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Tester will know.

Yes, after you've added the adaptor to fit normal bars the Vision lever ends up heavier than the SRAM TT900. Also, the Vision ones are horrible to use.

Im probably making a big mistake here, but I disagree mdcc. For the same leg extension, a longer crank arm will mean your saddle will have to sit lower. When the crank is at 6oclock, the distance between the spindle and top of saddle should be the same for all crank lengths. So 180mm crank would need 10 mm lower saddle than 170mm. This is what scherrit at bike whisperer confirmed to me too.

Yes, if you keep the same leg extension, but that's not what limits most people's position, it's hip angle closure. If you use 180mm cranks and lower your saddle 10mm to keep the same leg extension, your foot will rise 20mm closer to the saddle at top dead centre, which has the same hip closing effect as lowering your saddle 20mm without changing cranks. Assuming that lowering the saddle improves CdA, surely you'd be better keeping the 170s and dropping 20mm rather than switching to 180s and only being able to drop 10mm?