Toowoomba rider Jared Graves after the elite men section of round seven of the 2017 XCO National Series at the Oceania Continental MTB Championships at Jubilee Park, Sunday, March 12, 2017.

Toowoomba rider Jared Graves after the elite men section of round seven of the 2017 XCO National Series at the Oceania Continental MTB Championships at Jubilee Park, Sunday, March 12, 2017. Kevin Farmer

CHAMPION Toowoomba mountain bike and BMX rider Jared Graves has been struck by a brain tumour diagnosis, after returning home from competing in the Enduro World Series in Canada.

The former Olympian broke the news to his Instagram followers yesterday.

"Some news of the not so awesome variety. To cut a long story short, since getting back home from Whistler I suffered a couple of seizures, and woke up from one last Thursday morning to paramedics taking me off to hospital," he wrote.

Mr Graves said tests and scans showed he had a brain tumour.

"So for now more scans and doctors appointments and scans over the next week leading to surgery within the next approximately 10 days," he continued.

"The plan at the moment is to then start chemotherapy. Not sure what else to say for now, it's all hit so fast....needless to say I won't be at the last 2 EWS rounds this year as this new battle begins."

The news has shocked the biking world, with messages of support flooding social media from fans and fellow riders.