Cycling and motoring products retailer Halfords has been left nursing a fall in half-year profits after seeing bike sales slump.

Halfords also warned that earnings in the next financial year were also unlikely to grow, but recently hired boss Jill McDonald put faith in a new turnaround plan to get its performance back on track.

This includes a renewed push in the bike sector, with Olympic and Tour de France champion Sir Bradley Wiggins signed up to launch a new children’s range. He will help design eight bikes as part of his campaign to get more children into cycling, with the range due to hit stores next July.

Ms McDonald unveiled her overhaul after a “disappointing” summer for bike sales, which fell 7.6% on a like-for-like basis in the group’s second quarter, down by 11% between mid-July and mid-August.

Sales were hit by poor weather and high promotional activity, with the decline compounded by tough comparisons from a year earlier.

The result was a particular blow for the group, coming in its peak bike selling season, and contributed to an overall 5.9% fall in underlying pre-tax profits to £46.4million for the six months to October 2.

Halfords said annual profits in its new financial year would be “broadly unchanged” on the current year, but said it expected growth for following years.

Ms McDonald, the former UK head of fast food giant McDonald’s, who replaced Matt Davies at Halfords in May, said: “Halfords is now a fundamentally strong business, operating in markets with good growth prospects.

“However the modernisation process is not yet complete. Under the new strategy we will continue to invest to move from fixing the basics to enabling sustainable growth.”