I measure 59cm and am not sure whether to...
I measure 59cm and am not sure whether to get a medium or large Bell Sweep. No local shops have them in stock, so I cannot try on.
Any tips on sizing?
I'm in the same boat, falling right between the M & L (59cm) and wear a Medium comfortably.
An important thing to consider is a place that has a satisfaction guarantee. If it doesn't fit you can always return it then.
That being said I am the same way. I measure right at 59 and have found that both the Large AND the Medium fit me fine. Keep in mind that just because your head measures right at 59 doesn't mean you want your helmet to be exactly that. It should fit like a belt, not too tight but not loose.
I went with a large helmet because it still fits snuggly and I have some extra room for the winter when I want to wear a cap or balaclava under it. The choice is yours, good luck!