Aerodynamics is the key, not wheels

[mikesbytes]

Having read this article about wheels, I can see that weight and aero of wheels is way down the order and the most important thing is wind drag on the body. All the details are in the article and here's a simplification;

% improvement
26.0% Rider drag
9.7% Rolling resistance
3.7% Frame drag
1.8% Rider weight (4.5kg of Body Mass)
1.8% Front wheel drag
0.6% Rear wheel drag
0.19% Lighter rear wheel
0.14% Lighter front wheel
0.020% Rear wheel inertia
0.015% Front wheel inertia

It seems that lowering my handlebars is the best performance improvement I can make, then get good tyres, tubes and then get an aerodynamic frame. When I do get new wheels, make sure that the front one is an aero one.

BTW, has anyone got access to a wind tunnel ?

[weiyun]

I think the issue there is, apart from your body position, you can't really reduce the rolling resistance and other factors by as much as you can with a more aero wheel. So apart from the body position and cloth gears, aero wheel is the one to give you the biggest bang.

[mikesbytes]

According to those stats, the frame drag is more important that the wheel drag

[weiyun]

True, but to reduce the drag coefficient on the frame is that much harder than the wheel.

[T-Bone]

Just remember, lowering your handlebars may not be comfortable on longer rides, and may reduce your power output, in which case, although you require less power to go the same speed, you are producing less power, which defeats the purpose. It's always a compromise.

I'd say good tyres are probably the easiest to improve. I have some nice veloflex paves on my race wheels, with latex tubes. I don't worry too much about training gear, though i always buy good tyres, just trying to get through my supply, and then i'll probably just ride on GP4000S all the time, or maybe Schwalbe Ultremos.

As weiyun has said, since these percentages are for 50% reductions, it's very hard to reduce frame drag. Generally frames are going to have a pretty similar front on view, the downtube, seatube, etc may be aero, but you'd think the wheels and stuff would affect the advantages that would be gained. Also, Frames are expensive, cervelo soloist carbon is supposed to be the most aerodynamic frame, but it costs a bit, while you can get deep carbon wheels for 1/4 of the price. You're pretty much always racing in a bunch unless it's a time trial, so the aerodynamics have less importance again. You'd be better off getting into the best position behind the other riders, especially in a cross wind, as an aero bike isn't made to be aero to the side.

Also remember, you have to have the engine to generate the power. Not much point trying to reduce the power requirements unless you already have enough to compete. Once you can compete, you can think about where to get the advantage, but good wheels are always nice to ride.

[mikesbytes]

Why would lowering your handlebars reduce power output?

[Simon Llewellyn]

In truth i don't think that lowering you handle bars does reduce power output. Have you see theo bos's position lately? I mean i though my track bars were low... If he was any lower i think his back would snap! & he is the fastest man in history, well with the fastest flying 200m in history....

http://www.nrc.nl/sport/article585657.e ... ij_NK_baan

That sort of position does compress your lungs though & on the track it probably doesn't matter so much, well it mustn't because every body does it & it is fast. But on the road over a 40-60km time trial when your body has time to mount up a good oxygen deficiency it will do damage i would assume & that's what i've read. & that's only 40-60kms, over 100-160kms you'll be in abit of trouble. & as James says in a bunch it becomes void anyway, aero dynamics don't matter, stiffness and good quality hubs do though...

[T-Bone]

It depends how much you lower your bars. Any change in position will require time for your body to adapt as well, but i think on the road you have to consider a certain amount of comfort is required, especially when riding 4-5hrs+. You can save more energy with good positioning in a bunch rather than aerodynamics.

It won't hurt to try lowering your bars, just remember you can always go back to your old position, and make small changes to enable your body an easier time adapting.

[mikesbytes]

I think you have a point about the breathing, I can see how your lungs will get cramped, particularly if you have insufficient flexibility in the lumber and hip areas.

I lowered my bars about 8mm earlier this year and it did take a couple of weeks to get use to it. I'll lower it another 8mm and see how it goes.

I wouldn't mind trying a longer stem, but one change at a time.

[Kieran]

A few points.

My frame cost me $600. It is very aero.

When you lower the bars you put more weight on your hands, put stress on your back and tend to cramp your legs and chest. You can get around the last problem by running a steeper seat tube as in TT frames, although there are UCI limits. This opens up the hip angle.

I am pretty flexible , and if you have a look at my bike you will see I have a steep head tube and very very low bars. It is comfy for me but i don't think many people would be comfortable in that position for too long. Note that becuase of the steep seat angle my knees are a long way from my chest.

You can lose power if you cramp up too much. There is an ideal thigh to torso angle that you can't muck around with too much.

See an excellent series of articles on the cervelo website.

This one deals with TT tri fitment but the basic principles apply to all bikes.

http://www.cervelo.com/content.aspx?m=E ... TriBikeFit

[mikesbytes]

Thanks for the link Kieran. I was looking quite closely at your riding postion on Sunday as you probably have the lowest postion of all. I have been working on my flexibility over the last year or so and I seem to be able to crunch my body down and then roll it forward on the hips to free up the chest. There's still some work to do in this area, but I'm heading in the right direction. I could also do with a longer stem, as when I get into that position, my knees can hit my elbows if I don't keep them out of the way.

Stuck with the frame I have for a while, but when I do get a new one, I have a lot of ideas about what I will want.

I'm away today and tomorrow, when I'm back I'll put the bike thru that maths in the link and see what comes out.

[Simon Llewellyn]

You guys have got to check out this time trialling position, it's hot!!! Look at how low she runs the stem/s...

http://www.yvonnehijgenaar.nl/fotogallery.htm

http://www.yvonnehijgenaar.nl/fotogallery.htm

http://www.yvonnehijgenaar.nl/fotogallery.htm

It's partly to do with the BT geometry but it is still a mean looking position....

[mikesbytes]

Try this link

http://www.yvonnehijgenaar.nl/fotogalle ... e_2006.jpg

[weiyun]

Is there actually a difference in position? I thought it's just change in the hardware, giving an identical position as in the drop.

[mikesbytes]

What I figured out is that you loose power after bending the body past 90deg, so the amount of aerodynamics is limited by the angle of your seat tube, which on on OCR is relaxed, although I could put the seat forward a little, but does it affect your knees putting the seat forward?

[Simon Llewellyn]

Higjenaar's position is actually ridiculously low because even though it looks as though if she would use standard drops it would reach about the same area, look at how her hands are basically at the same level as her front tyre & think about how high above the front tyre they normally are.

http://static.flickr.com/45/126780109_4489fb3978.jpg

For example check out Theo Bos's position, he is in incredibly low, this would put alot of pressure on the groin but still he has a noticeable gap between the bars & front wheel. Thought he is a fair few feet taller than Higjenaar.

http://www.tourpress.nl/materials/pers_ ... eo_bos.jpg