He was swept along for around 100 metres before managing to cling to a rock and alert the rescue services, the Blick newspaper reported.
It quoted police in the canton of Graubünden as saying the spectacular accident happened on Saturday afternoon as the man was cycling along the left bank of the river from Untervaz to Haldenstein.
After losing control over his bike close to a wind farm at Scalaripp he and it plunged into the fast-flowing river.
Fortunately he was able to cling onto a rock and call for help using his mobile phone.
The Rega rescue services managed to fish the man out of the river using a winch and helicopter him to hospital in Chur where he was found to have suffered no more than exposure, shock, bruises and scratches.
The bike could not be recovered.