So one of the biggest, easy gains that you can make is by jumping on the aero base layer band wagon if you havenāt already. Some people/brands call them āaero brasā as they are like crop tops for dudes and women can wear them too (over their sports bras of course - these are definitely not a replacement for normal bras).
I have a couple of links here below. The first one is the rule 28 which is one of the better tested aero base layers on the market. See Nero Show Episode 155 on YouTube (the first 10 mins of the show breaks down the results) to see the data on this. The second link is an aliexpress one which Iāve bought before and I wouldnāt think itās far off in terms of aero savings.
These things definitely help save time. But you need to be hitting 40kph regularly in order for it to be worthwhile. Usually the faster you go the more of a difference the aero equipment will make - but on the Nero show they found the aero bra to be equally effective at both 40 and 60 kph in terms of watts savings (cannot remember what it was but it was the same amount of watts saves at both speeds) which is pretty unusual. As a percentage that means itās more useful at 40kph but still definitely worthwhile (so not equally effective as I said in the last sentence š¤ but still very useful!). Especially during long distance events where you could save tonnes of time for zero effort.
Itās probably the most cost effective upgrade you can buy. Way faster than buying a new bike unless you are riding a gate, but for most people it would make a more significant difference to get one of these things.
2 situations where they arenāt worthwhile:
If its really hot then you are best not to wear an additional layer despite how light this thing is. If heat could be an issue in any way then I would ditch this and focus all your energy into heat protocols like ice, slushies etc. and donāt bother with the extra layer of kit.
If itās so cold that you are wearing jackets and that then you wonāt be receiving any aero benefits from the aero base layer(shockingly š). The grooves of the aero base layer sleeves need to protrude under your jersey sleeves to obtain the aero benefits ( I donāt really know how to articulate that point but have a google if youāre confused and itāll make sense). So if youāve got too many layers on then you will not be availing of these gains. Prioritise staying warm though in this case of course. Everybody else will be cold too so itās not like you are missing out on something compared to everybody else.