Hi guys-------- yes, I agree with PeteF........I currently operate an Oxy-Acetylene outfit and have done so continuously since I first qualified during the 1960's..... It's not so much the temperature achieved but more about the Quantity of heat required to do the job in hand..........Have a look at the short video within this link and you'll see what I mean---- All the examples are of thin, sheet metal whereas your typical bike frame will be much thicker AND of greater volume.......It's not only getting the combined workpiece up to temperature but maintaining that "Background" heat whilst you do the actual brazing that eats up the gas and those disposable canisters just don't have the capacity............
https://weldingsuperstore.co.uk/brand-oxyturbo.html ..... ...MiG welding might be better as only localised heat is produced but in either case this is not a job for the inexperienced.....If I were you I'd take it along to a professional Welder for peace-of-mind..