I had a Saracen 2.six for a year with standard cranks and bb and there was no problem with the chain rubbing on the frame. But one of the first problems I had with my Saracen was when I pedalled hard the frame flexed making the brake touch the rim. I sorted this by bodging an echo 4 bolt booster on the brake, also my Saracen cracked on the right hand side right by the bb so keep your eye out for that.