Originally Posted by
YoungerNow
Other than looking weird, what's bad about it? Given the variety of configurations the KM is intended to support and the geometry they wanted it to have, it makes perfect sense.
Forward facing horizontal dropouts would have probably required them to lengthen the chainstays (and probably the wheelbase) to make it possible to get the wheel in and out.
Vertical dropouts would mean that they needed some other solution (eccentric BB or sliding dropouts) to enable people to run fixed (which is how mine is set up); Either would add cost and complexity and probably reduce durability a bit, while only benefitting some KM users. When I was thinking about building an off-road fixie I looked at the various alternatives and settled on the KM in part because it would let me adjust the chain tension exactly the way I'm used to, without requiring additional moving parts on the frame.
They make it harder to get the wheel in and out (especially with gears and disc brakes, you either have to derail the chain up front or you have the RD wanting to pull the wheel sideways and tweak your nice rotors), you have to adjust the rear brake if you have rim brakes and a flip flop with different gears, and if you're running geared they can be really futzy as having the wheel too far back or forward can mess with the shifting.
Forward facing horizontals would be fine, the chainstays don't have to be more than a few mm longer than they have to be for the tire to fit at all for you to be able to get it out. There's nothing a rear facing horizontal can do for you that a forward facing can't, and I don't really see why adjusting chain tension on them is different enough to matter.