I have a Dahon S1 (single speed) that arrived today and one of the first upgrades I am looking at is getting better quality wheels. The coaster brake on the stock Dahon wheels are a joke and basically prevented the wheel from spinning freely. I ended up removing the coaster brake and adjusting the cones on the hub so now it spins really fairly well and doesn't seem to give rolling resistance like it did when the coaster brake was in place, but the cheap tin caps over the bearings have already warped and I suspect that dirt and sand will quickly take their toll on these wheels. Overall the quality of the wheelset that comes with the bike is a joke.
I plan on keeping the bike single speed but would like to get a wheelset with seal bearings if possible. Will a BMX wheelset fit? Dans Comp sells a few sets with sealed hubs ranging from cheap to $$$$$. I have also seen what looks like 20" road wheels used on kids road bikes. Any ideas on using these?
On a side note, the bike rides very much nicer than folders I have ridden in the past. The geometry feels like something between a mountain bike and a beach cruiser and is very comfortable to ride. Took it out for several miles once I was done with the coaster brake project and it would seem that this bike and I are going to have a long happy life together.