Did you notice a decrease in breaking performance when you put on the wheelsmith carbon rims? I'm also going out on a limb and guessing they are heavier than the Brompton rims (cooler granted).
These are SMC rims, a lot lighter (760 grams) braking is around the same as alloys in the dry, just wet is a little bit sketchy but that's will all carbon rims.
Did you notice a decrease in breaking performance when you put on the wheelsmith carbon rims? I'm also going out on a limb and guessing they are heavier than the Brompton rims (cooler granted).