Eileen Harrington, 78, was left “badly shaken” after being swiped across the face by one of the men using a tool.
The incident took place outside the Civic Offices in Sir Nigel Gresley Square after Ms Harrington, founder of DonMentia – a Doncaster dementia charity - finished her “good deeds” for the day.
She said: “It shouldn’t happen to people like me, I’m one of life’s good guys.
“I was with another of the trustees doing good deeds, he went down to his car and I went to get my bike.
“There were two of them bending down at my bike, I knew it was mine because my hat, gloves and helmet fell out the basket.
“I confronted them and shouted at them to ask what they were doing with my bike and he just carried on cutting before pulling the bike free leaving me with the chain in my hand.”
Despite being around a foot shorter, the 78-year-old explained she was prepared to fight the man to get her bike back but fortunately, did not need to.
“I got hit over the head during it, I was swiped across my temple with his cutting tool,” she said.
“I think at that moment, I would’ve hit him with the chain, but for whatever reason he half attempted to ride away.
“He was nearly 6 feet tall and I’m 5 feet tall and an old lady and he just dropped it and moved onto the next bike.”
Ms Harrington, who said the robbers didn’t scare her, refuses to be put off by the incident and remains committed as ever to her charity work.
“I wasn’t scared, I was angry, I was mad – I have been burgled and broken into so many times I’m nearly blasé about it all.
“I’ve had to face up to people before, men in particular, who try to put me down and I won’t stand for it.
“It doesn’t make me worry about it happening again – I’m quite robust, I’m bold and brave.”
To learn more about DonMentia, visit: https://donmentia.org/