The rear rim you have is deffinatly an onza hog, but one of the ones that was made with round holes and not the hog shaped ones, they are exactly the same as koxx/trialtech rims etc except for the fact that they have eyelets, the eyelets do add a little weight, usualy around 30-50g for one rim. If you were to ditch the maxxis tyres front and rear and the heavy duty tubes and changed to say a rubber queen rear with a std tube and a try-all conti mountain king front with a std tube you could loose almost 1kg from the bike!!! (thats assuming the front tyre is also a dual ply, if it is a single you may loose around 600g) The mountain king front tyre will not be as grippy as a try-all tyre, i have ridden a fair few different bikes with these tyres fitted and i have always found my try-all tyre to grip alot better (and its pretty much bald!!) The mountain king would probably be ok for street. I am not sure what sort of weights those DDG hubs are, the front one could deffinatly be changed for something lighter, if you are on a budget the echo TR front disc hub is very good hub! Hope that helps a little, if i think of anything else i will post it up. Adam