Originally Posted by
special_k
these two sizes are common for most folders.
Are there advantages to one over the other?
Which would you recommend?
There are actually four sizes in common use, but bike wheel size naming is confusing, so two of those sizes are called "20 inch" and two of them are called "16 inch".
The four sizes are:
305mm
349mm
406mm
451mm
Birdy also uses the close to 349mm size of 355mm and called it 18inch.
406mm has the most tire options by far.
349mm and 305mm are more compact so they let bikes fold down smaller. 305mm is used by Dahon and Downtube, while 349mm is used by the Bike Friday Tikit and Brompton.
451mm is mostly used on the performance oriented Bike Fridays, but I've also seen Swift Folder use it (not on the Xootrs) and some Raleigh 20s used it. 451mm is nice because it still fits into 29-30" suitcases but doesn't require chainrings that are quite as large. The downside is that only narrow high pressure tires are available for it.
I wouldn't get too hung up on wheel/tire size. Pick the right bike for you and let the wheel size follow. I've owned three folding bikes (Swift Folder, Bike Friday NWT, and Bike Friday Tikit). I don't notice any significant differences with the Tikit's 55mm smaller wheels despite my dislike of the stock Schwalbe Marathon tires.
alex