Random11

I see lots written about the aerodynamic features of bikes, but I'm wondering how much of a difference a more aerodynamic bike makes. Sure, if you're racing, you want every little advantage. But it seems to me (with no hard evidence to back this up) that most of the aerodynamic drag comes from the rider rather than the bike. What percentage of the drag comes from the rider rather than the bike? Any ideas? What if you had a bike with zero aerodynamic drag? How much would that reduce the total drag of bike and rider? If you went from the least aerodynamic road bike to the most aerodynamic, how much of a difference would that make in the total drag of bike + rider? You've probably seen, for example, bike manufactures advertise that lowering the seat stays makes their bike more aerodynamic. Would this really make your bike faster?

Mulberry20

The rider makes up between 70 - 80 % of the drag depending on who you believe.

I have two classic steel bikes, a Serotta Colorado and a Colnago Master, both I loved to death. Neither however are considered very aerodynamic.

Does it matter? Sure on the margin it does for pros but whether it matters to me is debatable.

After a fast 36 mile ride around Central Park in NYC yesterday I discovered something. It was hot and the loop was empty, so it was pretty fast with a few friends and some 25 year olds riding the latest and greatest.

My friend shows up with a brand new Trek Domane SL6 in total black, which I rode after we were done. That is a not a pure aero bike but has a lot of thing the Madone has.

I was so happy on that bike I did another 12 miles with the biggest grin.

So yesterday it mattered.....

Ferrouscious 

Aero doesn't exist.
Aero is everything.
Aero only matters in a race.
Aero is body position.
Velomobile.

bruce19

bruce19

Troul 

Depends on how the rider is dressed. They could be 100% drag, or just crossed slightly.

Cougrrcj

Rider must have the proper Aero position - including the Aerobelly! That's my feeling on this matter... as a borderline Clyde...

Random11

Thanks for the links to the videos. I hadn't seen them. Very interesting!

Homebrew01

Body position, helmet, shoes all make more difference. I prefer to focus on things I actually notice...components, clothing, shoes, saddle etc...
If I go for a ride and get home 15 seconds sooner, how would i know ?

If I were still racing, I might consider it.

AlgarveCycling

Aero bikes make only marginal gains whereas the rider accounts for the most drag, it's common sense. But those marginal gains are important to those racing against the clock where every second counts for them - unlike most cyclists who couldn't care less about a handful of seconds or even a few minutes, here or there.

On the flatter routes I do and for sprinting my aero bike is noticeably and measurably faster for me to use - same engine, me, as the constant, so yes, times can be measured against my non-aero bike to prove it. Of course, aero can only go so far and the steeper the gradient, the less the time saving. My much lighter 'climbing' bike is night and day faster than my heavier aero bike on steeper gradients - that's not just how it feels, I have seen the time differences across the segments on Strava for the same watt efforts.

So sure, the rider makes up the vast majority of the drag which accounts for why rider weight, shape and body position is so very important along with technique, the ability to spin and power. The bike, however, does contribute and can make a difference to those racers - and you do not need to be a Pro to realise them - who want every advantage. Obviously too, a rider who is appreciably stronger, quicker, than another will still be faster overall even if riding a much heavier, less aero machine. The proof of difference a bike makes must be calculated by the same engine - rider - on different bikes at the same watt power over the same course in the same conditions to ascertain those time differences. Being in the top 5 in my region/state for my age category, I'm fast on my 29er XC MTB and can beat most regular Club-level road cyclists in my area on it but that's because I am the stronger cyclist and can beat them riding , what is essentially, a brick with wheels. That doesn't make my MTB the equal of my aero road bike. I'm far faster on my aero road bike.

canklecat

It all adds up.

I have a couple of sets of aero bars, and an older entry level TT/tri bike with a minor crack in the seat tube that I went ahead and test rode anyway. I can't hold an aero tuck for more than a minute at a time due to an old neck injury (my C1-C2 were permanently damaged in a car wreck 20 years ago, and reinjured when I was hit by a car in 2018).

But even with holding an aero tuck for only a minute at a time, sitting up to stretch my neck, and tucking again, I could improve my speed by a full 1 mph over my usual 10 and 20 mile loops. That's huge, considering my bike fit was mediocre at best and my form was terrible.

A local woman close to my age (I'm 62) who occasionally rides with us on spirited group rides tends to fall back when she's on her standard road bike, but when she's on her tri-bike she can smoke my best times on most segments, other than climbs. That's how much difference aero bars and good form can make.

It was enough to persuade me to try some tricks on my standard road bike setups with ordinary drops. So I got some very snug form fitting jerseys, an aero helmet, and can improve my average speed by at least 1/2 mph on the usual 10-30 mile routes. Some minor tweaks to my bike fit -- stem length, bar height, compact drops, saddle position, etc. -- helped me to hold the position longer with my forearms parallel with the ground. And this was with older non-aero road bikes -- my '89 steel bike, and '93 Trek 5900.

And that's with way too much crap on my bikes. I run front and rear video cameras every ride (the one time in three years I didn't was the day I was hit by a car -- the case is still dragging on more than two years later). And I pack a fairly full saddle bag -- at least one tube, multi-tool, CO2 kit and mini-pump, etc., because I don't want to call Uber or a friend for a ride. And in summer I always carry at least two 24 oz bottles. If I stuck with a 5 mile loop near home I could skip most of that junk and possibly gain a little time/speed.

Don't have aero bars, or don't want to bother with them? (They're awful in crosswinds, which is why I took 'em off my road bike.) Check out Remco Evenepoel in January's Vuelta a San Juan stage 3 time trial. That race omitted dedicated time trial bikes so that teams with lower budgets could compete equally. So everyone used their standard road bikes. Some riders used the "invisible aero bars" or puppy-paws position, forearms or wrists draped across the center of the bar to get the forearms parallel with the ground, heads low and backs as level as possible. But nobody did it better than Evenepoel, who blitzed the field. The attached video shows only the highlights. GCN has the full race with longer clips of Evenepoel demonstrating his excellent form on a standard road bike. Sure, the skinsuit and aero helmet helped a bit. But it was mostly engine and good aerodynamic form on the bike.

BlazingPedals

Aero gains are cumulative. You don't have to be a racer to appreciate them. Guess which cyclist is working the least - the guys drafting or me up front on the recumbent?

walnutz

Guys, I’m running out of popcorn over here!

Kapusta

I never though much about aero.

Then one day I tried closing my ubrella for part of the ride and it made a difference.

ofajen

Here is an article where a lot of aero options are evaluated for impact on wind resistance. Lots of detail and some references.

https://www.sheldonbrown.com/rinard/...odynamics.html

Otto

bruce19

Or just bi-cyclists.

AlgarveCycling

Some recumbents are definitely very aero and efficient in many respects if that style of riding is your thing - and certainly, on smooth flat terrain you can get away with fewer watts per mile from what I am told by owners.

Perhaps not ideal where I live given that the few I see get utterly annihilated and can't keep up at all since the hills are too many and too steep generally and that includes a former Pro who rides one on and off. He's a Frenchman in his mid-50's. One day I'll see him on a time trial bike with a solid disc at the back, head down and going for it, the next on a tandem with his wife, another on his general road bike, on his MTB that he races and sometimes, I'll catch him riding his recumbent that he brought here with him from France. He has offered to let me have a go on the bike but I've yet to take him up on it. By his own admission, we live in an area perhaps not best suited for it. He reckons he can hold a good pace on the right road but it's hard work on our lumpy terrain where e-bikes are becoming very popular now.

Edited to add: Different bikes for different disciplines, while some can crossover to perform over any type of terrain, bikes specifically designed for a particular best use are obviously better at that - MTB's are ultimately better on rocky, technical terrain over gravel and road bikes, time trial machines faster than GC, cyclocross better than GC for their intended discipline, GC road bikes better than gravel on smooth roads, recumbents too have their particular niche etc etc. In terms of aero, the more aero we can achieve with each, the quicker we will be. Of course, marginal gains so how important those are varies from person to person and their goals.

BlazingPedals

So, we're talking about aero. Why do you feel the need to bad-mouth recumbents for hill-climbing - mountain climbing, really - when that's not the subject of the thread? As you can see in my pic, there are no mountains where I ride; so your rant has no application.

AlgarveCycling

Wow! Someone's over-sensitive!

I'm not 'bad-mouthing' anything, I'm sharing in the context of aero and different bikes. Rant? Jeez, you need to grow up, matey, and get that chip removed from your shoulder if you seriously think I was having a rant or even a go at one particular form of bicycle. There are many types, we choose what we like. If I mentioned that a Penny Farthing would be less aero would you take as much offense? Just because you ride recumbents doesn't mean you should be so sensitive and feel the need to 'defend' them as a choice if someone states they find another form of bicycle is perhaps more appropriate for a type of terrain. Should MTB'er's get all wound up and triggered as you just have if a Gravel bike is faster on a particular off-road segment or should they be mature enough to realise that, yes, gravel bikes being more aero will be the faster choice on less technical off-road sections, albeit ultimately, slower if the terrain is very technical?

BTW, read my post, I was specifically referring to where I live, not you. It isn't all about you, Mr Fragile & Sensitive. If where you live it makes sense to you, great, go for it.

caloso

Time saved over a 40km ITT. Helmet and clothing are the biggest factors not attached to the bike.

burnthesheep

Maybe nobody asked you? Rant? Bad mouth? Not to be mean, just saying to lower your expectations a bit for what you'll encounter when you bring something like that up.

Nobody said "get out of here recumbent boy" like the pizza boy showing up to the street race in Fast and the Furious. But that's always the victim hood mentality when the e-bikes and recumbents get replies to topics in the other forums.

His response might have been off target, but not offensive. Grow some skin.

You're welcome to bring in the bents, but don't get bent out of shape each time they get challenged.

HTupolev

I know a couple guys with Bacchetta high-racers who don't have tons of trouble on hills. The recumbents are somewhat heavier than their road bikes, so they do lose a bit on a consistent steep gradient, but if a hill is really shallow or has dips on the way up, they can achieve comparable or in some cases even better performance on the 'bents than on their road bikes.

As long as the recumbent isn't seriously compromising a rider's power, there's no obvious reason that it would climb especially badly. From what I've seen with my friends' power data, peak sprint wattage is lower on the recumbent, but for longer intervals they can sustain pretty comparable results.
Obviously you can't throw your weight around on a 'bent, and have to sit and spin everything out. So my friends do use wide-range triples to facilitate slightly lower bottom gears than on their road bikes, while also providing the extreme top-end that they want for the fast descents.

I think a major factor behind the idea that recumbents are disastrous on hills is that people don't realize how large the aerodynamic benefits are. If someone on a fast recumbent is putting in effort to hang with a road paceline on the flats, they're far weaker than the people on road bikes in that line. If you don't realize how much weaker they are, then when the road turns uphill and they blow off the back like they're going backwards, it's easy to blame it mostly on the bike when it's likely mostly the rider.

asgelle

I think it's time we retired that figure. Aside from the problems with the data which were well covered at the time (not least of which failure to account for the extreme variability in clothing performance based on physiology), technology has advanced so much since then that the numbers really aren't relevant anymore.

caloso

Whatever the numbers, the point remains that the biggest aerodynamic factors are the rider's head, clothing, and positioning.

fietsbob

Pros in the Big Tours like TdF, Vuelta & Giro have individual time trial days..

Do you have any individual time trials you compete in, for this to matter?