We have little more information at this time, but according to our sources, Rab died in his sleep on August 22.
Rab appeared on BBC Scotland yesterday where he talked about his achievements, including winning the senior category at the Scottish Mountain Cross Country Championships over the weekend. Previously, Rab had won both the Junior and U23 divisions in the same series.
Rab Wardell got his first mountain bike in 1999, starting a long racing career and eventually becoming a coach. He has won in a range of disciplines from XC to Enduro. He recently turned to marathon racing.

Mountain biker Rab Wardell has died in his sleep at the age of 37 – just two days after winning the Scottish Championship.
Wardell won the Men’s Classic at the Scottish MTB-XC Championships in Dumfries and Galloway last weekend.
The driver appeared on BBC Scotland’s The Nine on Monday night and described how he overcame three punctures to win the race.
The former Commonwealth Games cyclist set a new record for completing the West Highland Road in 2020.
Wardell lives in Glasgow and has been racing mountain bikes since his early 20s, but only turned pro earlier this year.
His victory at Kirroughtree Forest on Sunday was described by the British Cycling Association as “showing incredible resilience” as Wardle managed to catch the early race leaders to take the title.
Recalling his game at The Nine the next day, he said: “It was a bit of a disaster to be honest, but I had to keep playing.
“I think I’m still confident I can catch up to the lead and win, so I’m just doing my best – what else can you do?”
The Scottish Cross Country Association, which runs the mountain bike series, said it was “shocked” by news of Wardle’s death overnight.
A statement on the club’s Facebook page said: “Our deepest sympathies go out to his friends, family and loved ones.
“He will be truly missed by our community and his determination, talent and friendship will live on in the hearts and memories of all of us.
“I’m sure a lot of people will write more convincing words than RIP Rab. Our champion, our inspiration, our friend.”