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I came across this as they came standard with some OE SRAM brakes from Alpkit. Just 2 thick spacers with 12.5mm and 7.5mm printed on them. That's really neat but probably not new? Any downsides? Rigidity?
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Slightly more faff for the OEM/manufacturer to put together, but that's always been the case with those adapters where the bolts went straight through into the frame needing conical washers etc to allow for the angles.
Somewhere in a parallel universe the industry took the sensible approach and stuck with IS mounts, standardized the caliper size, made all forks and frames 150/175/200/225 as appropriate for their use, and machined them flat/accurately so they didn't need shimming. Because this abomination is not an eleagant solution to either an engineering or a manufacturing problem.
Is that front spacer fitted correctly?
The lower conical washer on the "rear" stack seems to be sitting deeper into the spacer - suggesting the top is concave. But the front lower washer seems to be sitting proud on the front spacer - as if the spacer has a flat surface pointing up. May just be the angle of the photo.
They shift any bending load to the bolts, almost 100%, rather than sharing it with the central web of the adaptor.
So only a few mm possible.
There's a well known but incredibly badly informed weight weenie who was doing similar, but with CF tubes and a discs that were too big for the frame and forks. So 30 mm long carbon tubes...
That's a horrible solution. Mounting brakes radially makes them nice and solid, more so than the old IS way. Those spacers and bolts will introduce flex, vibration and a loss of breaking power/finesse.
Nasty.
They're just the standard adaptor but without the joining bridge between the two parts. That joining bridge helps spread braking loads so they're not as strong as regular adaptors. Go too far and you can bend the bolts.
Somewhere in a parallel universe the industry took the sensible approach and stuck with IS mounts, standardized the caliper size, made all forks and frames 150/175/200/225 as appropriate for their use, and machined them flat/accurately so they didn’t need shimming.
IS mounting is crap, an absolute pain if your frame/hub combo puts the disc too far in or out, let alone if you want to use a different wheel. The answer (as it always has been) is Radial mounting with grub screws to dial in the last/right if the caliper like Hayes used to have. All you need then is straight adaptors with +10/20/25/30/40mm etc regardless of what brakes you use. But it'll never be used as it looks odd on the rear, hangs the caliper lower to the ground on forks (was more of an issue with 26" wheels hence why Post Mount is offset) and requires slightly higher tolerances.
That's awful. Seeing as its not 2012 any more, why aren't frame makers fitting postmounts in places where they'll directly take a 180 or 203mm disc?
Not my first choice of brake mount but I'm using one on the back of a carbon hardtail where the alignment is a little off and the stays are too tight to get a facing tool in there. Works perfectly now.
Its useful where you don't trust the post alignment / cant be bothered to get it right. For an OE they're no more difficult to fit as you get the bolt pre-fitted with a small o-ring to hold it in place.