Valve length

[quixoticgeek]

I've got a pair of DP18 rims on my wheel set, I need some new inner tubes. I'm trying to work out what valve length to get tho. The rims are 30mm deep. Is a 40mm valve going to be a bit too short? Is there any disadvantage of having a valve that's too long?

J

[Feanor]

Mrs F's bike has 30mm deep rims ( as measured externally ), and 42mm valves are useable, but only just.
It definitely looks quite 'stubby'.

Depending on your model of pump head, it might struggle to get enough of a grip.
It's fine with all my pumps.

I've just purchased a few longer ( 60mm, but I'd have been happy with 50mm ) tubes to use on these wheels.

So I'd say that 42 is OK at a pinch if it's all you have to hand, but I'd not buy them that size for that wheel.

Over long valves are perfectly fine on shallow section rims, they just look a bit weird.
I've run 80mm tubes on occasion on my normal-section rims.

[zigzag]

42mm valve is just right, no point in having a valve that's too long (and it looks daft)

edit: almost a cross-post

[frankly frankie]

I always carry a valve extender in case of need
eg:
http://www.wiggle.co.uk/lifeline-valve-extensions-for-non-removable-vc-2pk-40mm?sku=5360597738&source=igodigital