I have worked on another option, taking comments on board.
I have focussed on a back print because this is visible when climbing, therefore in the majority of climbing photographs. I have tried to find an iconic position so that even without reading the text you might recoginse the tee from a distance because of the postion of the back graphic.
It is also cool for climbers because by seperating the shoulder blades it makes the back appear broader, and the wearer harder.
I think that using the text UKB is a cool idea because it is the simplest expression of UKbouldering. It is also a bit intriguing so that somebody might see UKB and think "I wonder what that is". This would make them more interested in the UKBOULDERING.com text on the front, if and when they see it.
The text is now tonal, so it would be a darker version of the tee colour in order that it is not SO standout.
Below is photo of me with an approximate version of the graphic. The colours are not correct, but I think the size an postion are about right, maybe it could be a bit smaller.