Halfords has said it plans to close up to 60 stores and garages by April.
The cycle and car repair chain plans to move as many staff as possible to other branches, but admitted the closures could result in hundreds of job losses.
“Covid-19 has materially changed the retail outlook for the coming months and has overshadowed Brexit as the emerging risk,” a statement from the company read.
Five Halfords stores and garages have been shut already, with the chain also closing its 22 Cycle Republic branches.
The company has 446 stores and 371 are garages currently. It employs about 10,000 people.
Halfords closed its stores at the start of lockdown, and has been gradually reopening since - first for collection-only services and then with social distancing measures.
Some 75 stores remain closed, but these branches are set to reopen in the coming weeks and are not necessarily the outlets that are tabled for closure by April, according to a spokesman.
The closures come as Halfords warned it could lose £10million if sales fell by 9.5% in the year ahead.
Under the best-case scenario, the company said its underlying profits would still fall £53million - despite a 57% rise in cycling-related sales during the coronavirus lockdown.
But that wasn't enough to make up for the drop off in car sales and services - with overall sales for the 13 weeks to 3 July down 2.8% on the same period a year before.
The chain is now looking to the reopening of MoT testing and the easing of lockdown to boost sales.
Chief executive Graham Stapleton said: "Having responded quickly and decisively to cater for the surge in popularity of cycling during lockdown, we are now seeing increased demand for motoring services and products as people start using their cars regularly again, having not done so for the last few months."
