1
2
I would like to be the first to really, really hate geared hubs here.
It's the power losses. Being even 5psi low bothers me enough, the drop in power transfer efficiency from 99% to 85-ish% makes me go ballistic. Enough so that it is worth it to me to have to eat a chain/cogset/chainring set every 500 miles or so as opposed to not having to.
The absence of a derailleur is not going to reduce the wear on the chain and cog. 
Yeah, but shift quality doesn't degrade, and the lack of a spring loaded chain tensioner means that the chain won't jump when you stand to hammer up a hill, resulting in intimate contact between one's privates and the clampy doodads on the threadless stem.
I don't think the efficiency loss will bother me.
I've been sidetracked by a FAL build though. So I probably won't get to this until winter is in full swing.
Also to the guy who was asking about a mountain bike build:
Look into the 8 speed hub, as it's supposed to be the most rugged, although I don't think Shimano endorses the hub for hard-duty use.
noisycricket wrote:Yeah, but shift quality doesn't degrade, and the lack of a spring loaded chain tensioner means that the chain won't jump when you stand to hammer up a hill, resulting in intimate contact between one's privates and the clampy doodads on the threadless stem.
Shift quality will degrade with both systems if they are not maintained properly.
And, I feel the need to point out that the spring tension that the rear derailleur provides is just to keep the chain from slapping about, it has nothing to do with overcoming any brute force that you are applying to the crank. A badly adjusted rear derailleur may not line up correctly with the cog, therefore added force applied to the chain may result in the chain wanting to drop down to the smaller cog, but again, nothing to do with the spring tension itself. A very worn chain and cog will also experience chain jump, where the chain rides up and over the tooth, and can also throw your privates against a hard place, regardless of the presence of a rear derailleur. An improperly positioned wheel on a singlespeed can contribute to chain jump too. By not pulling the wheel back far enough in the frame you will experience a lack of chain tension that will allow the chain to jump over the tooth under load.
I'm not really sure what you mean when you say you hate geared hubs, but I can understand having a passion for singlespeeds if that's your thing. There is a reason why there are so many different kinds of bikes, there's so many different kinds of us!
