I am 6 ft, 200 lbs; 44 shoulders; 44cm handlebars are a really good fit for me. 46s look huge to me but if you find that more comfortable, go for it. By the way, are you sure your fit issue is handlebars. 53cm frame for 5'10" person seems kinda small and a too small frame would make one feel pinched a bit. I would think 56cm or even a bit larger would be more your size.