The Motor Trade Association (MTA) survey, which observed almost 350 riders in Wellington over the first half of the month, found 51 per cent of riders were on the road without ACC-recommended safety items such as gloves, trousers or jackets.
Ms Lack said riders needed to invest in proper safety gear.
Those who flouted the recommended safety practices would be seriously hurt if they came off their bikes, she warned.
"You're going to lose a lot of skin and probably break bones ... whether you're at fault or not."
MTA spokesman Hamish Stuart said the survey results, which found gloves were the most commonly omitted piece of safety gear, were alarming.
"If someone is falling off their motorcycle, it's a natural human response for them to put their hand out to protect themselves. Having proper gloves is a pretty cheap way to prevent more serious injury," he said.
A lack of appropriate leg and arm protection was the second most common breach identified.
"Bare skin and tarmac don't mix well," he warned.
"Skin comes off easily, and even if it's a slow speed accident, the outcome can be plenty of pain, loss of earnings and in some cases even the motorcycle itself."
The Transport Agency estimates the social cost for a serious road injury is $401,100. This increases to about $3.8 million for a death. Minor injuries have a social cost of $21,300.
Lost earnings, medical fees and vehicle damage costs are included in the estimated social cost.
Of the 45 motorcyclists deaths last year, one occurred in Rotorua.
Mr Stuart urged riders to be extra careful on the roads.
"Bikers and scooters can be a convenient and cheap way to travel but they definitely need plenty of situational awareness, given the rider is so much more exposed."
Dangerous riders:
338 motorbikes and scooter riders were observed in the Motor Trade Association survey carried out in Wellington between 7.30am and 6pm over the first fortnight in March
171 were classed as "shocker" riders because they were missing at least one piece of essential safety gear, such as an adequate helmet or gloves
167 were given a safety-gear rating of "pretty good" or above
Source: Motor Trade Association