Claims on stolen motor bikes have more than doubled this year, local insurance companies say.

Rocketing premiums mean insurance companies are now searching for ways to cut down on burgeoning claims.

"It has been the worst year on record,'' said Mr. William Madeiros, general manager of Colonial Insurance. "Bike theft is big business and a matter of great concern to us. We've certainly seen a substantial increase in bike claims this year.'' Crown Life Insurance assistant manager, Mr. Scott Kitson agreed.

"It's unbelievable -- claims have more than doubled. We've had clients who have lost three bikes already this year.'' Theft has become such a problem that the company is refusing to provide full insurance coverage to bike owners unless they hold other insurance policies with Crown Life.

And owners of bike brands most often targeted by thieves are told to go elsewhere if they want their vehicles covered for theft.

"We have stopped all cover for Yamaha V80 and V50 models because it seemed like every Yamaha on our books was stolen,'' said Mr. Kitson. "We tell our clients now that if they have one of these bikes they will get stolen sooner or later.'' He said the big rise in theft this year is because thieves are becoming more brazen.

But Bermuda Fire & Marine claims manager, Mr. Robert Jack said the company will continue to provide full coverage for all bikes, although some models are subject to higher premiums than others.

But in light of the recent rise in claims the company may soon be reviewing its policies.

"There is no question -- bike claims have more than doubled this year,'' he said yesterday.

Colonial Insurance began a "U'' marking campaign last month with the aim of cutting down on the incidence of bike theft.

"Premiums have gone up because of two things: bike theft is up and the value of cycles is up,'' Mr. Madeiros said yesterday. "Already this year the number of claims has surpassed that of August 1993 and there are still four months to go.'' But he said the "U'' marking campaign in co-operation with the Police cycle distributors would cut down on casual theft.

"We are trying to take a pro-active approach,'' he said.

Within the last month Colonial has hired an representative to "U'' mark bikes for Colonial customers at the place of purchase or at their homes for free.

And "U'' mark stickers have been redesigned with the approval of the Police to appeal to youngsters.

"We wanted them to be more of a fashion accessory that kids would want to put on their bikes,'' Mr. Madeiros said.

Colonial is also distributing posters promoting "U'' marking among schools.

But the company has no plans to refuse insurance for bikes popular with thieves. "Certain bikes are more attractive to thieves than others,'' Mr.

Madeiros admitted.

But he said distributors had also made an effort to educate their customers in theft prevention, in some cases handing out free kryptonite locks with new bikes.

"We don't like increasing premiums,'' he said. "We think people are fed up.

But this is a very definite cause and effect situation.'' Police records reveal the number of motor cycles stolen in the first seven months of this year has already reached the total number of bike thefts in 1993, making this year the worst on record.

Between January and September 1,346 cycles were stolen this year compared with 860 in 1993 and 679 in 1992 over the same period.