Valve Stems - how long?

[threebikes]

I have 32mm carbon rims and a few tubes with 42 mm stems.
Should I buy some tubes with 52mm valve stems or just
use the 42's ?

[LC]

Depends on your pump but I would get stems at least 48mm long.

[threebikes]

Thanks LC

[martinot]

It probably adds a bit to the imbalance of the wheel (although I have not noticed even @ super high rpm) but I like my stems to be exposed by at least 2 cm and preferably even 3 cm. Anything less than that is a pain during first stages of pressurizing (and I ride exclusively on latex tubes so pressuring is a daily routine). I'd go with 52 or even 60mm length.

[sixteenornumber]

I would use whatever fits. if the pump works on it then it's all good. That being said, I wouldn't use 80mm steams.