Dengfu R13 Rear Brake Mount

[quarkrad]

I have seen some posts on the R12 and not absolutely certain if rear brake mount point is the same on both frames.  My intension is to fit the Shimano 105 di2 groupset onto this bike - the rear disc brake caliper being a BR-7170 flat mount caliper.  My issue is that the front forks have threaded mounts points for the front caliper (nice and secure) but the rear has just slots - as shown in the attached picture.  I also need to use the disc brake mount adapter as I'm using 160 rotors.  I obviously need longer attachment screws than those supplied but I'm wondering how other people who have used the R12 or R13 frame have made a secure connection for the rear caliper.  Any advice much appreciated.

[bigApple]

The short bolts supplied with the adapter are for attaching the brake body to the adapter. The screws for the frame, which are screwed through the frame into the adapter, must be purchased in the correct length.
For example...

Frame diameter:
10 mm
Screw length:
23 mm
Manufacturer number:
Y-8N208000

15 mm:
Frame diameter:
15 mm
Screw length:
28 mm
Manufacturer number:
Y-8N208050

[bigApple]

As in the article description here:

https://www.bike-components.de/de/Shimano/Befestigungsschraube-HR-Typ-C-fuer-Flat-Mount-p45063/?o=1000141923-schwarz-20-mm&delivery_country=DE&upid=google&utm_source=google&utm_medium=cpc&utm_campaign=20412471827&utm_content=157110081292&utm_term=&gclid=CjwKCAiAp4O8BhAkEiwAqv2UqEaJ0bjm152lIMYaZlxPGOzf_hx1M1a6EIKUHGAqi7gKP4JzbTUNjRoCNlkQAvD_BwE

[quarkrad]

Thank you for your time - parts ordered