Laura Ward had cannabis, diazepam and amphetamines in her system when she hit Aiden Platt, 20, in Barnstaple, Devon.
Ward, 30, of Fleet, Hampshire, admitted causing death by careless driving but was spared a jail sentence because she has a young child.
Campaigners have set up an online petition and say they will stage more protests until the law is changed.
Protester Ben Reed, who was among those taking part in the "ride out" demonstration in Barnstaple, said Mr Platt was "one of our own, a local lad and a biker".
He added: "His life was taken but no justice was served."
Ward was handed a 20-month jail sentence but it was suspended for 18 months because she had a five-month-old son at the time of sentencing.
Footage was shown to the court of Ward's car pulling out at Sticklepath Hill without any warning with Mr Platt being thrown into a traffic light post on 2 August 2015.
Protester Pam Douglas said: "It's too lenient, she should have got a prison sentence. The 18 months, suspended, is no sentence. Aiden's parents have got a full-life sentence now without Aiden."
Devon and Cornwall Police appealed against the sentence but the Attorney General but turned it down saying he did not believe there was a realistic chance the court would find it unduly lenient.
Sgt Rob Kelland from Devon and Cornwall Police said: "Three illegal drugs were found in her system, it doesn't send out the right message to people considering taking drugs and driving."
The Ministry of Justice said it was consulting on increasing jail terms for drug and drink driving, but said it was ultimately up to independent judges to pass sentence on the facts of the case.
Aiden's mother, Mandy Glass, said: "Everyone is a vulnerable member of the public when a driver gets behind the wheel of a car drunk or under the influence of drugs, whether you are a biker, cyclist, pedestrian or car driver.
"I just hope at some point the justice system in this country will acknowledge that and start to give sentences that reflect the seriousness of the crimes committed."
More than 500 bikers have joined a rally calling for tougher sentences for drivers who crash while on drugs.