Originally Posted by
OrbeaSorbet
bottom bracket shell: 68 x 34mm (id) is for the frame. not sure if this is what you're looking for.
68x34mm is a standard 'english' threaded bottom bracket, this is the most common type currently avaliable, the BB30 crank won't fit, you need something like a HT2 (Shimano type) or GXP (SRAM type) bottom bracket, and crank to fit that.
Originally Posted by
OrbeaSorbet
I have an ORBEA TRIATHLON Aluminum Alloy 700c for the front tire.
Do you mean fork? if so, is the steerer tube the correct size to match the frame? is there enough steerer tube left?
Originally Posted by
OrbeaSorbet
do the shifters really need to match the derailers? what ones work best?
For the shifters, they need to match the rear deraileur, SRAM won't work with Shimano, which won't work with Campagnolo due to different cable pull lengths, with the front, you can do more mix and matching. You also need to match speed i.e. 10 speed shifters need a 10 speed compatible RD. For which is best, take your pick of which you like, each system has good and not so good features.