That bike does not have bosses for down tube shifters. If you have the track model is more than obvious why not, if you have the road one is because bikes aren't using d/t shifters from the mid 90's maybe, I would not try to put d/t shifters to it also, bad idea. Clamps are too small also because the downtube is oversize. U can use shifters in the handlebars/stem or something but that would really kill the bike, you are the owner tho.
That bike was designed to be used with brifters.