Do tracks allow you to use a road fixed gear conversion? (Assuming you've removed the brakes).

Depends on the track.

Anyone know about Kissena in Queens NY?

Death by braze-ons.

If your actually serious about racing, it would be good to invest in an actual track bike, with actual track geometry. Depending on the track, you might need the higher bb and obviousally shorter cranks.

It all depends on how steep the banking at the track is. This affects how high your bb needs to be. At my local indoor drome (Burnaby) the track is only 200 m long and hence has sharp turns and super steep banks, so conversions are not allowed.

Well if you can't then it's pretty inexpensive to get a track frame or a Mercier complete.

the problem being it's hard to tell if your serious before you've raced some.

Most tracks have rentals you can use if they won't allow conversions.

This can't be stressed enough. An off-the-shelf Kilo TT or Hour from Bikes Direct is about as much or cheaper than many conversions, and would suit someone getting into track racing just fine. And the value of these bikes seems to EXCEED their original price, so there's really nothing to lose.

RENT
rent a bike for the first few times
I've yet to find a track that doesn't have rentals