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Aerodynamics

by Paul5f
Tue, Sep 06, 2016 10:01
11

My question is simply, is there anything I can do to improve my aerodynamics? Are there any changes to my bike that will make a big difference?

After 20 years of mountain biking I've recently purchased my first road bike, a Canyon cf 7.0 sl, and I'm quickly realising how important aerodynamics are in road cycling.

Also, the wheels/hubs on my bike feel a bit, well not quite what I was expecting. I only have my mountain bike to compare them to but the Bontrager wheels and hubs on my Klein mountain bike give the feeling of my peddles being attached directly to the rear wheel and instant power transfer, but with the Mavik Aksium wheels I don't get the same feeling, they feel more spongy and less efficient. Would a more expensive set of wheels make a difference? I was looking at something like these Hunt wheels which I could buy now

http://www.huntbikewheels.com/collections/road-rim-brake-wheels/products...

or would saving up for a pair of deeper section cf wheels like these be better?

http://www.chainreactioncycles.com/mobile/shimano-dura-ace-9000-c50-clin...

My rides are between 30 and 100km and I live by the south downs so don't climb anything too extreme, its more lumpy with the odd section of around 10 to 13%, but things can get a bit blowy along the coast or up on beachy head.

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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11 comments

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Anthony.C | 7 years ago
0 likes

Aksiums are a bit heavy and uninspiring, if you want to spend 400 quid on wheels forget the Hunts with their cheap, generic components, the new Mavic Kysrium Elites would be a significant upgrade and more aero than the old version..which weren't aero at all.

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Dnnnnnn | 7 years ago
1 like

To echo the sensible comments made above, by far the most un-aero thing about your bike is YOU!

All the kit is (expensive) marginal gain when you've sorted out your riding position.

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ChrisB200SX | 7 years ago
0 likes

Bin the mavic wheels when they break or wear out, get aero wheels when you need new wheels. Unless you are racing?

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The _Kaner | 7 years ago
2 likes

Getting back to one of your original observations regarding the lag you feel in acceleration from the Aksium wheelset compared your MTB...is the MTB a 26" wheel? It might just be that the smaller mtb wheels with stiffer spokes combined with the particular pawl engagement set up gives the impression of faster acceleration. Aksium would be at the lower end of the spectrum regarding Mavic wheels...but I'd not go for a change of wheels this early on in the bikes lifespan...especially as winter is approaching...if you still feel like you need a new set after winter then the Hunt wheels are an excellent choice for a modest outlay.

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part_robot | 7 years ago
0 likes

Here you go: http://road.cc/content/news/133598-want-ride-faster-hunker-down-hoods

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part_robot | 7 years ago
3 likes

Regarding Griff500's remark above:

Wind tunnel studies have shown that using drops is not as aero as using the hoods but lowering your back such that your forearms are parallel to the ground. Using the drops increases frontal area due to exposing more of your arms to the flow.

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Griff500 replied to part_robot | 7 years ago
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part_robot wrote:

Regarding Griff500's remark above:

Wind tunnel studies have shown that using drops is not as aero as using the hoods but lowering your back such that your forearms are parallel to the ground. Using the drops increases frontal area due to exposing more of your arms to the flow.

I can see this developing into a my data is better than your data thing, so here goes:
CdA measurements by Cycling Power Labs:
Tops .408
Hoods .325
Drops .307
Aero bars .268

Avatar
700c replied to Griff500 | 7 years ago
1 like

Griff500 wrote:
part_robot wrote:

Regarding Griff500's remark above:

Wind tunnel studies have shown that using drops is not as aero as using the hoods but lowering your back such that your forearms are parallel to the ground. Using the drops increases frontal area due to exposing more of your arms to the flow.

I can see this developing into a my data is better than your data thing, so here goes: CdA measurements by Cycling Power Labs: Tops .408 Hoods .325 Drops .307 Aero bars .268

I think the point is that you can use the hoods, with a flat back and bent arms, forearms parallel to the ground, and it's very aero. Similar effectiveness to the 'invisible aerobar' position adopted by pros. 

Obviously hoods with straight arms is not going to be aero, though it is comfortable!

Personally I mix all three on any ride - fast descending I'd certainly use the drops. To get any faster using the hoods or tops on a descent would require 'Froome style' sitting on top tube and I'm not that brave or talented!

Avatar
Griff500 | 7 years ago
1 like

Rider is 80% of drag. Drop your bars as low as you can, or are comfortable with, and use the drops at speed (it's amazing how many people ride hoods all the time), also keep your head low. One of my bikes has a relaxed setup, with the bars 7cm higher than the other which is aggressively set up. There is a massive difference in effort above 20 mph, or into wind.

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Paul5f | 7 years ago
1 like

Thanks, interesting video and channel, I'll forget about the aero wheels.

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TypeVertigo | 7 years ago
1 like

There was a recent video by GCN that tested which method of gaining aerodynamics actually netted the most benefits: riding position, kit, or wheels.

The big winner by far was riding position. Wheels were a distant third.

Before you decide to blow off your budget on a swank pair of wheels perhaps you should try watching the video.

https://www.youtube.com/watch?v=9I02BKm4ZiM

Not the most scientific, perhaps, but it's a good resource for your purposes.

Now if you're really dead set on buying a better wheelset with better freehub engagement and power transfer, then go ahead. Good luck

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