This is one of those topics where the question is too vague, hence the difference in answers. "Essential" is not defined and can be interpreted in a couple of ways:
- strictly: essential meaning absolutely required, fundamentally needed to enable the activity
- objectively: essential meaning personally believed to be important enough to be necessary due to specific benefits
- financially: essential meaning I am being paid to promote this.
Some of the responses here use the first definition - the only essential equipment for cycling is a functioning bicycle.
The correspondent in the OP appears to be using the second definition (with perhaps a whiff of the third...?) and since this is subjective it will generate differences of opinion and experience. So rather than me telling you what is essential, I'll outline my subjective reasoning and experience.
Well, for one thing it depends on what bicycle I am riding and for what reason. For my shopping bike I'll ride it in whatever I happen to be wearing that day; jeans, t-shirt, a coat if it's chilly, trainers etc. The only adjustments I'll make for riding are a helmet (most of the time), mostly because I believe in their ability to reduce the severity of head injuries and to set the example to my kids, and gloves if it's cold.
For cycling that is for fitness and leisure, I will specifically get dressed up for it:
- MTB:
- compression base layer - always, all weathers, short-sleeve or long (I have even been known to wear ONLY this in really hot weather)
- mid layers as required for the cold
- some sort of cycling jersey
- soft shell if required for the weather
- merino socks
- SPD shoes
- padded undershorts
- baggy shorts or trail trousers
- gloves - fingered or not dependent on weather
- heart rate monitor
- MTB helmet
- sunglasses if sunny; I have used clear glasses for non-sunny days but found they are more trouble than benefit in terms of getting mud spray and sweat on them
- Wahoo ELEMENT Bolt plus phone in jersey pocket
- tyre stuff, multitool and hydration bladder in small backpack
- offroad front light, generic rear (if dark)
- Road and gravel
- compression base layer - always
- mid layers as required for the cold
- some sort of cycling jersey
- soft shell if required for the weather
- merino socks
- SPD shoes
- padded bibs; short or long
- gloves - fingered or not dependent on weather
- heart rate monitor
- Road helmet
- sunglasses if sunny, clear if not (not for gravel usually)
- Wahoo ELEMENT Bolt plus phone in jersey pocket
- tyre stuff and multitool in bottle cage toolkit (road) or saddlebag (gravel)
- water bottle with water in it
- small front and rear lights
It appears to be a massive list and I always wear or use it, but none of it is "essential" (aside, arguably, from the lights at night). But it is all beneficial
to me either for comfort, performance or as insurance. I have never had a fall that involved contacting the ground with my head, and I don't want one either, but I am willing to carry the insurance with me for the unplanned time that it happens. My son took a relatively innocuous blow to the head a while back - no bleeding, no headache, no altered vision, nothing, not even a notable lump.... except he had total amnesia for around 20 minutes - didn't recognise me, his mother, his sister, his teachers (he was at school). That was very frightening, not least for him but also us. Thankfully he regained total recall within half an hour and has had no lasting effects
that we know of. Wearing a helmet is of little burden to me - being a little sweaty and having messed up hair are easy to cope with.
Sometimes articles like that come across to me more as self-important preaching and/or an excuse for air-time than as audience-focussed information giving. Click-bait, if you will.