Carrier block adapter for brompton saddle with cateye mount

thingiverse

This is a Brompton Carrier Block Adapter for Brompton Seat with Cateye Mount. The Cateye screw mount isn't very strong, so an extra mounting point is needed. I drilled a 5mm hole at the top of the seat post and used a long thread rod to attach this adapter and seat post together. Cable ties were used via the square holes to strap the adapter to the seat rail in case of mount failure. It's not straightforward but an easy DIY project. It would be useful for people who have an electric Brompton that lost the carrier block option. Before you start, use it at your own risk. I personally tested it for over 200 miles with no issues. Materials needed (read carefully to the end before starting): M5 thread rod, 200mm long (needs to be cut to the right length depending on seat position) M5 Hexagon Connecting Nuts (mine is 25mm in length; you could use multiple M5 nuts instead) M5 lock nuts M5 Spring washers and ring washers M5 12mm socket cap nut M5 50mm Socket cap nut Tools: M5 drill bit (a normal drill is fine, but a press drill would be better) Ruler Instructions: 1. From the top of the seat post, measure down 7mm and mark a dot. 2. Drill through the mark across the seat post so you'll have two holes on both sides. 3. Mount the adapter using a spring washer and M5 12mm with an Allen key at the end of the saddle. 4. Mount the Brompton carrier adapter using a M5 50mm socket cap nut, mounting only the top screw hole of the mount. 5. Put the saddle back on the seat post. 6. Put the M5 thread rod across the bottom screw hole and the seat post hole. Measure the length and cut it to the right length so both lock nuts can be screwed on for both sides. Alternatively, you could put everything together and cut it after. 7. Refer to the photos about mounting. You need to fill the gap between the seat post and the mount adapter using connection nuts and M5 nuts. This helps to stop shaking and support the weight of the mounted bag using the seat post rather than the saddle mount. Starting from the front, the sequence is M5 lock nut > spring washer > ring washer > seat post > M5 connecting nut/M5 nut(s) >M5 lock nut>ring washer > mount adapter > Brompton carrier block > ring washer > spring washer>M5 lock nut. 8. Use zip ties to secure the mount adapter with the seat rail in case of saddle mount failure.