I just did the first front brake pad swap on my SS bike at 2100km (1304mi).
Here are the old pads next to the next pads ... as you can see the old pads are totally worn out:
comparison of old and new pads (top view)
comparison of old and new pads (45° view)
comparison of old and new pads (braking surface)
old pad surface after front duty for 8 months in english rain:
threw on some Jagwires Basic Pad (for £1.99)
braking surface ...
FINALLY, the real question ... how do I know when the rim is worn through ... it does have a groove and i can feel that it's less than the rear groove. it is when it's worn smooth or will wear indicators appear? just curious ... seems like I'll be lucky to get 5000km of out of the rim as I live at the bottom of a steep hill