Possible Clues:

• Bike stopper
• Worker on holiday, reportedly — one's pulled up at end of journey
• It may be used to stop a bicycle
• Pencilled letters are inclined to be slower
• Car immobiliser
• Parking assistant, worker needing holiday, it's said
• Manual device for holding car in static position
• It may be pulled
• It stops car worker taking a rest, say
• It needs to be released in a car race