Shutter speed issue on Canon 7D when using studio strobes

Los Angeles CA

Description

Any Canon 7D users here? I'm helping a friend figure out why his Canon 7D has black or white bars if shutter speed is below 1250 when shooting with strobes (Alien bees, 3 separate ones). I know shutter is delayed when studio flash lights on every DSLR but 1250 seems way too high. My Canon 5D mark ii only goes up to 250. I don't know Canon 7D that well and can't seem to find any answers online. Any help would be much appreciated. Thanks