Hartman - the club's second pick in the recent NAB AFL Draft - came to grief on Monday morning when he locked his brakes near the end of a steep descent.
He ended up flipping over the handlebars of his mountain bike and disappearing into the bushes beside the track.
However, he soon picked himself up and emerged from the shrubs wearing a broad grin.
"Poor old Brad went head-over and straight into the bush," Geelong recruit Hamish McIntosh told AFL.com.au.
"I think he had a rough day. He had a couple of tumbles. But he was good. He's a really good kid and he's training hard."
Earlier in the day McIntosh had also come off his bike in almost the exact same spot that Hartman came to grief.
"Blokes over six foot five shouldn't be on a bike, full-stop, so it's not really my strength," McIntosh joked.
"I was pretty nervous. I haven't been on a bike like that for about 10 years.
"I was coming down the hill and I didn't really know how to work the brakes properly on the old mountain bike and I went straight into the trees.
"Lucky enough for me I ditched the bike just before I went into the trees. The bike was no good, but I came away unscathed.
"It is pretty hard for the new guys coming in because a lot of the guys here have been doing a lot of bike riding.
"I've come in having not done a lot at all and I'm sure Brad's exactly the same, so we were very rusty and we've obviously showed that today with a couple of bingles."
Hartman's mishap came during a teams challenge that involved running, road cycling, mountain biking, kayaking and a number of off-beat challenges like putting together jigsaws and completing sudoku puzzles.
The players also had to take part in a competition to see who could keep three balloons in the air for the longest time.
Geelong's first- to seventh-year players have been at Falls Creek since Wednesday. The camp runs until December 21.
Adam McNicol covers Geelong news for AFL.com.au. Follow him on Twitter at @AFL_AdamMcNicol
