How useful/valuable is internal cabling? I'm in the market for a new bike. I'm not a club rider but a utilitarian one: I commute on my bike, visit friends and run errands. On average I probably ride 2-4 miles per day, almost entirely on good roads. Very occasionally I'll ride on a rough track like a riverside path.

I picked the model I was interested in and asked a cyclist friend if he'd go for that, or a more expensive version. The extra money buys:


An aluminium fork instead of a steel one
A few extra gears
Internal cables


The extra gears are of no value to me. I tested both in the bike shop and couldn't tell the difference between aluminium and steel forks on a good road surface, which is where I do almost all my riding.

That leaves the cables. I can see that internal cables look much neater, but my friend says they'll save me money on cable replacement because they won't get dirty from road spray working into the internals.

The price difference is £100. Are they really going to save me £100 over the likely lifetime of the bike (let's say 10 years)?
One difference that internal cables make is if you transport your bike by car or have to haul it around by hand.


Because the cables are inside the frame, they are less likely to get pinched by the clamp on your car-mount (especially if you use a trunk mount that clamps the top-tube). This is also true for car/bus bike mounts that clamp the down tube.
If you are carrying the bike up flights of steps, having internal cables means your hand/shoulder isn't rubbing the cables when you carry it by the top-tube. 
If you have external cables on your downtube, they can get banged a bit if you lock your bike with a U-lock through the front wheel and triangle. Nothing critical.


These are all really, really minor. Internal cables are more about the aesthetics than anything else.