I’ve (obviously) never ridden much but don’t really understand the handlebars that curve down. I looks uncomfortable, especially if you are breathing really hard.
I think it has to do with lessening your wind resistance…if you sit upright, your body will act as a sail, catch the wind, and slow you down/cause you to work harder.
It is more aerodynamic, comfortable and increases power.
The bars let you lower your body so your head, chest, and stomach block less wind, which means more speed.
Road bars allow you more control of the angle your back, and butt relative to your legs, which in turn can increase your power as well as your comfort.
Those are racing-style handlebars, originally from road-racing bikes, the ones with the skinny smooth low-friction tires. I think they were designed so that the rider leaned forward and lowered the “cross-sectional area” with which ey met the oncoming air, this reducing air friction and drag. Every little bit of reduction of air friction helped during a race.
Racing-style handlebars were the style in the seventies and early eighties, but real road-racers were a little… delicate… for the bumps and potholes of the urban street.
Meanwhile, off-road bicycles evolved through such sports as BMX, with big knobby grippy tires and straight handlebars that made it easy to turn the front wheel quickly when navigating gullies and trails and such.
Eventually, the two styles merged to form the “hybrid” bike, which proved to be ideal for city use. My bike has medium-size tires and straight handlebars.
Another benefit of drop handlebars is that it allows the rider to shift hand positions: either all the way down on the lower handles, halfway up riding on top of the brake hoods, or in the center flat part near the post. On a long ride, this is valuable, as it lets the rider stretch and use slightly different support muscles. The main point was aerodynamics and power, of course, but a lot of people prefer drops for the comfort.
I also know at least one rider who believes that mtb-style sideways handlebars were much worse for his wrists than drop handlebars (which are held with the wrists at 90 degrees from sideways bars).
To elaborate on one aspect of the increased comfort available with dropped handlebars, it lets you support a significant amount of your body weight through your shoulders. Sitting upright is nice for a while, but straight handlebars don’t offer much chance to get the weight off your butt. Tooling around town for a few miles it doesn’t make much difference, but going 40+ miles down the road with only one seating angle gets really old.
I think Quercus’ point is just as or even more relevant.
Ride a straight barred bike on a flat surface for an hour and you will be wishing for more hand positions. True trail biking requires a lot more hand and arm movement for balance, but locked in one or a few similar positions hands and wrists quickly fatigue. Ive ended up with pinched nerves and carpel tunnel like syndromes from road touring on a mountain bike.
Along with the trend from crosscountry to more downhill oriented MTBs has come a much more upright postion on MTBs that takes much of the weight off the hands and wrists (and gives better downhill stability). There is a whole category of ‘comfort’ styled MTBs that cater to casual ridrs with soft padded seats and upright riding positions.
The forward dropped position of road bars does reduce wind resistance but it also (feels to me at least) allows for better transmission of power to the wheels. I suspect it puts your center of gravity more in line with your legs and the drive wheel as well as setting your arms in such a positon to best use their strength. You can easily see this when you watch a road cyclist sprint, they use the lower postion and pump with their arms.
I much prefer the drop bars for road riding.
When I was 11, I got my first 10-speed and didn’t really use it right. My friends and I would go on ‘trail’ rides on trails that were not particularly well groomed. I bemoaned the fact that the skinny tires and handlebars that kept your hands too close together weren’t what I needed for riding these trails. What I wanted was a cross between a 10-speed (cause I needed to change gears on the rough trails) and a BMX with bigger wheels, you know, something a little more rugged but more appropriate for longer rides than a BMX. Alas, there was nothing like this in 1978 (that I could tell).
In high school we had a recreational bike club that would organize Sunday rides of 30-70km. At that time I had the 10-speed bike and the drop handlebars were perfect for being able to change positions and ride upright when having a comfortable tour and to be able to lean down when riding into the wind or on a downhill stretch. My prefered position is the top side of the bars just behind (or on) the brake boots.
I recently got a new mountain bike (like I envisioned when I was 12) and while it is good for riding the trails, it sure gets tiring on the road. I miss the different positions available to you with the drop bars. Going up a steep hill is especially different where I would be able to grab the lower portion of the bars while standing to pedal. I can’t get the right transfer of power when I try to stand up on the mountain bike because I’m standing too upright instead of slightly stooped. My hands also get tired of resting in the same position for any length of time. I’ll have to get a pair of the bullhorns to attach to the straight bar ends.
Hmmm…I wonder if anyone makes the drop bars a little wider, or maybe with the bottom part bent outward for a mountain bike…hmmmm.
Cantara-- there are indeed such things. I think what they call “randonneur bars” are frequently flared out a bit at the bottom and sort of angle outwards in the drops. A tad more comfy. I think lots of people use them in cyclocross. Nitto make a good one: see here