Geometry, flat bars and drops

[Twilkes]

I've read lots of stuff about how drops are more aerodynamic than flat bars (even though they're only generally 6 inches lower, not a huge distance, and I can crouch over my flats with my elbows tucked under my chest and not really feel much difference in air resistance). But then the relaxed vs aggressive geometry argument kicks in and I tend to get lost with the different bars and tubes that people talk about. So....

I'm probably moving from a Raleigh Pioneer with the bars about 5cm below saddle height (I'm 6ft5 so the saddle's pretty high), to a Revolution Cross where I guess the saddle will be the same height from the cranks as my Raleigh, and the bars could be set wherever I wanted them, maybe even 5cm below the saddle again. So what is it in the geometry of the frame that says I will encounter less air resistance? Surely if the saddle, crank and handlebars are in the same relative places, the frame has no bearing on anything?

Genuinely curious, as I'm happy on flat bars and was only considering drop bars to make headwinds easier to deal with.

 

[TheJDog]

Drop bars mean multiple positions, in the drops more aero, on he hoods, lots of control etc..

 

[sidevalve]

If the flat bars are in the same position as the drops then the effect would be much the same BUT then you wouldn't have the option of a higher position [bar tops] or forward position [hoods]. Further having the drops in line with the bike [ie front to rear] allows the wrists/arms to tuck in easier. Both racing AND touring riders have used drop bars for almost a century [I think] - they aint all wrong. Still there's no laws so each to his/her own, what ever suits you is fine [but I would give drops a try].

 

[Rob3rt]

6 inches lower is absolutelly huge.

Also, do you actually expect to perceive a difference in aerodynamics moment to moment? You won't... But if you measured the power to cover a set distance in a set time, you would realise how much energy is saved by being more aero!

 

[Twilkes]

If 6 inches is absolutely huge, then yes I'd expect to feel a difference in aerodynamics.

From my current cycling position, if I sit bolt upright I can feel the air resistance noticeably increase, so much so that I sometimes use it as 'air braking' when coming up to traffic lights. But if I'm cycling into a headwind and I crouch down over the handlebars I don't really notice any difference in speed for the same effort. It feels like the air is still getting 'stuck' in the bend between my hips and my chest, and the only way to remove this would be to get my head level with my waist, like in a TT position.

Maybe my current riding position is aero enough, as I already lowered my handlebars a fair bit from their factory setup, so the move to drops wouldn't be as significant as others have found it to be....

 

[Profpointy]

The "traditional" start point is to have the flat bit of the drops level with the saddle, thus the drop bit is indeed 6" or so lower. Mine are in inch or two lower still, and racers proper quite a bit lower probably. i'd be suprised if your flats are as low as the drop bit of drops.

 

[TheJDog]

it is probably easier on your arms and back to nearly lock out your arms on the drops, than to bend your elbows in to get the same effect on the flats. I read somewhere that the hands in the middle on the flat, elbows way bent position is more aero than being on the drops, but it is more tiring to be in that position, and there is far less control.

 

[Rob3rt]

If 6 inches is absolutely huge, then yes I'd expect to feel a difference in aerodynamics.

From my current cycling position, if I sit bolt upright I can feel the air resistance noticeably increase, so much so that I sometimes use it as 'air braking' when coming up to traffic lights. But if I'm cycling into a headwind and I crouch down over the handlebars I don't really notice any difference in speed for the same effort. It feels like the air is still getting 'stuck' in the bend between my hips and my chest, and the only way to remove this would be to get my head level with my waist, like in a TT position.

Maybe my current riding position is aero enough, as I already lowered my handlebars a fair bit from their factory setup, so the move to drops wouldn't be as significant as others have found it to be....

You are bound to be disappointed with such expectations.

I am also very doubtful that your air braking sensation is anything more than you thinking you should feel something, hearing the wind in your ears, and then "feeling" it, i.e. placebo.

Being more aero will save time, in the order of some number of seconds per mile (or power, i.e. some number of watts for a given speed), which adds up over distance however there will be no real time perceivable difference. You won't suddenly feel that cycling is effortless. On top of this, if you get more aero, IME you are not likely to ease up to maintain the seem speed as before either, you will keep pushing just as hard, but go a little faster, again, not perceptible in real time but adding up over several miles.

it is probably easier on your arms and back to nearly lock out your arms on the drops, than to bend your elbows in to get the same effect on the flats. I read somewhere that the hands in the middle on the flat, elbows way bent position is more aero than being on the drops, but it is more tiring to be in that position, and there is far less control.

Potentially it could be, it is narrower for sure and probably equally as "low" at the front, however with the short reach it would be quite cramped and the curvature of your back and indeed the highest point on your back being pushed up could make it less aero. Also, a narrow hand position could force the shoulders to round outward increasing the frontal area of the torso. The cramped position could also compromise power output, so even if more aero, it might be slower.

Another variation on this position, i.e. hands on hoods, forearms level, is just about as aero as being in the drops, better in some circumstances. I've read this in several places and also tested it myself using the virtual elevation method to deduce my CdA in both positions and it held true.

 

[Twilkes]

...hearing the wind in your ears...

Ha, spot on that this was one of my measures of aerodynamism. (come to think of it, my ears aren't particularly aerodynamic either)

I've done many 100 mile days on flat bars so hand positions aren't really an issue, was looking to make life a little easier on the legs. Will try a few drop bars again and if the riding position still doesn't click then I'll focus on getting a lighter flat bar bike.

 

[KneesUp]

I am (slowly) getting around to making a drop-bar bike out of an old hybrid. My starting point was going to be to get the flats at the same level as the flat bars that are currently on it, so that by extension the drop bit is lower.

 

[Twilkes]

Okay I tried a few dropbar bikes, and while I was only on them for a few minutes, the ride position felt like I was about to be launched into space, and the narrowness of the bars and the vertical hand position meant I was very uncomfortable doing low speed manoeuvres, even feeling very unbalanced just looking behind me for cars. So drop bars are a no for me.

I ended up buying a Kona Dew 2013 which was a bit of a bargain, almost the same spec as my previous Raleigh but 3-4kg lighter, and once I'd switched over to the 28mm tyres it was like night and day - I even counted the teeth on the cassette and crank (twice) because I thought the Kona must be a lower gearing, but no it's the same, and I can ride 48-15 in the same places where I would only be 38-15 on my Raleigh. This is probably just an indictment of how heavy and rusted the Raleigh was.

But the Kona did feel very upright, so I spent hours researching handlebars and ended up buying some Humpert Revoshift bars - fitted almost like reverse trekking/butterfly bars. I have a stretched out position where I can cover the brakes and rest my wrists on the flat bar, and a few side and upright holds if I need to change positions. There's room for some upturned bar ends next to the brakes if I need them, but otherwise this is a great set up that I recommend trying if you fancy a stretched out flat bar bike.

 

[Twilkes]

Someone else must have fancied trying it, because it got nicked from the side of the house on Sunday. 8-| Police are actually visiting this evening and mentioned checking local shop CCTV footage so that's a positive, although I'll believe it when I see it.

I'm fairly sure they'll switch the handlebars as they won't suit everyone and are very distinctive, but if anyone around Glasgow sees this bike around the west end/Knightswood then let me know. Ta.

 

[Indigo one]

I'd say 6 inches is huge but my girlfriend is less convinced as she has spent a lot of time around horses

 

[Banjo]

Someone else must have fancied trying it, because it got nicked from the side of the house on Sunday. 8-| Police are actually visiting this evening and mentioned checking local shop CCTV footage so that's a positive, although I'll believe it when I see it.

I'm fairly sure they'll switch the handlebars as they won't suit everyone and are very distinctive, but if anyone around Glasgow sees this bike around the west end/Knightswood then let me know. Ta.

Sorry to hear that .Hope the scrotes get caught or struck by lightning. Never seen bars quite like that , would certainly give you a wide range of hand positions. Good Luck