THEY are supposed to be sharing the road - but cyclists and motorists are sharing the anger as frustration between the two road users reaches fever pitch.

From vitriolic outpourings on online forums, heated letters to the editor and video evidence posted on dedicated social media sites, both parties are increasingly coming to blows as the number of motorists and cyclists swell on South Australian roads.

And the international cycling showcase Tour Down Under almost brings both tribes close to war each January, with claims that the Lycra clad take over the streets and counter claims that drivers refuse to show respect to their fellow road users.

TELL US BELOW: How can we stop this intolerance?

Motorists moan that cyclist are a law unto themselves and are not punished when they break it.

But a police crackdown on rogue riders shows a big increase in fines for red light running, riding on footpaths and failure to use lights at night.

The number of riders fined or cautioned for ignoring red lights or illegally using a mobile phone almost doubled to 447 in the 12 months to June, compared to the previous financial year.

The number of riders caught cycling on footpaths also rose from 234 to 296 and riding without the required lights was up from 1388 to 1660 in the same period.

Only fines for failing to wear a helmet were steady, averaging just over 3,000 a year for the past five years, police figures obtained by The Sunday Mail show. Officer in Charge of Traffic Support Branch Superintendent Bob Fauser said almost 7000 fines and cautions were issued to cyclists last year as police increasingly target riders thumbing their nose at the law.

"Police focus traffic enforcement activities on those behaviours which contribute to death and serious injury on our roads - including increasing our attention on cyclists,'' he said.

"But all road users whether it be cyclists, pedestrians, motorcyclists or car drivers all need to demonstrate tolerance and share our roads in a manner that keeps everyone safe.

Motorists and cyclists are increasingly using dashboard and helmet-mounted cameras to film confrontations or capture each other allegedly breaking the law.

Vision of cyclists has been posted to website Crap Adelaide Drivers accompanied by comments such as "Lycra maggots".

The site administrator, who only gave his first name Kym, said it was not his role to censor spiteful comments.

"The content posted may anger some people, as they're tired of seeing cyclists openly flout the road rules. It's something most drivers can relate with, particularly around the TDU time, when MAMIL (Middle-Aged Men In Lycra) are at their highest.

"I think something you have to consider, we've posted tons of content of bad drivers, calling them idiots and dumb asses, is that any different to doing the same with cyclists?"

Cycling and motoring groups welcome the stronger police focus on riders running risks by breaking the law, saying failure to share the roads can be a deadly business. Bike SA and the RAA are also calling for patience from both parties as the number of motorists on our roads increase so too does the number of cyclists.

While the number of licence holders increased by almost 70,000 between 2008 and 2012, the number of people cycling to and from the CBD has almost doubled from 5,000 to more than 9,000 between 2003 and 2011, according to data compiled by Bike SA.

The recreational cycling group said it "supports SAPOL'S use of discretion to enforce the law'' for all road users.

"Running red lights or using a mobile phone while driving or riding is an issue for all road users and these police figures are a wake up call for all,'' Bike SA chief executive officer Christian Haag said.

But he is also concerned at the increasing number of complaints Bike SA is receiving from its members about aggressive drivers.

"In extreme cases we have motorists hitting people and throwing beer cans or other items at them,'' he said.

But drivers who speed up to turn left and cut in front of a cyclist or fail to keep a safer distance from them are also being aggressive due to a lack of patience, Mr Hagg said.

As well as beliefs that bike riders regularly flout the law, Mr Haag said there was also a misconception that all "cyclists are Lycra clad riding in bunches and stopping at cafes for a coffee''.

"Some 40 per cent of sales are kids bikes, 50 per cent mountain bikes and only 10 per cent are road riding bikes,'' he said.

"Therefore only ten per cent of riders are Lycra clad roadies and 90 per cent are just regular riders like families on suburban roads.''

The RAA said it was "vital'' that road users obey the law and remove unpredictable behaviour which can lead to collisions.

The motoring organisation's road safety manger Charles Mountain also said high visibility was important among riders as it reduced their chance of being hit because drivers are unaware of their presence.

"That's why we also welcome the police attention on riders have the correct lighting on their bikes,'' he said.

According to the Motor Accident Commission cycling is an increasingly popular means of commuting.

"Unfortunately cycling related incidents continue to be a road safety concern. Since 2000 road crash casualties fell by nearly 30 per cent, whereas cyclist casualties increased by over 20 per cent," MAC spokesman Michael Cornish said.

"Cyclists account for approximately 7 per cent of Compulsory Third Party (CTP) insurance claims, costing the insurance fund approximately $26 million annually. In an effort to reduce "friction'' between motorists and cyclist and improve road safety MAC launched a website and campaign Be Safe Be Seen earlier this month.

SMILE, YOUR'RE ON CANDID CAMERA

CYCLIST David Angus didn't know what hit him when he was struck from behind while riding home from work along Anzac Highway from the city last week.

It was only when he heard yelling from a car as it drove away did he realise he was a victim of a suspected road rage.

News_Image_File: Cyclist David Angus at the place of the incident on Anzac Highway. Picture: DAVID CRONIN

"The attack was completely unprovoked - I'd been riding along minding my own business and felt this whack on my bottom and elbow and then yelling and an arm hanging out the passenger side window of a Commodore as it drove past,'' he said of the alleged assault on January 23 at 6.45pm near the Kurralta Park shopping centre.

"Luckily I kept my balance; if I'd fallen down I could've easily been run over by the car behind and I'd be dead.

Shaken but angry, Mr Angus, 37, caught up with the late model maroon Commodore at the tram boomgates on Marion Rd, Plympton.

He used his mobile phone to take pictures of the car's registration plate and of the front seat passenger.

News_Image_File: A car passenger hits David Angus's phone.

"The guy (passenger) started abusing me - telling me I shouldn't be on the road - then he slapped the phone out of my hand and it hit the ground, smashing the cover and damaging it,'' Mr Angus, a bank employee, said.

In his police report, provided to the Sunday Mail, Mr Angus said when he pulled up alongside the care he told the passenger "something along the lines of 'You are an idiot, you could have killed me'.

"He said something like: 'What are you going to do about it? Get your phone out of my face'".

He said the passenger hit the phone with such force it ended up 4m away from where he was standing.

Mr Angus has provided pictures of the car and the passenger to police.

- David Nankervis

CYCLING SPECIFIC ROAD RULES

HAND signals must be given when turning right

CYCLISTS may ride in an emergency stopping lane unless prohibited by a sign

CYCLISTS cannot ride more than two abreast unless overtaking.

WHEN riding two abreast riders should not be more than 1.5m apart.

CYCLISTS may ride in bicycle, tram, bus and transit lanes unless prohibited by a NO BICYCLES sign

CYCLISTS must ride in the bicycle lane unless it is impractical to do so

ONLY a rider of a bicycle who is under 12 years of age may ride on a footpath

THE rider of a bicycle must wear an approved bicycle helmet

AT night the bicycle must have a flashing or steady white light that is clearly visible for at least 200 metres from the front of the bicycle; and a flashing or steady red light that is clearly visible for at least 200 metres from the rear of the bicycle

CYCLISTS must not lead an animal while riding a bicycle either on a path or a road.

SOURCE: Australian Road Rules