and use a large pannier as a waterproof container.
At the moment I am using an old but very functional Samsonite backpack, however my Ortlieb pannier isn't enough wide to accomodate the backup, leaving about 15cm unused, mostly because it shrinks in the lower end.

Just wondering what are the largest available waterproof panniers for this purpose: real backpack insertion

 

[Stefan Mikes]

Ortlieb Vario pannier-backpack

I have used the 26 litre version of Vario since March 2023. This is the new version of Vario (the old version was available in 2020), which is converted between the roles by simply relocating a single flap.

Highly recommended.

I have started searching for viable solutions, and I have discarded convertible models.

I wonder why. Vario is a backpack and it is a pannier. Waterproof.

P.S. I could fit a small Samsonite backpack (that I use for the laptop for my business trips) into the Vario 26 l easily

 

[RMSDivine]

Because the Vario it is neither fowl nor fish

This is true usability:

 

[Stefan Mikes]

Shouldn't be a good Samsonite backpack at least water-resistant?

 

[BlackHand]

Have you considered 2 Wheel Gear? I see someone occasionally with their more basic convertible and he says he loves it. Setting aside the weird 'smart' feature the Alpha looks like it has what you need.

Alpha Pannier Backpack SMART (25 L)

The Alpha Pannier Backpack SMART integrates with the Joey T3 Smartbag Console (sold with or without) and Joey T3 Smartbag App. Charge your devices on the go, connect your bag to your phone via bluetooth, set anti-theft alarms, find your location, and much more. With a comfortable 25-litre...

twowheelgear.com

 

[Slaphappygamer]

I got a framed Osprey backpack and strapped it to the side of my rear rack. Like a pannier. I had to be careful that the shoulder straps wouldn’t get stuck in the spokes. Velcro (hook and loop) worked great for keeping straps tidy. I had the backpack opposite of the cassette for obvious reasons. This worked well, but I hated strapping and I strapping the backpack once I reached my destination. I finally said “F it, I’ll just wear the damned thing.” .

 

[6zfshdb]

I'm not sure what you have against a convertible pannier / backpack. This new 25L model from Arkel looks promising:

Bug - Pannier Backpack

This bag converts from a pannier to a backpack in seconds, perfect for city use. The well-designed biking backpack offers many different features like 2 side pockets, a helmet holder flap, a laptop compartment, etc. Also, its backpack straps make it very practical for an urban lifestyle!

arkel.ca

Comes in several colors, uses rugged YKK zippers, has a weatherproof laptop pouch, and will fit almost any frame rail.

I've been using their 18L model for many years and have had no issues.