Granted, all the brake adjusters I've seen so far are meant to be used for fine adjustment when you're NOT on the bike riding it.
Come to think of it, all Shimano groups have adjusters on the cable entrance of the brake callipers, don't they?
While the front brake and its barrel is within reach, the one at the rear is rather tricky to find whilst pedaling....
Still, assuming there's a cable guide lug running along the top tube of the bike, the barrel for the rear brake could easily be moved to the front just the same...
Voila, total weight preserved and the brake can now be adjusted from the comfy chair.
Just tell the mechanic it's not where he expects it be anymore next time you bring the bike around for a tune up.
BTP makes some cable adjusters too.
Yep....
At 3.6g they seem light but then again I haven't got the foggiest what such an adjuster would weigh at all....
Ciao,