Originally Posted by Twig
Maybe you could ask them for some comparison numbers of cryo'd gear strength vs outta the box gear strength. Then you could decide if it's worth your money.
You need to study the changes of austenite to martensite in steels to understand the cryogenic process. It has nothing to do with congealing of the metal itself as all that happens as soon as the steel cools enough to solidify.
There is a contention that the heat treat process is incomplete at ambient room temperature and needs to continue futher down the temperature spectrum until about -190 or so. Ideally the -450 or so temp that indicates absolute zero or the point at which no molecular movement is able to occur would be best but that's not economically feasible or more likely even achieveable.
In a nutshell, studies have shown that the change from austenite to martensite still continues at room temperature to some degree and to complete it the heat treating needs to be continued cryogenically with liguid nitrogen to finish.
There is some debate as to it's merits, but studies do show an increase in overall strength, hardness to a small degree, and wear resistance.
Do a austensite to martensite search on google and do some reading. Most of it is pretty technical in nature and too far advanced for my limited education to deal with and regurgitate accurately.