Paul Martin, 37, from Stroud, died when his trail bike was hit by a train at Frampton level crossing in May 2014.
The Rail Accident Investigation Branch (RAIB) report also found signs did not explain trail bike riders were prohibited from using the crossing.
The RAIB has recommended Network Rail improves the "content" of its signs.
Mr Martin was the last of three trail bike riders to reach the level crossing along a track, near the village of Sapperton on 11 May.
Despite signs warning "vehicle users" to use a telephone at the crossing to find out if it was safe to cross, none of the riders had.
According to the RAIB report, the signs had failed to "grab their attention sufficiently" and the bikers had "believed" they could cross safely by "looking for trains".
"The riders did not know that a curve in the railway meant that they could not rely on seeing an approaching train early enough to decide whether it was safe to cross," the report stated.
As the Swindon-to-Gloucester passenger train approached the crossing, a warning horn was sounded but the report said it was "likely" the bikers did not hear it because of their "full-face crash helmets" and "noisy" trail bike engines.
Although the RAIB found there was "no requirement" for signs to include references to trail bike riders, it has recommended that "content and positioning" of signs be improved.
It has also recommended that Network Rail "seek a better understanding of actual (not only permitted) use of level crossings" and raise awareness of where people are "not permitted" to take vehicles onto level crossings.
A man killed at a level crossing in Gloucestershire may not have heard the train's horn because he was wearing a crash helmet, a report has found.