I actually mean the vertical rear ends.
Those bloody vertical ends.
In the picture on your left you can see a back part of a frame with the rear ends, in this case horizontal.
That’s where you insert the back wheel, inserting the axle of the hub in the forks and tightening the bolts so the wheel doesn’t run away.
So far so good, no?
The important thing is that the wheel doesn’t run away while you are riding because then you will fall, you will break part of the bike and hurt yourself. Normal, so far.
The sense for horizontal is to allow the correct tension and alignment of the chain, playing with the wheel while mounting it. A normal thing.
In the last few years, they have imposed the umpteenth nonsense, which is referenced to the wish to change something that doesn’t need to be changed; they introduced vertical ones.
In this barbarical species of ends, the entrance for the wheels axle is towards the ground.
In this case it is nearly impossible to tense the chain in a proper way; you need a chain tender that is part of the back gear block.
Their sense is exclusively related to the needs of bicycle teams; to replace a wheel or a puncture during a race is far faster, during a race. But we are talking tenth of seconds not seconds.
Going one step ahead they went three steps backwards; to get the right tension of the chain on a fixed bike you have to rely exclusively to luck and to your army of cogs and crowns; you need to find the exact (at the tenth of millimetre) combination between the number of mesh, number of teeth of the cog and the number of teeth of the crown. Three of my bikes have frames that are maimed by this absurd new item, and to make them fixed required quite a lot of genius. In one case I had to file a frame, because of that bloody half millimetre that didn’t want to disappear on it’s own.
I strongly dislike vertical rear ends.