One in eight (12%) home contents insurance policies provide no cover for pedal bikes as standard, according to analysis.
Many of them will have cover available as an optional extra, for which customers would need to pay a higher premium.
And for policies that do cover bicycles, the payout limits can be low, financial information and star ratings service Defaqto said.
Of those that include cover, a fifth (20%) of those analysed offer less than £1,000 and 5% offer less than £500.
Cyclists should also check with their insurer to make sure their bikes are covered away from home.
Only 16% of policies will provide bike cover away from home as standard while others make cover optional in some way.
Many people have turned to bikes as a way to exercise during the coronavirus lockdowns.
But Defaqto said people making a claim if their bike is stolen may find that the amount of cover would not be enough to buy a like-for-like replacement.
Brian Brown, consumer finance expert at Defaqto, said: “Thousands of bikes are stolen every year and unfortunately you may find that your insurance does not provide enough cover for a replacement now.
“It is worth checking what cover you have and speaking to your insurer if you need to change this. You may also want to consider a specialist bike insurance policy if you have one of the more expensive models.”