Plans to ban bikes from trains during busy commuter periods could be opposed by Brighton and Hove City Council.
Rail firm Southern has said its rush hour services are so full of passengers there is no room for normal bikes at that time - only folded cycles.
But a councillor said the ban would undermine Brighton's aim to raise use of environmentally-friendly transport.
On Thursday the council will meet to discuss whether to ask Southern to reconsider its decision.
Southern operates trains in Sussex and Surrey, parts of Kent and services into London from those areas.
The firm's proposal would see only folding bikes allowed on trains travelling to London or Brighton between 0700-1000 and from London or Brighton between 1600-1900.
The restrictions are set to come in on 16 January and the firm has surveyed train users for their opinions.
Councillor Craig Turton has brought the motion asking the council's chief executive to write to Southern asking it to reconsider the move.