UKH

This obviously depends on the even and the kit lit required. 

But what packs / pack sizes do you use for ultra marathons?

Cheers

GG

Salomon Sense Pro 10, very good for summer events and training runs. Super light, and breathable (no stupid waterproof back panel) holds loads of stuff and easy to get to things and it’s red so makes me run faster.

might go back to a 12L for winter events but I don’t do many of those. 

Salomon S/LAB Sense Ultra 8. Despite its light weight it’s lasted 4 years. Amazing bit of kit that’ll fit climbers’ physiques unlike some of the other brands that only have 2 or 3 sizes.

I fell like a 10 l is just a tad small for me, for winter runs. (I like winter runs, maybe I like pain). I have a dechatlon 10 l trail running pack which is fantastic but its not red, maybe that's why I was slow in my last race. Might get the 15 l version too. 

do you manage to fit everything in 8 l for an ultra?

Yes, easily. You can fit a winter hard shell, insulated layer and waterproof trousers in, as well as mitts, survival bag, first aid kit, food and 1L of water. 

Montane Gecko VP 12+

Has the best working soft flasks and soft flask holders of any vest I've used

https://montane.com/products/montane-gecko-vp-12

If you aren't looking to pay the extortionate Salmon prices, this local brand produce some good vest packs. Personally use the 10L and it has every kind of attachment you would ever need, plus enough space for the mandatory kit. 

https://harrierrunfree.co.uk/

I really like the Ultimate Direction packs.

Got an 8L Race Vest

The Mountain Vest at 14L

and a Fastpack 20L

I tried the 10l harrier and couldn't get on with it. Getting bottles in and out was very hard and it didn't sit square on my back

With the larger ones do you get a particularly sweaty back? I never imagined running a long way with such a large bag, til I saw these. 

That's odd as I don't have an issue with my 250ml flasks. I have three vests and its the easiest to get them in and out! I know the vest comes in different size options so perhaps the size you ordered does not work very well...

Another vote for Salomon. Some say they're expensive but it's a quality, specialised bit of equipment that you don't want falling on you or chafing in what can be a hard enough challenge as it is. I used to use UD for years but swapped brands when it was time to replace my old AK3.0 

I use the new Salomon ADV Skin 12 because in an ultra I'd rather have space to spare and you can cinch in the pack so stuff stays secure. The pole carrying system although a little confusing at first is very flexible. 

The latest version is very stretchy and great for easily stuffing things in and out while on the move. I wore it for 42 hours straight during the UTMB and had no issues with comfort whatsoever. 

I'm thinking of buying a smaller one for shorter races. 

To buck the trend, a Black Diamond Distance 8. Narrow rear profile for kit which I'm unlikely to get out anyway. Enough pockets and stuff up front for water and food. Have used UD and Salomon in the past (still have a Fastpack 15 and a 3L Salomon vest) but the BD vest has been thrutched and chimneyed up some awful scrambles and looks pretty damn close to how it was when new.

Blimey, my mitts alone fill my Salomon ADV Skin 12.  Admittedly they are big mitts.

Salomon Advanced Skin 12 (old style). I love it, but I, like others have found the zips the vulnerable area and I am careful to keep these lubricated and clean. 5 years now, although looking a bit transparent in places unfortunately.

When there is a requirement for more kit (due to weather or in less supported events) I have a long tubular-shaped stuff sac which I use in the back mesh pocket for things I need to carry, but won't use very much. 

The new design have minimised the zips and mostly use stuff pockets. 

To be fair to any.manufacturer, they don't make their own zips and they're one of the most common failure points on bags and clothing, especially when they get gunked with sweat.