hmmm.. I have a 16" 456 and just purchased a co-pilot child seat..

It comes equipped with a Blackburn EX-1 rear rack but the rack fouls on the brake mount..

I'm aware that I can purchase a disk specific version of the rack but it doesn't look to me from online pictures and diagrams as if this version will solve the issue..

Does anyone have experience of mounting a rear rack onto a 16" 456?

I've used one of these on a 456, with panniers not a child seat.

I tried and failed to get a EX1 rack to fit onto my wife's 16" sliding dropout Inbred, what ever I did the rack would push on the caliper. Not sure how the geometry of the 456 compares? In the end we bought a different (cheap) bike to fit the child seat onto.

I have just bought a Co-pilot child seat and had to buy the disc compatible EX-1 rack. Fitted it in 5 mins to my 456. It does solve the problem. Standard Ex-1 rack included with the seat, won't fit easily, but could be bodged to do so.