There were 693 incidents in 2015 compared to 2014's seven-year high figure of 749.
Incidents recorded by the police reveal 25 people died in 2015, slightly down from the previous 12 months.
But road safety charity Brake said the number of motorcyclists involved in serious accidents was too high.
"In Wales motorcycles make up 0.2% of traffic on the road but account for 41% of deaths and serious injuries," Brake spokeswoman Lucy Amos said.
"Motorcyclists, along with cyclists and pedestrians, are among the most vulnerable road users.
"That's why it's so crucial drivers remain vigilant at all times, and do everything they can to look out for and protect people around them, whether they're on motorbikes, bicycles or on foot."
Travel safety partnership GoSafe said it was working with Wales' police forces, fire services and local authorities along with the Welsh Government to "engage with, and advise road users".
The Welsh Government said the safety of road users was a priority but it wants more help.
A spokesman added: "The latest statistics show that there were fewer motorcyclist casualties in 2015 than in the previous year which is to be welcomed, but we want to see that reduction continue further still.
"The Road Safety Framework for Wales sets out the actions we, along with our key partners, are taking to increase the safety of our roads and reduce the number of casualties.
"What's clear, however, is that government cannot do this alone and we must all share a responsibility to ensure that we use our roads safely."
The number of motorcyclists killed or injured on roads in Wales has dropped for the first time in five years, official figures show.