I HAVE THE REGULAR BIKILA AND THE LEATHER TREK LS VERSION. THE BIKILA ARE DEFINITELY GEARED FOR ROAD RUNNING IV'E TAKEN THEM ON TRAILS AND YOU REALLY HAVE TO WATCH AS SMALL STONES CAN BE QUITE PAINFUL WHEN STEPPED ON WITH THEM. I GOT THE LS EVEN THOUGH VIBRAM MARKETS THEM AS MORE FOR CASUAL WEAR BECAUSE I RUN MAINLY ON BRIDLE TRAILS AND I LIVE IN NORTHERN OHIO WHICH GETS QUITE COLD IN WINTER. THE TREK LS HAS LESS OF A BAREFOOT FEEL BUT OFFERS GREAT PROTECTION AGAINST STONES AND THE LIKE. THE STANDARD FABRIC TREK HAS THE SAME LUGGED SOLE AS THE LS VERSION BTW. I'VE RUN IN COLD WEATHER IN THE BIKLA AND THEY ARE NOT WATERPROOF AND IT CAN BE UNBEARABLE ON LONG RUNS IN BAD WEATHER. LIKE I SAID I BOUGHT THE TREK LS SORT OF WATERPROOFED IT FOR WINTER AND USED ININJI SOCKS THIS WINTER AND LOVED THEM. THE WATERPROOFING JOB WAS'NT PERFECT BUT IT WAS WAY MORE COMFORTABLE IN COLD WET WEATHER. THESE ARE 2 VERY DIFFERENT SHOES IN TERMS OF PURPOSE AND IT SOUNDS TO ME LIKE YOU HAVE YOUR ROAD SHOE IN THE BIKILA LS. HOPE THIS HELPS
i bought some kso online using the sizing chart, i have 10" feeet so i went online & scoured the net for a pair of m39 which i found only to find they were way too small. i went up a size m40 & found they fit just right. i bought the bikila in the same size & thought i made a mistake. the bikila has the same sizing according to vff but just be aware they will feel tighter than a kso of the same size. the design of the bikila is a stiffer, especially in the toes which will not flex as much. when i received mine i thought i had to size up but i gave them a shot because i like a tighter fit & after 4 or 5 runs i liked them alot. i personally would recommend a tighter fit as i think the bikila will "break in" & stretch in a short period of time, they may seem uncomfortable at first but i found them to be an upgrade from the kso. my experience with the sizing is to go 1 size up from the suggested vff size for the kso or the bikila. the bikila & kso are pretty much the same size wise but the bikila has a way tighter feel that might convince some to size up again. it's a pain buying these things online to find the right size & "dial" it in so to speak, especially when they are out of stock in smaller sizes.
i thought my bikilas (m40) was way too tight compared to the kso which i also have in the same size. but i've run 4 times in them & they seem to stretch out,my last run they were very comfortable felt snug & just right. i think a lot of people run into this problem & my guess it's because the front of the bikilas especially the toes were designed to be stiffer than the kso, i just can't flex my toes as much especially upwards. i also think that the clear pieces of plastic on top of each toe might contribute to the overall tighter feel. i personally like a tighter fit for both versions as i think a loose fit would result in blisters from sweat & friction, they are after all gloves for your feet.