Cyclists have been advised to slow down and call out a greeting to horses and their riders, before them passing slowly with plenty of distance.
Charities Cycling UK and the British Horse Society (BHS) says this will make it less likely that horses will react and reduces the risk of injury.
The “Be nice, say hi” campaign follows an incident last June when a horse was startled by cyclists riding too close during the Windsor triathlon.
After a cyclist hit her, horse rider Jennifer Katherine wrote on Facebook that they “seemed to show no remorse”.
One of the cyclists smashed “along the side of my horse, taking my stirrup in the handlebars and bruising up my ankle”, she added.
The man also appeared to lift his “middle finger at me whilst riding off as I screamed”, she said.
Video of the incident ended up going viral.
At the time, the BHS warned incidents like this can lead to serious injury for riders and horses.
Cycling UK’s head of campaigns, Duncan Dollimore, has now said: “Every time a cyclist encounters a horse, there are three brains involved: the cyclist’s, the rider’s and the horse’s.
“Generally, if a cyclist startles a horse, it is due to simple lack of awareness that a horse needs more time to react, which is why Cycling UK is pleased to be helping the BHS promote the consideration and courtesy message of ‘Be nice, say hi’.”
BHS director of safety Alan Hiscox said: “Both groups are vulnerable road users and will benefit from working together to share the roads.
“Horses are flight animals and may react to anything they are unsure of.
“We are encouraging riders to respond positively to cyclists who pass with consideration, and reciprocate their courtesy.”