From a personal POV I’d say it’s only really lacking in two key areas. The focus seams a little soft - tracking action shots are always a tough call but it always seems more dynamic if the focal point is pin sharp even if it is at the expense of the background - this adds to its dynamic appeal too, secondly it would be the slightly flat contrast both in colour and luminosity - that could be easily fixed in post or RAW whereas the first matter can't be. At least not effectively. Hope that helps.
I would say the color looks like late afternoonish, say, 4:30PM .. and one of those funny, undecided skys
If I wasn't experiencing phantom computer problems, I would say send me the original to play with .. not that I can address either of the two issues Phil mentioned ..
if you go occasionally .. and you have quite a bit of zoom left in your lens barrel .. I would try a different angle and a significantly tighter zoom .. like, maybe a head-on oblique angle as they round a corner .. focused on the consternation and perspiration of the front-runners .. let your depth of field soften the 'also-rans' ..
you might have to pre-focus and let them enter 'the zone'
Not much to add to the above Rob ... looks like you succeeded on some levels ... as in and what immediately strikes me, a full frame of the riders and a well balanced composition in that regard.
But, yeah ... a tad flat on the lighting and colours. :o\
Heyyy!! I know!!... use a ginormous flash??
Sorry, lol ... couldn't resist trying ... trying to add some levity. :oP
thanks in advance.
linkeroo