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Feb 2016
2:33pm, 18 Feb 2016
148 posts
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Dingley
Having fitted a set of deda clip on aero bars to my felt road bike (F85) I find them uncomfortable after not very long at all, does anyone have any ideas as to how I can improve my position? if not they do make a rather nice helmet rack while in transition I suppose
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Feb 2016
2:48pm, 18 Feb 2016
12,345 posts
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TRO Saracen
1. Sticking clip ons to your 'normal' road position will not be comfortable (or very aerodynamic), you will need to alter other things about your bike ( saddle forward/back position, front stack down etc). If you get that right, then riding the bike in roadie position will now be uncomfortable. You will probably need a new TT specific saddle to avoid crushing the gentlemen's vegetables. A road bike will inevitably be a compromise compared to a pure TT bike due to frame geometry, but you can get a good way.
2. TT position is uncomfortable to some extent, you need to get used to it, train yourself to tolerate it by spending lots of time in it. Neck and shoulders will ache so you will need to build up how long you can hold position.
3. Savings will only be had if you can ride most of the time in the position (ie anything except sharp braking, sharp corners etc). Thus get used to cornering by leaning etc.
4. Don't forget to shave your legs, buy a skinsuit and a cock lid and as Greppers says, at least there's no need to wash with soap any more.
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Feb 2016
3:32pm, 18 Feb 2016
152 posts
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Dingley
many thanks for the sound advice my good friend, will definitely start with some saddle play, oo-er matron! The leg shaving, not so sure about but then again don't knock it 'til you've tried it!
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May 2017
10:39am, 25 May 2017
60,704 posts
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Gobi
I'm going on the velodrome to do aero testing on 2nd June.
Taking lots of bits.
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May 2017
11:06am, 25 May 2017
15,045 posts
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The Teaboy
Any position that gets you more aggressive will also alter your hip/back angles. Lack of flexibility in the glutes/hamstrings and lower back can be a problem. It can also induce more strain in neck and shoulders from having to effectively look up to a greater degree to see where you are going.
It can also feel like constricting your breathing, so balance needs to be struck between most aero position and position where you can generate the most power for a prolonged period.
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May 2017
11:15am, 25 May 2017
15,046 posts
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The Teaboy
I'd argue that a simple test might be to use an iPad or similar to take photographs of you in profile and head on in different positions - perhaps on a turbo.
You can then do direct comparisions of your frontal area and perhaps gain an appreciation of the wattage you can output under those positional conditions. The absolute value is less important than having a good comparative baseline.
Aero drag = 0.5 x air density x velocity squared x frontal area x drag coefficient.
So its possible to work on your frontal area by inspection alone. Any improvement or reduction in power will need to be square rooted to compensate for the velocity squared term to give an idea of how your overall combination balances out.
Drag coefficient is not possible to measure without a wind tunnel or some CFD modelling, but things to look for in the profile shots are the flatness of the back and the interaction between helmet and airflow. If you have an aero helmet, depending on the design, it can actually be worse depending on your head position. If you have a long tail but ride head down so the tail sticks up into the airflow, it can cause more drag. The rounded type (see the Kask ones Sky have ridden with) may not be absolutely optimal for all conditions, but avoid the worst case scenarios.
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May 2017
12:19pm, 25 May 2017
60,707 posts
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Gobi
Teaboy - are you a time trialled/CFD MODELLER ?
you speak well about all the things that I know and have played with.
I'm a 20 min 10 mile tester who puts out 320 plus watts and have been bike fitted. I own an array of helmets and gear. Photos have been analysed and experiments done.
I am going to work with one of the countries leading positional experts.
Power profiling and cfd modelling is part of what is going on.
This is a big outlay as I need to know 
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May 2017
12:26pm, 25 May 2017
12,324 posts
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Nicholls595
I like the mint ones best
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May 2017
1:06pm, 25 May 2017
15,047 posts
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The Teaboy
Gobi. I have degrees in aeronautical engineering (I specialised in the aerodynamics elements as I had dreams at that stage of designing F1 cars) and sport science. I'm not a time trialler, but I guess I'm on the knowledgeable side for an amateur!
I was just trying to illustrate a process by which an amateur with a few simple tools could replicate a large chunk of the effects of an expensive process with stuff they had lying around!
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May 2017
1:27pm, 25 May 2017
60,709 posts
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Gobi
Teaboy- cracking degree indeed. As I said you spoke very well.
This is the final TWEAK after a lot of time playing .
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