Originally Posted by rickybails
I asked Peter Reich what the issues were with fitting 451 rims and he thought that the R556 brakes were the only ones that would fit. He also said the the bike was originally designed for both 406 and 451 brakes and at the time there was only one brake that was long enough reach: Dia Compe 'big dog'. When Dia Compe stopped making these brakes this effectively left removed the option of selling the Swift as 451-compatible. That is until the R556 brakes came out.
Thanks for the follow-up. Also keep in mind that the holes for the fork and rear triangle are too small for the 556 brakes. I did have to gently dremmel/bore out the hole a bit.