A woman in her sixties sustained serious injuries on Monday afternoon.
A red MG ZS car and a cyclist crashed on the A4155 Reading Road, near to the junction of Mill Lane.
The cyclist was taken to hospital, where she remains in a critical condition.
Thames Valley Police is appealing for witnesses and says the 'serious injury' incident happened just after 2pm on Monday.
Investigating officer, PC Chris Weatherley, of the Roads Policing Unit, said: “I am appealing for any witnesses to this incident, during which a cyclist sustained serious injuries requiring hospital treatment.
“If anyone who was also in the area saw this incident taking place, or has any information, please come forward if you can help.
“I would also like to appeal directly to any motorists in the area who have a dash cam. Please review the footage and I would ask if anything significant was captured, please contact police.
Reports can be made by calling Thames Valley Police on 101, quoting reference 43200297138