What is the general standard length for cranks on a 55cm track frame? It will be used for general track riding and racing. Would 172.5 be too long? That's my length for a road bike but I thought that shorter would be better for a track bike on steep banking. The bike has DA cranks so they are a good selling point but not if they are too long. Thanks.

From what I've heard around here, 165 and 170 at most are the norms for a track bike.

On a track frame it usually a matter of preference but on a road conversion it can be a matter of safety. This is because the BB height is higher on a track frame than a road frame. This is not to say that longer cranks won't work for you, you just need to watch out when leaning into a turn. I have 170's on a road conversion and have only scraped a pedal once and luckily did not go down (scared the #$%$ out of me though). Hope this helps

Also, actual track bikes often sport longer cranks than they might if they were for street use. The corners in a velodrome are well known, so they'll be tuned to clear the boards, but often not much more. Street cornering is obviously less predictable.