Even disregarding the lack of disc mounts, is a Surly really worth twice the price of an On-One?
A Pompetamine or a Kaffenback would be a good starting point given the budget. Of course, a Look CX85 is what's needed to get near 8kg, but that's about £2500 for the frameset. No horizontal dropouts on those, but since fixed hasn't been mentioned I assume a tensioner will look after that.
Even disregarding the lack of disc mounts, is a Surly really worth twice the price of an On-One?
A Pompetamine or a Kaffenback would be a good starting point given the budget. Of course, a Look CX85 is what's needed to get near 8kg, but that's about £2500 for the frameset. No horizontal dropouts on those, but since fixed hasn't been mentioned I assume a tensioner will look after that.