Perth has recorded a big — and unexpected — decline in the number of people riding bikes.

The annual count of city riders has revealed an average 10 per cent decrease in the number of cyclists riding to and from work and at weekends.

Transport officials have blamed the downturn on the weakening economy, resulting in high office and retail vacancy rates reducing work trips to the CBD.

Perth’s cycle network is monitored by 41 permanent bicycle counters on paths across the metropolitan area, including 11 that ring the CBD.

About 10,000 riders cross the CBD ring every weekday, falling to 7600 at weekends.

Based on the latest 2015-16 count, the biggest decline in bike numbers was at Narrows Bridge East, with a 30 per cent reduction to 538 riders a day.

At the city’s busiest site, Narrows Bridge West, the fall was only 2 per cent, to 2256 daily riders.

The Department of Transport’s acting executive director for integrated network planning, Craig Wooldridge, said the latest count data did have a silver lining.

“The extension to the Midland principal shared path in recent years has resulted in increases in usage,” he said.

“This demonstrates that safe infrastructure that is connected to employment centres attracts new cyclists for a relatively small investment.

“The PSP expansion program works that have taken place on the Midland and Fremantle lines appear to have attracted a mix of recreational and transport-related cyclists, with increases in cycling numbers in areas away from the Perth CBD rather than declines.

“A key lesson from recent works is the need to work more closely with the community to promote the travel and recreation options opened up by the PSP extensions.

“It is pleasing to see a good diversity of new cyclists in every day attire using facilities such as the Beaufort Street bus/bike lanes.

“In the future the bike counters will need to be expanded to cover these types of roads to capture more data.”

Bicycling WA chief executive Jeremey Murray said connected and safe routes were the key to encouraging more people to ride bikes. He said this was evidenced by the success of the Midland PSP extension.

“We are keen to better understand the reason for the falls in cycling participation,” he said.

“While some decline can be attributed to the economy, there would appear to be other reasons in play.

“We know perceptions of safety and riding on the road with cars are barriers for many people, particularly women. We all need to be doing more to encourage people to get out on their bikes as it’s cost-effective, healthy and fast.”