Thanks 
. Great to see real life numbers. Doesn’t seem like such a big difference to me!
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What are your body and bike weights?
That was a brilliant video, thanks for sharing! 0.5km/hour difference once the tires were swapped seems negligible. Just need to train a teeny bit harder 
72kg body, 10kg bike (saddle bag, bottles etc).
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You should try running lower pressures. Silca’s tire pressure calculator suggests 52 psi in the rear and 56 psi in the front. (Your rear pressure is lower than the front since you run a wider tire in the rear.)
With SRAM’s tire pressure calculator you should get 49 psi (front) and 48 psi (rear) if I select wet and 55 psi and 54 psi in the dry.
Note that both have a few options. I opted for bad pavement for Silca’s calculator and the recreational rider setting.
I’d treat these values as starting points and experiment a little, changing the pressure by 2–4 psi at a time. Even though the changes in pressure are small, in my experience the impact is immediately felt as you move the resonant frequencies around. Those depend on the tarmac and your speed. If set right, the buzz is soaked up by the tires.
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Horizontal. 
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If you are riding in a group, I’m not sure aerodynamics are as much of a a factor as long as you are not getting dropped 
. It’s just a bit of a flex on the others, lol
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A couple km per hour is a lot if you are trying to be fast. When the bunch is hauling bootay, you’ll really feel the lack of aero especially if you have to take a pull or want to attack.
In the end it just depends on what you want to do.
For me the killer with using my gravel bike on the road is gearing. I don’t have enough for fast motoring and I don’t like the large jumps in the cassette.
I upped my aero game about 5 years ago. I was 53 and had started group riding again with the youngsters. I did:
50mm aero wheels
GP5000s tubeless (from GP4000s)
aero / race fit jersey
aero helmet - Ballista
I thought that was reasonable for the money and the gains. Going by various calculators, the watts add up - 20 watts for wheels, 10 watts for fast tires, 20 watts for fast kit and bike positioning, 5 watts for a helmet.
I can say it made a large difference. I ended up with 3 pages of Strava KOMs after those changes. Going down a mountain, I’d just coast away from friends without good aero gear.
If your group ride though is mostly sitting in the wheels, taking an occasional pull, and then stopping for a pastry after an hour or two, then you certainly don’t need aero.
Crazy that you can essentially buy 35 watts!
This. I switched from a TCR Advanced Pro 1 to the top spec Cdale System Six and the difference is crazy on flat roads… my average speed is around 1 mph faster on zone 2 rides.
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Dollar per watt, I would say look at an aero cockpit. Something ~36cm at the base of the hoods, and possibly turn the hoods in a few degrees. Make sure the bar has a wide flat top to rest your wrists that is also extremely helpful to spread out the weight and unload the stress on your wrists, which releases muscle tension in your arms and hands. Work on building a comfortable “all day” position on the hoods that puts your head and shoulders as low as possible and your forearms as flat as possible, with elbows that aren’t too far outside your knees. Out of all of the upgrade options out there, the cockpit to me is the most underrated upgrades you can make. I upgraded my wheels & tires on my tcr but honestly didn’t think it made all that much of a difference, the biggest change was upgrading bars and really focusing on maximizing time spent at minimum CdA.
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This is a good post, but do bear in mind that watt savings depend on speed. Tour magazine does testing at 45kph. Their testing also includes wheels. Sometimes they normalize with zip404s (I think), sometimes not. Giant tcr testing was done with shallow wheelset, while all aero bikes are with deep wheels. Some of them are also sending bikes with extra narrow handlebars, I think van rysel did it recently with 36cm.
The increase in watts required vs speed is not linear. If your bike has 40w difference at 45kmh (could be quite likely), it will be maybe 7 watts at 30kmh.
The savings/loses then depend on the speeds you are riding with your group.
The numbers are even worse if the rider is the type that shows up with a flappy wind jacket and they have something like Gatorskin tires installed. Those two items alone are probably like a 30 watt penalty.
If you are this guy and you do all the aero tweaks, you gain 60 watts.
You really can’t….the numbers aren’t cumulative. Everything affects the systems to varying degrees.
Yes, you can absolutely buy watts, and the difference can be significant, but adding them together like that is not realistic.
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A little bit “off-topic”, but not that much. (sorry OP)
First, I want to disclose that I’m not against aero/watt savings. Buy the best you think fits in your pocket, I’d do the same (if I have deep pockets hehe).
Disclosure made, and as mentioned, most tests are conducted at 40km/h. And my genuine question is, how much time do you spend riding alone at 40km/h or more?
If you live in a slightly hilly place, not as much as you may think. So, despite all the marketing campaigns about watt savings, is it really the holy grail?
What is more important, a 7.2 kg bike not as aerodynamic, or an 8.5kg aerodynamic one? If you ride in groups, and there are a handful of 3 to 5-minute hills throughout a 60/70km ride, I’d confidently say that the lighter bike. I know that now you can almost have both worlds together, but the cost of the toy increases exponentially while you can get an under 2k USD used rim brake bike weighing 7.4kg that will perform just as well in those conditions.
My riding characteristics and riding buddies might be different, but we rarely have group splits in the flat. But when climbing even shorter ones, that’s where the kid cries and mom doesn’t see.
TLDR; companies are making those claims about watt savings to mask the truth that disc brake bikes are heavier. To get a proper lightweight disc brake bike the cost is absurd.
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Every study of this that I’ve read shows that aero savings trumps weight savings except when it gets really steep (like > 9% grade).
For group rides and races, it’s the selection points that matter. It doesn’t matter that you might sit in the wheels 90% of the time. Now one has to decide whether they want to be at the pointy end of things or not.
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Also keep in mind that if your doing 20kph of ground speed into a 20 kph headwind, your doing 40 kph airspeed. So there are lots of times where I’m riding solo at 40 or greater airspeed and those aero drag numbers are applicable.
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@AJS914 would point me to some of those studies? I’m not doubting you, just curious to see how they calculate this. I really can’t see going uphill at 16km/h 8% can be better in aero 8.5kg bike than a light 7.4kg non-aero.
@DavidYYC Sure, headwind is a hell to ride.
Just to be clear, VERY CLEAR! I’m not arguing against aero gains, I’m saying that there are a few situations, which will depend on your specificity, that they might be overrated.
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Has to depend on your power to weight ratio. For an elite rider perhaps aero trumps weight at grades <9%. I just looked at my A event for the longest climb. It was 1500 ft with an average gradient of 8.4%. My average speed was 6.9 mph. At that speed, lightweight was the way to go. The fastest person in my age group was 7.9 mph. Doubtful aero would have trumped weight for him either.
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This is purely a mathematical calculation. I was playing with the Analytical Cycling website like 10 or 15 years ago. That site is dead, I believe but there are many other calculators out there:
If you want to read an article:
If we take a case study for an amateur rider: a 75kg rider, 7.5kg bike, 7% gradient climb, 15km/h road speed. Climbing at this speed and slope would require ~275 W. An amount sustainable for a fit amateur rider of this size (3.7 W/kg). The addition of the 1kg dead weight would add only 3W resistance under these conditions. This is not nothing, but it is just a little over a 1% increase in resistance.
Plus, the lightweight vs. aero debate is not even a debate. One can build something like a Tarmac SL7/SL8 at the 6.8kg weight limit or even less these days … pretty easily in fact.
Even if aero equipment were heavier, a 20 watts savings on wheels dwarfs a 3 watt loss for +1kg. A 15 watt savings with a traditional “aero” frame dwarfs the extra weight.
Per the article, the balance point is a 6% grade. If you look at the graph at 9 or 10%, the weight penalty is still pretty small.
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