So I can’t carry a backpack any more – the pain is too much since the back operation.

I can transfer the liquids to a bottle on the frame and tools to an under-saddle pack.

Can anybody recommend a good hip pack around 8 litres?

I was going to suggest the Ortlieb but the largest is only 6 Litres.

Would a hip pack still place loads on your spine (all be it indirectly)?

What about a frame bag (Alpkit Possum-ish)? Get all the stuff off you and onto the bike.

I’m the same, find the backpack is just too painful now after breaking mine. What’s in the 8 litres?
I’ve switched as much as I can to off me, specialised xc kit puts a tube, levers, co2 etc in a box off a bottle cage, a multi tool off another and a chain tool and links in the top cap. Toestraps or saddlebag then for anything extra I need or a second tube and co2 cart, and I hang a small frame bag under the top tube by the head tube.

Jersey pockets for everything else, sees me sorted for every ride, very rare i need all the frame bags.

To answer the actual op, Osprey do one but 6l. The only 8l I know of is trespass waikaka but it looks like it would be a bit of a weight full. Only a fiver though at the moment so worth a punt?

My long time go to is the Mountainsmith Tour pack 9L : Mountainsmith Tour Pack

There is also a strap option if you want carry a lot of weight.
Strapettes

Decathlon do a 10l one that I use for local rides. My only grumble would be that it has a bottle pouch on each side so unless you use two bottles it can pull down on that side which becomes uncomfortable after a couple of hours.

I can only get a 500ml bottle on my T129 and as it’s getting warmer now I want more fluids when going out.

The straps cinch up making it quite compact if needed and it feels quite stable in use.

HERE

Currently using the Talon 6

qwerty I have fractured vertebrae between my shoulder blades (T5,6 & 7) with a metal brace in there as well, so a bit of weight around the waist will not affect itm

Thanks for the advice all, I’ll give the suggestions a good look.

just got a montane bat pack 6. £30 at their factory shop in Ashington. very happy with it.

You’ll be surprised how much crap you can fit in a Talon 6. Well worth a look.