Lord Lucius Falkland, chairman of the Motorcycle Industry Theft Action Group, switched his insurance from NU, the market leader, to Devitts because of the high premiums it was quoting for his Moto Guzzi California.
He said: 'Norwich Union was quoting rates without any consideration for the type of bike.'
NU's new Premier Bike policy has 17 different cc bands instead of seven. It also offers discounts for people who take extra security measures and for existing NU policy holders.
About 400,000 motorcyclists are insured with the company - two-thirds of the market.
Under the old Rider policy a 30-year-old man in Cambridge with a clean licence, with a bike of 225cc or under, would pay pounds 173.
Under the new Premier Bike policy a Honda CG125 rider would pay pounds 145, a Suzuki GS125 rider pounds 190, and a Yamaha RD200 owner would pay pounds 210.
Lord Falkland said: 'I had my bike under the Rider policy. It was ludicrous.'
Lord Falkland is one of an increasing number of members of the House of Lords who travel to the house by motorbike. He is also a founder of the 44-strong all-party motorcycle group, which comprises 29 MPs and 14 MEPs who use motorbikes on a regular basis.
He said he had lobbied the motorcycle insurers to streamline the rates through his chairmanship of an action group to combat motorcycle theft.
He pointed out that the insurance industry had very few statistics on the accident rates suffered by different types of motorcyclists and the variations in the risk of theft among the different brands of motorcycle.
For example, Lord Falkland said that Japanese race replicas and Harley-Davidsons were among those that were the most stolen.
He added: 'Accidents on Moto Guzzis are few and far between. People with this type of bike are less likely to race around.'
He said that the whole motorcycle insurance industry was in a crisis a few years ago because the insurers had not moved with the times in the structure of the insurance policies.
About 10 companies offer motorcycle insurance. Rates can vary by up to 100 per cent in some cases. Premiums are charged on the bike's group rating, the age of the owner and the district where the bike is kept.
The second-biggest insurer in the market is Devitt Insurance Services. Others offering motorbike insurance include National Insurance Skandia, General Accident, London & Edinburgh, Cornhill, Eagle Star, Lombard Continental, Landmark Insurance and Lloyd's.
David Moore, sales and marketing manager of Bennetts Insurance Brokers, said that the motorcycle insurance industry had gone through a turbulent few years.
He said that rates had gone up by more than 200 per cent over the past few years because of the vast increase in the rate of theft and the rise in personal injury claims.
The situation culminated with many insurers pulling out of the market, leaving those that were left nervous about taking on the increased business.
Norwich Union, for instance, stopped offering bike riders under 28-years-old fully comprehensive insurance.
Mr Moore welcomes NU's bid to streamline the rates but adds: 'Norwich Union does not allow a no-claims bonus. In reality, a 30-year-old would almost certainly be entitled to a no-claims bonus and virtually all other insurers apart from Norwich Union will allow a discount of up to 40 per cent.'
He said that a Kawasaki ZZR1100 rider with a four-year no-claims bonus would get a reduced quote from Lombard Continental of pounds 520.
(Photograph and table omitted)