Thumb position on the neck?

[Mr wiggl3s]

I've read that it goes both ways. I feel parallel is the best, but a very established bass friend of mine says clamp style is the way to go. What's the general consensus here? Any supported opinions?

[penguinbass]

hmm. I used to play with it behind the middle finger because that's what I heard, but then I realized that that's pretty unnatural. I try to get it where it would be naturally when my hand is not doing anything.

[GianGian]

Perpendicular usually, you can reach more notes. But if you are not moving too much you can play more relaxed in the "thumb facing headstock" position.

[Chris K]

A pity you missed 'electric guitar grip' (thumb over fretboard side). I see it quite often with guys who mostly play blues or funk stuff and care little about speed. So style may be a reason for a choice of thumb positioning.

For general playing as well as for beginning players, perpendicular is the way to go. If you call that unnatural (like penguinbass does), you are most probably keeping your left elbow pretty close to your body.
My preference: if the hand is about halfway the neck, I keep my lower arm in vertical position; elbow out and to the front as far as relaxed playing permits. The larger part of the movement of the hand is coming from my shoulder, not my elbow.

[Michael Campbel]

I liked HaVIC5's blog entry and video on this subject: http://adamneely.com/2010/07/17/that-pesky-left-hand/