drop bars, wind resistance

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drop bars, wind resistance

Postby jawaka » Mon May 13, 2013 2:42 pm

I have done a search but this question must have been asked before. How much difference does going down on touring style drops make in %terms of reduced effort or higher speed?
If I had to come up with afigure i'd say 5%,6%, but I don't know whether feeling that you have got a weapon in your armoury against wind just makes me feel psychologically better when dropping down.
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Re: drop bars, wind resistance

Postby tatanab » Mon May 13, 2013 3:01 pm

What are "touring drops"? Talking about drops normally then the difference is roughly zero unless you lower your torso as well. For example, I ride with a fairly angled back and bent arms, going to the drops just straightens my arms and I'd have to make a definite effort to drop my shoulders.
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Re: drop bars, wind resistance

Postby RickH » Mon May 13, 2013 3:10 pm

This summary "Aerodynamics of Real-World Bicycles" of a wind tunnel study on bikes and riders in Bicycle Quarterly makes interesting reading including the following:-

A full aero tuck reduces the rider’s air resistance by 38% compared to riding “on the hoods.” There is nothing you can do to your bike that makes even nearly as much of a difference at high speed!

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Re: drop bars, wind resistance

Postby JohnW » Mon May 13, 2013 3:14 pm

Years ago, when both the world and myself were young, a friend and myself were freewheeling down a long pass from one dale to another. The roads were deserted apart from the two of us, and we were trying to see who could freewheel the better. We were both on the drops, and tucked down. I don't know what speed we were doing - there were no computers in those days. Both me and my saddlebag were the heavier, and I was pulling away from my friend. I sat up on the hoods, can't remember why, and in a second or two my friend came rolling down past me. He said that from where he was, the effect of me sitting up on the hoods (we called on the tops) was like putting my brakes on.

As for perecentages - I couldn't guess, but riding into the wind, it certainly makes a difference.
Last edited by JohnW on Mon May 13, 2013 3:52 pm, edited 1 time in total.
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Re: drop bars, wind resistance

Postby cycleruk » Mon May 13, 2013 3:49 pm

I don't know the actual difference but there is definitely one. :roll:
The latest tests show that being as low (horizontal torso) as possible but keeping the hands on the hoods is even better. More streamlined. :?:
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Re: drop bars, wind resistance

Postby JohnW » Mon May 13, 2013 3:54 pm

cycleruk wrote:...............The latest tests show that being as low (horizontal torso) as possible but keeping the hands on the hoods is even better. More streamlined. :?:


Yeah - from experience, I'd go along with that - and keep your elbows tucked in.
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Re: drop bars, wind resistance

Postby eileithyia » Mon May 13, 2013 6:17 pm

When my son was my tandem stoker, we were working into a head/sidewind it was coming on to front of our left shoulder... if that makes sense. Every so often I felt as though a brake had gone on the tandem, looking back my darling stoker was sitting upright not holding on and waving his hands around in the breeze, the difference between him sitting forward and further down with his hands on the bars was immense!

I too have out freewheeled heavier riders by staying in a tuck while they sat upright...
There's a reason why we all used to race on the drops as tucked as possible before TT bikes and tribars came along. You only have to watch a pro race to see how they use extreme tucks on descents to get as aero as possible.
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Re: drop bars, wind resistance

Postby NATURAL ANKLING » Mon May 13, 2013 8:25 pm

Hi,
I got this thing about going down hills while training............as fast as I humanly can :lol:
I normally go on drops where you can operate brakes, lower my forearms parralel with bars, grip saddle with thighs and lower bum so navel in on the saddle.
Prefer this to sitting on the crossbar.
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Re: drop bars, wind resistance

Postby Ayesha » Mon May 13, 2013 8:43 pm

You can get an idea of your Cd and kW/kmh by rolling down a hill and recording your maximum attained velocity for the gradient, Simple.

Repeat it for various riding positions.
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Re: drop bars, wind resistance

Postby MarkF » Mon May 13, 2013 8:55 pm

JohnW wrote:As for perecentages - I couldn't guess, but riding into the wind, it certainly makes a difference.


Yep, I have road bike with drops but prefer flats, I've always toured with flat bars. Last summer on my tour I spent day after day riding into an incredible headwind, that will be the last time I tour with flat bars, I still have nightmares..............
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Re: drop bars, wind resistance

Postby cycleruk » Mon May 13, 2013 9:55 pm

MarkF wrote:
JohnW wrote:As for perecentages - I couldn't guess, but riding into the wind, it certainly makes a difference.


Yep, I have road bike with drops but prefer flats, I've always toured with flat bars. Last summer on my tour I spent day after day riding into an incredible headwind, that will be the last time I tour with flat bars, I still have nightmares..............


There are a couple riders in our area who use flat bars with time trial aero bars for a "tuck" position.
I'm not sure they go any faster but it looks good. :mrgreen:

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http://www.ribblecycles.co.uk/sp/road-t ... rofhbat459
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Re: drop bars, wind resistance

Postby JohnW » Mon May 13, 2013 10:11 pm

cycleruk wrote:............There are a couple riders in our area who use flat bars with time trial aero bars for a "tuck" position.
I'm not sure they go any faster but it looks good. :mrgreen:

.


:lol: :lol: :lol: :lol:
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Re: drop bars, wind resistance

Postby LollyKat » Mon May 13, 2013 10:38 pm

Years ago I had quite a long commute into a regular headwind. After a week I had the handlebars changed from straight to drops. It was a 5-speed, 24-28 block - I found that going down on the drops I could ride at least one gear higher (same cadence) than when sitting up.

Coming home I sat up as tall as I could and sailed along merrily :lol: .
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Re: drop bars, wind resistance

Postby Mick F » Tue May 14, 2013 6:02 am

I've never noticed any real difference.
Yes, maybe a little faster on the drops and tucked in, but not much.

Maybe it's because I don't sit bolt upright even on the tops/hoods, no doubt if I did, I would notice the difference. It's all about the bike and the geometry and sitting comfortably and efficiently.
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Re: drop bars, wind resistance

Postby PT1029 » Tue May 14, 2013 7:29 am

Difference between on the hoods and drops I would say is minmal (my arms just swing down to the drops).
Difference between on the hoods and rops and being all tucked in, quite a lot.
Sitting bolt up right I find a good way to descend without having to put the brakes on.
Aero bars on flat bars. I remember seeing a 28 X 1 1/2" wheeled proper dutch town bike (mud guards, chain guard, rack etc) in the netherlands with quite highly set flat bars complete with aero bars for the head winds.
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