Surely the additional energy required for each click needs to come from somewhere?
it takes a miniscule amount of energy to generate sound compared to the amount it does to generate heat. If you wrapped cotton wool round a clicky freehub (to absorb the clicking noise) it'd not get measurably warmer.
Basically, the clicking will use energy, but other efficiencies\inefficiencies of the freehub probably make much more difference
They DO create extra drag, but only when you're not pedalling.
Hope freehubs in particular can induce a noticable dip in the top chain run when freewheeling.
the loudness of the click has as much to do with whether the freehub body resonates the sound of the pawl hitting it as it does with how much spring force (and therefore increased drag) is acting on the pawls.
so no, not necessarily.
Because the click is there regardless of the freehub type/brand. A clicky one just indicates that the sound isn't being deadened by grease/seals/bearings/metal. So a clicky one my actualy have less drag as it has less sealing/grease in it.
EG my hope XC hub is really clicky if you put a drop of chain oil in the freehub, but almost silent if you add grease, freehub works just as well either way, mildly more drag when stuffed with grease.
the click is the pawl dropping back into the slot, not it being pushed up
I suppose it might imply that the spring is stronger but I doubt it's a significant concern and probably as likely to be the slot/pawl design anyway
<wanders off to fit softer springs to WC race bike hub>
Sorry to jump in on this but what causes the sound to diminish? I got a pair of Fulcrum Red Metals with a lovely note and they have either gotten noticeable quieter or I am getting used to them!
I find my hubs bet louder with age as the grease gets moved around away from the ratchet pawl interface areas (particularly hope).
The drag issue is pretty negligible though, when compared to the amount of bearings and seals that a decent hub has. Even then, the amount of drag caused by that is negligible in comparison to the rolling resistance caused by tyres and the tyre tube interface which has much more leverage and therefore causes more torque per N of friction.
and the tyre tube interface which has much more leverage
You mean inner tubes create additonal drag compared with tubeless?
Yup, the tube and tyre rub against each other as they are deformed by whatever it is that your rolling over, dissipating energy. This effect gets worse with lower tyre pressures as the two bits of rubber stick to each other less and rub more.
As the friction occurs at the edge of the tyre, you have in effect a lever ~35cm long in comparison to a lever ~2cm long due to your hub friction. As far as I understand, this is why you can have lower rolling resistance using tubeless compared with tubed, even with lower tyre pressures.