I believe narrow is faster for most. It makes shrugging more comfortable for me. Shrugging and turtling will me you faster.

If you can already shrug and turtle then you are probably most of the way there.

Put a mirror in front of the bike a look at your frontal area with your elbows an inch closer. That should give a pretty good indication of the aero impact.

it depends - sorry there is not an easy answer to this without some form of testing. You might narrow and get your shrug on, or you might narrow and pop your head up. And possibly either would be better/worse.

Isn't aero fun.

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I want to try it out, but it's $87.50 including shipping for a pair of Tririg arm rests.

Ok, thanks. Let me set up my trainer and try this.

I just picked up a pair of TriRig armcups and they're fantastic. I much prefer the material of them to the traditional more fabric like foam of profile design. I'm coming from some very decent vision ones as well. You won't regret buying them.

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It is possible to go too narrow, and narrower setups will create arm/shoulder fatigue for some. A good rule-of-thumb is to have the spacing set so that your upper arms are in the center of your quads (helping to shield them).

Here's an example of it being done well:

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When you say narrow what measurement is that?

I didn't know about this. This is a great information. Thanks!

Good to know!! Thanks for your feedback on them. I was curious how they feel.

while that might be a rule of thumb, I would not call it good as it is not true for all folks. for some, it is really slow

I was referring to pad width.

Titanflexr offered the arms shielding thighs guidance, which seems sound.

I’m a bit narrower than that, but I have broad shoulders and for me it is more important to get my shoulders and head out of the wind.

I ride Sprint to Oly distance - so, not really concerned with fatigue the way I would be if I was on the bike for an IM distance.

If I invested in testing time / $ then I would play with it a bit more.

Narrow is not always faster...it tends to be but not always...just the same as going lower.

Keep in mind fatigue, BTA placement, and how it can affect your head position.

Lastly, how do you plan to test it out and confirm? The arm cups arent expensive, but figuring out if they helped can be...If you arent prepared to confirm this, then just stick with what you got

I drilled the holes and now they are about half inch closer to each other. I feel more locked in and secure this way.

I hope you are just doing that as a temporary test. Because I don't like that modification AT ALL, from a structural safety point of view. WAAAAAY too much opportunity for stress failure.

That's a good way to find out how good your helmet is.

I suspect that is a minor consideration looking at the minuscule amount of drafting you'd get. And add a little yaw...

If you are closing off the gap between your arms with your head and hands, that seems like a it'd be winner. But if the gap is there then making it a bit smaller won't necessarily help. The effect on shoulder posture is probably a bigger consideration.

Profile design race arm cups are only $48 and are fantastic

I dont quite see it like that.

I'd defo make sure there are no nicks / notches and smooth everything, but otherwise the weakest cross section is unchanged - as there has been no metal removed from the 'line' that runs front to back through the centre line of bolt holes. Also with moving the pad inwards there is less bending moment on it (it is less cantilevered outwards).

I can only go as narrow as my arms about middle of thigh. I have wide broad swimmer shoulders and it hurts after 15-20 mins when they are too narrow. Comfort over a 100 mile bike will usually benefit me for than a few % in aero gain

I tried them already but they raised my elbow position, so no go.

I'm 128lb and already rode 200+ miles with this setup. No problems at all.
Those are old Profile Design arm rests and they are really solid. There's no way I can break or bend with my strength and weight.

How much the bending moment changes and in what direction is a function of the total load placed on the pad (in addition to the arm length). Yes, they've moved inwards slightly (to shorten the arm). But, the elbows may have moved from a less vertical to a more vertical position, which would increase the verticle load, and may result in a net INCREASE in bending moment. The elbow contact point (typically the start if the radius cup) is still well outboard of the mounting screws. Removing the material between the two screw holes (one slot, and one hole) will allow the material to deform under load. Further, the old slot that has been cut across (to create a "t" shape) now become stress concentrators.

*I* wouldn't ride it for more than a 20m test ride or two on a known smooth road. No way *I* would ride anywhere I could experience a significant shock such as a pothole. The consequence for an unexpected front end structure failure is just too great.

But, thats just one engineer's opinion.

And mine was another engineer's opinion 😁

First one to get out NASTRAN wins. :-)

A few years ago i used Aerolab in golden cheetah to test arm rest positions. My arm rests had holes for 3 widths. The most narrow position was fastest. The widest position was next fastest. The middle position was slowest. It seemed weird, so i tested a couple more times and repeated the same result each test.

I would have expected the middle position to be about halfway between the other two, but it wasn't. Aero is weird. The best way to determine whether something is faster or not is to test it. I imagine for some people the middle position would have been fastest and the other two would be slower.