MightyMouse, I completely agree with you, and the response I got from the Triumph manager just confirms my view: "We know about the problem (read: our engineers messed up on this one...), but we couldn't care less because it doesn't bother you *that* much—plus, it keeps you coming back to the dealerships where we hope to offload more gear on you." Basically, they're taking us for fools! It's a shame, because I wanted to buy a Bonneville for my wife, but I think they can keep it... To answer Nashvegas regarding brake fluid: since the system was bled, mine has been running on Motul 5.1—currently the top-tier product from this world-renowned brand—and it made no difference; after 2,000 km, the brake pedal travel increased again...
My next step is to insulate the rear brake line that runs *through* the lower engine casing (did an engineer actually approve this design?) and—despite what I said below—try replacing the 5.1 fluid with RBF 700 (with an annual flush), because I’d rather work on the bike than end up in the hospital!
I wouldn't recommend using true racing fluid like RBF 700, as it's even more hygroscopic than the 5.1 (it requires changing after every race... or at the very least once a year for a road bike).
NB: I think the site administrator could move these posts to "rear brake problems"...