IF you think cycling for 600 kilometres on two wheels is tough, try riding on one.Caulfield's Matthew Thomas decided the task of cycling in the Great Victorian Bike Ride wasn't challenging enough so he upped the ante by riding on a unicycle."I was going to ride anyway because I've been involved in a few Great Victorian Bike Rides before and I thought this might be something different," he said.Mr Thomas has been riding unicycles for more than 20 years but this is the first time he has attempted the mass participation ride with only one wheel."I'm riding my unicycle 500 kilometres across Kenya and Tanzania next year so this will be great preparation for that," he said."I think the roads in Africa will be a little less smooth than here though."Mr Thomas was part of the army of cyclists that descended on Mortlake yesterday for the third day of the popular annual event.More than 4000 Great Victorian Bike Ride participants converged on the town's Tea Tree Lake Park after making the 60-kilometre trek from Cobden.Veteran cyclist Bruce Casey, who has participated in 18 consecutive Great Victorian Bike Rides, said conditions for the Cobden to Mortlake ride were ideal."It was a great stretch of country - the sun was out and it wasn't as windy as the second stage from Rokewood to Cobden on Sunday," he said."The south-west of Victoria has some nice flat terrain, which means you can take in the scenery more and you don't have to push yourself as much."Mr Casey said he was looking forward to the fourth stage of the event, which kicks off this morning. Today's leg today will wind its way from Mortlake to Dunkeld, which lies at the foot of the Grampians .But some participants proved that riding across the state wasn't a solitary experience, with tandem bike riders adding extra pedal power to the event.Mt Evelyn husband and wife team John and Denise Compt proved more legs made lighter work by riding a tandem bike together across the district yesterday.Mr Compt said he decided to ride in tandem this year after his wife sustained minor injuries one week before the ride."We normally ride on separate bikes but Denise injured her neck slightly so we thought we would share the workload," he said."The secret to tandem bike-riding isn't the ride itself but actually counting down before riding off," he said."If you don't pedal in sequence it won't work."