I like the term "kit" when it refers to an individual athlete's race gear. But I always use "uniform" when referring to the one outfit the whole team is wearing (hence the word uniform). That said, I think "kit" is catching on because it is such a short word and it brings a bit of Euro style to your comment.
But for me, these examples are probably typical of my usage:
"If I am racing an triathlon, it is nice to have a kit that fits well and has enough pockets for all the gels. The kit I wore last year was nice but a bit baggy."
"BYU has a good uniform but it would be even better if they had an all white version for home meets. I'd like to see a uniform like that for next year."