Once it starts on the road you could stop the bike, get off and lift the bike then crank the pedals by hand and see if you can better locate the noise.
Here's the thing - I cannot reproduce the sound without being on the bike. It will go tick tick, I'll get off the bike and crank pedals / spin wheels and it just won't make the noise. I've put it on the stand and can't get it to do it there either.
It's like taking your car to the repair shop with a strange noise - it never makes it while the mechanic listens.