Originally Posted by
Torrilin
An internally geared hub is slightly less efficient than a derailler system, on the order of 1-3%. A filthy chain on a derailler based bike can add far more inefficiency. The main advantages of an internally geared hub are shifting at stops (which is a godsend if you ever have an emergency stop with 40lbs of groceries), and the ease of protecting the chain from the elements (which is primarily of interest in a wet or snowy climate). The latter advantage probably isn't in AZ.
If you're not looking to use the bike as a car and still want the clean look, I suspect you might be better off with a singlespeed or fixed gear bike, geared so you can work on your spin. That eliminates the inefficiency of a shifting system, lightens up the bike, and should net you helpful gains for racing. There are a fair number of road focused bikes along those lines that should work well for you.
If you're the sort of rider who really focuses on a consistent cadence, IGH and singlespeed are unlikely to be fun for you tho... both styles of bikes have a *lot* of cadence variation.
I generally agree, though I would add that the chain on the IGH gets dirty to.
An IGH allows you to easily add a chainguard to protect your legs/pants (though those simple rings on the outside of the gears seem to work just as well.
An IGH gives you the possibility of adding a full chaincase to protect the chain, your clothing, and anything you lay your bike on (like in your car). However, the only one I've actually seen on a decent bike is on the latest Breezer Uptown. Would have liked one to protect my chain, to...
On my Alfine the gears are, as someone mentioned, spaced fairly far apart and in at somewhat inconsistent spacing. However, after riding the bike for a while it hasn't been a big deal to me.
An IGH is heavier than a derailler, and it puts that weight into the hub on the wheel.
The advantage, of course, is that as the IGH is sealed it's very difficult for water or contaminants to get in or out (though my LBS tells me water still gets in sometimes and mucks stuff up, so it may not be 100% maintenance free).
Buying a bike with an IGH is certainly more expensive than a comparative bike with a derailler.
It's also very different to get the back wheel off than it is on a traditional bike. Depending on the model and mount, it may be harder or may be just as much work but it's definitely different.
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Personally, I have 2 bikes - a high end Specialized Tarmac (road racing bike) and a Civia Highland (straight bar bike). The Tarmac has what you'd expect on a road racing bike. The Civia Highland has an Alfine IGH, disc brakes, front dynamo hub, straight handlebars, fenders, rack, etc.
On the flat with no wind I go 19-21mph with the Tarmac. Under the same conditions, I go 15-16mph with the Civia (doesn't seem to matter if the hub dymamo is on or off, I've tried it both ways).
Up hills I really notice that the Tarmac is faster - it's just so much lighter. I don't have hard numbers, though.
An IGH is great for winter riding where salt and spray get kicked up onto your chain, cassette, derailler, etc etc all winter and just eat your drivetrain. Several different people at several different bike shops where I live who winter commute with a derailler bike say the chain and rear cassette have to be replaced every winter - sometimes the derailler does to. Even if your chain isn't protected at all, with an IGH it's cheaper to buy a new chain and a new single ring on the IGH every year than it is to buy a new chain and new rear cassette every year, not to mention a derailler. And of course, and IGH gives you the option of doing a lot more to protect your chain including a chain guard or a full chain case (well - if they were more available...).
And an IGH might make sense for a rain bike.
But if I lived in Arizona where you don't have to worry about snow, ice, salt, and sand constantly on the road, or rain even, I'd stick with a traditional derailler. It's cheaper, less maintenance, and your bike will be lighter.