Are there more than one flat mount brake standard?

[NHAero]

The close-up photo of the Legor in the Custom Bike section shows a GRX brake caliper with what looks like more widely spaced bolt locations than I've seen before. Are there multiple standards? Or are my eyes playing tricks?

https://forums.thepaceline.net/attac...1&d=1614367684

[RudAwkning]

Originally Posted by NHAero

The close-up photo of the Legor in the Custom Bike section shows a GRX brake caliper with what looks like more widely spaced bolt locations than I've seen before. Are there multiple standards? Or are my eyes playing tricks?

https://forums.thepaceline.net/attac...1&d=1614367684

That bike is using the "fork" standard on the rear. Rear calipers typically mount directly to the frame or to the the type of +20mm adapters in the photos below.

I actually have a carbon fork that utilizes the rear style flatmount spacing.

[yinzerniner]

Originally Posted by NHAero

The close-up photo of the Legor in the Custom Bike section shows a GRX brake caliper with what looks like more widely spaced bolt locations than I've seen before. Are there multiple standards? Or are my eyes playing tricks?

https://forums.thepaceline.net/attac...1&d=1614367684

Looks like they used the front fork adapter standard (70mm spacing) for the rear since it allows easier adjustment. Usually the rear is direct mount for a single size with an adapter flr a larger rotor, whereas the fork is designed for always using an adapter.

[NHAero]

Thanks very much. Glad there are not proliferating standards. I can see "flat mount 386"!

[robt57]

I seem to recall an apartment mount in the UK.

[unterhausen]

Originally Posted by NHAero

Thanks very much. Glad there are not proliferating standards. I can see "flat mount 386"!

I expect a 160mm standard. I have heard that MTB manufacturers are adopting flat mount because they weren't loved as children. Since the rear flat mount is made for 140 and works with 160, 180 probably isn't going to work that well. Or maybe they'll just move on to a different mounting scheme altogether because no production company seems to be able to make a flat mount frame that has flat mounts.

[prototoast]

Originally Posted by unterhausen

I expect a 160mm standard. I have heard that MTB manufacturers are adopting flat mount because they weren't loved as children. Since the rear flat mount is made for 140 and works with 160, 180 probably isn't going to work that well. Or maybe they'll just move on to a different mounting scheme altogether because no production company seems to be able to make a flat mount frame that has flat mounts.

Some of paragon's flat mount dropouts are already starting at 160.

which is important to keep track of since certain calipers, such as those by campagnolo, come in 140 and 160 variants, but based around a 140 mount. So a 160 caliper on a 160 mount, would take a 180 rotor.