With the size of cycling sunglasses on a constant upwards trajectory towards comedy value, there's little chance of any of us getting close to those figurative windows to the soul.
The next best inlet, then, is perhaps the humble jersey pocket. Unless of course the contents have been deported to the newly created bib short pocket, or a frame bag - but then that's a clue in itself.
Here's how to determine a rider's objective on the bike, with a glance at the size of their jersey pockets...
Crit racer
(Image credit: chris catchpole)
Nothing.
This rider intends to spend the next 30-60 minutes pummelling themselves at a speed and intensity which leaves zero room for contemplating anything as attention consuming as the on-boarding of energy.
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Despite being charged ~£20 for the pleasure, British Cycling's infinite wisdom dictates that laps out aren't allowed so there's no point carrying any sort of mechanical magic fixes.
Road racer
Several gels, a pre-opened energy bar, and possibly some sort of puncture fix if the circuit is really long and neutral service is likely to be as forthcoming as a chubby handed toddler with the keys to the sweet cupboard.
Time triallist
Image: Andy Jones
This depends if we're talking old-school time triallist, or the new breed wearing a helmet that wouldn't look out of place in the stingray tank at your local aquarium.
But the 'trackie trolley' (carried via the lift to the velodrome pits) contains a chainring and rear cog in every size available, spare handlebars and a pair of compression socks that might even raise eyebrows at a triathlon.
Sportive rider (see also: club runner)
It's about now that things take a dramatic turn towards the more laden end of the spectrum. The sportive rider inhabits a sweetspot between the minimalistic nature of racers and those who require a frame bag - the result is usually marked out by low hanging pockets.
Food is an obvious one, plus a spare tube, tyre levels, Co2/canister, a pump in case of disaster, quick link, multitool, rain cape, and half a bag of Haribo (the other half served as a great post-breakfast-chaser).
The well prepared types also allow space for a tyre boot and latex gloves.
Gravel rider
Image: Jake Stangel
(Image credit: Jake Stangel)
This rider intends to leave no 'groad' unexplored - and as a result carries enough supplies for a full day out, possibly the night as well, with extra tools required to cater for the fact that no 'rescue taxi' driver will take kindly to receiving co-ordinates for a flint strewn path 50 miles from precisely nowhere.
Additions include spoke keys, cable ties, lights, portable chargers (if you didn't take a photo for Instagram, did it even happen?), plus a metal mug that can be clipped to the luggage - where it will clang with every pedal stroke.
All of the above - plus bivvy bag (or, a down jacket which forms a part of a sleeping bag...), spare clothes, mini stove, Swiss army knife (self defence only), AeroPress, and an assortment of photography related paraphernalia.
