I've found sudocream to be very effective, and was recommended to me by others who swear by it.
+ 1. Cheap and cheerful. Sudocrem is just fine.
buy good bibs/knicks that fit well ............. prevention is better than cure :)
I've learned my lesson, go commando!
It worked for Sharon Stone
having just ridden 2000km in 2.5 weeks, good knicks (layered with chamois cream - Aussie butt cream is what i use) , good saddle, correct seating position and some fellow riders used Pawpaw cream after riding (I didn't use it as my backside was in good shape but they swore by it for recovery and were doing 8000km in 11 weeks)
Can't say enough about correct seating position, get the pendulum out and be sure that your saddle and backside are at one with each other!
I think its a friction thing as this is the first prob I have had in over 5 years
Best treatment, is prevention. - easier to prevent sores - than to treat them once they are there.
They take a while to clear up. Specialy if you get them in the middle of a long ride. You get them one day - the next day, exactly the same spot, already chafed, trying to heal, gets more chafing
Plenty of comments above, how to prevent. "chamois cream" works for many people - ie spread it over yourself, before riding,
Cream! Lots of cream.
Make sure your saddle height is correct and you are not rolling from side to side as you pedal.