@Sam7919 also, fixed gear riders, indeed the world's most powerful track racers, have never had this "certainty" with their rear-facing dropouts. In other words, this isn't really a problem in practice.

@PaulH I have the impression that when we pay a little or a lot for a bike and bike parts, especially wheels, one of the major things that we’re paying for are tighter tolerances. Ok, maybe “certainty” would really be a word we’d use for aeroplane parts, but still. I’m sure you also have spun each of your wheels with your bike on a stand, and wondered whether the difference in tolerances is the result of materials, skill of the builders, or just their patience (or that of their employers).

With fixed drop outs you don't have that certainty either because the frame is sometimes warped. It's annoying when the rear wheel doesn't teach well, bury it's rideable. With track ends you just align the wheel.

@PaulH does the disc brake sit on the sliding insert? It's a weird mount and strange position (ie notinside rear triangle). Another new standard or something proprietary by Kona?

@gschenk Looks like it does, from that link. I'm surprised, normally theres enough fudge factor in pad placement that it still grips the rotor fine.

"Open" dropouts (for QR/solid axle) with disc brakes are super annoying. So the brake mount better be part of the sliding axle mount.

@Criggie I had a bike with drop outs and disc brakes. Every time you take out the wheel you have to align the caliper again. Because the posts weren't faced perfectly planar this alignment was 15 min of finicking.

@Criggie I suspect "fudge factor with brake pad placement" was something that their legal team did not want to deal with

Sounds fiddly. The only bike I have with disk brakes is pretty straightforward with wheel removal/installs.

So one point is not really data

Is this what we are talking about? (Source: cyclist.co.uk/news/shimano-grx-rx825-di2 )

@Sam7919 That I'd call a track end, becuase it has a mostly horizontal slot.

on this frame, the derailleur is taking up the slack

but if the frame was used as a SS then it would tension the frame by sliding the rear wheel backward or forward

You could also "tweak" the wheelbase a little, longer base for long endurance rides, shorter for reactive racing/crit type rides

But yeah that setup is uncommon as pictured

@gschenk yes. The disc brake mount moves with the whole assembly. I think Paragon makes the parts for the frame manufacturers, so it’s not proprietary. I just dropped my Kona off at the shop last night so I can’t take photos to illustrate better.

@Sam7919 What I'm saying is that track racers now and any cyclist before vertical drop outs had to align their rear wheel by hand and eye and everything was ok. If the world's most powerful cyclists (track racers) can align a wheel and have it stay in place, then the rest of us are probably ok too.

yep - the only time I had problems with wheels slipping in dropouts, was when both the frame and nut were work-hardened and slid on each other under leg-pressure.

@Criggie and that's of course under Criggie's leg power, which is quite the edge case

pffft. That was a 20" wheel, and I was towing a trailer full of tools, which was sitting in a pothole. I was also in a low-low gear like 28:42. Just taking off normally takes an effort, but being in the hole make it resist more. Leg power was not the only cause.