Ummm, not sure tbh. I don't think they ever listed this on their website either. At a guess maybe 1.8l? There's no rigidity to it so you can stuff quite a lot in, deffo enough for a day ride. I've had tools, tube, softshell and some snacks in it. I'll take more pictures later.
Pics: https://www.dropbox.com/sh/dobi8hs776xj26b/AADDrKQOP2_nSfNGSe8Y-ZSma?dl=0
Very beater saddle - free
Ergotec bars (these ones: https://www.planetx.co.uk/i/q/HBHUBOOM/humpert-ergotec-boomerang-handlebar) - used once, weird shape, SOLD
Campag Veloce calipers - bit long in tooth, need new pads, £5
Big Top saddle pack - 1.6l, light use, £20no longer for saleShort ITM Ribble tatty seatpost - free
Banjo Brothers frame bag - used once, have cut the straps down to make more usable as they were way too long, SOLD
Tektro drop levers - SOLD
Would rather not post. Pick up from London Fields E8 during the week or SE27 in the evenings and weekend.