Oops, just realized it's an old thread with a new query. Winter tyres would have prevented 2 of those 4 falls so it's a good idea. However, 1 of those 2 was enjoyable due to the comedy factor and absence of pain.

I'd be concerned with the derailleur more than anything. on folding bikes the derailleur is only a couple inches off the ground and looks like it would be really easy to damage it. on small 20 inch wheels the derailleur is practically scraping the ground. so I don't understand why the vast majority of folding bikes seem to come with derailleurs instead of internal hubs. My Downtube 8fh is the only folding bike I know of that comes with an internal hub.

I have a folder with road tires for regular year round use and then one with knobbies for mainly trails and snow. Were I live it doesn't really snow or ice up all that often and when it does the roads are maintained pretty well anyway so I can't justify buying studded tires, even though they're relatively cheap.
http://www.biketiresdirect.com/produ...d-20-snow-tire

Don't know where you're getting your information from, but there are lots of folding bikes and separable bikes that come with internal hub gears. The Bromptons come with them, the Mezzo's use to have an I4 but I don't know if they still do, Origami has the Fox Model just list a few....

The following folding bikes with internal hub gears (and without derailleurs) are currently available in the U.S.:

Dahon
Curve D3
Vitesse D7HG
Mu N360
Ciao D5

Tern
Link D7i
Link P7i
Verge S11i
Eclipse S11i

Raleigh
Folding i8

Brompton
all 3-speed models

-HANK RYAN-
Norman, Oklahoma USA

Might as well add Bike Friday to the list, of Imports, Hank

Tikit offers a bunch of IGH options. season tikit offers a chain tensioner rear dropout,
with interchangable end fittings for a number of options.

I have one of their Travel bikes , it has the IGH option, frame fitting,
with a chain tensioner [R'off in my case, long left dropout slot
for internal torque stop]
Made in Oregon USA

Hmmm... any opinions on which folder might make the best winter commuting/riding bike? One that can accept big, studded tires I assume.

I limited my list to the brands we carry in our shop. ;) But Bike Friday, Worksman, Citizen, KHS, etc., all have IHG models.

-HANK RYAN-
Norman, Oklahoma USA

I'm only talking about the brands I'm familiar with.