No. On the other hand, you don't need to. Scan a tag. Send the data. The receiver time stamps the receipt of the tag, defining the start time. Scan a tag on the other end to record the end time for that tag.
This is how I had originally planned for the system to work but was concerned with latency issues from sending and receiving the data hence the idea to add a real time clock to the transmitter unit. For simplicity's sake would it be ok to assume that there is negligible delay from when the start gate is triggered and when the receiving Arduino is actually aware that it was triggered? At the very least would this delay be consistent for every rider throughout the day?
Thanks,
-Jason