Halfords' retail cycling sales fell by 0.3 per cent like-for-like, in a report that covers the 14-week period to 4th January.
The retailer said growth in cycle accessories and children's cycling was offset by a decline in the more discretionary and bigger-ticket adult bikes.
Group revenue fell by 1.7 per cent like-for-like, with a 1.4 per cent growth in Autocentres offset by a 2.2 per cent decline like-for-like in retail.
Graham Stapleton, chief executive officer, said: "This has been a challenging third quarter for the business, driven by exceptionally mild weather and ongoing weak consumer confidence.
“Together, these factors have led us to reduce our profit expectations. Whilst this has been a difficult period, we have managed costs and margin well and our free cash flow remains strong.
“Halfords is a robust business and we firmly believe that the strategy we outlined in September is the right direction for the business."
Earlier this month, it was reported that Halfords will sell the Cybic bike range from summer 2019, the 'world's first' connected smart bike with access to Amazon Alexa.