Stealth bike tech of the year: Rule 28 aero base layer

@Rule28 I’m sure you’ve seen the Nopinz aero data related to the aero base layers. Are you aware of how they performed the, “Direct Aero Base Layer Comparison” ? Was the base layer and matching suit used from each competitor or did they just use the base layer from each competitor in one of their suits?

Also, do you have any thoughts of opinions?


Yes, we’re aware. They haven’t deemed to provide any more details on their protocol besides the numbers. Eg, what sizes was used, what suit were they tested with etc. They also haven’t provided any of their base layers to be independently tested at the SSEH unlike us and HUUB so no one can repeat their testing.

In our testing, our base layer outperforms HUUB’s but I’m sure HUUB have testing to show the opposite. Anecdotally we’ve heard that the majority of riders testing at the SSEH find our base layer works with their suits best. The HUUB one tends to need their suit to work.

What I would say is that the Nopinz approach is opposite to what we and HUUB have independently arrived at in regards to rib spacing. Their wider spacing is counter to what the theory says is optimal for our target speeds.

We are wary of publishing direct comparisons between suits and base layers because there’s a huge difference in how they can perform between different riders. We make suits for some WT team riders as they outperform their sponsor suits, but not all the riders find gains.

Things like socks, where the variance in leg shape from person to person is minor allows for fairly consistent comparisons to be made, which is why we did publish a comparison of aero socks.

Always be wary of what manufacturers say, especially if they don’t publish the protocols etc. we could test 100 times and publish the 1 result in which a bad garment outperformed a good one.

We stand by our product and have it widely available to test independently.

Hope this helps :+1:


Let us know how you get on!!


@Rule28 is it hard to make a water bottle designed to go between the front of the jersey and the rider? It’s faster, of course, but it just gets uncomfortable after 30min or so with a regular bottle.

Hmm so for a Castelli San Remo suit it might be a pretty decent benefit due to the tight, thin, flat sleeve fabric? Interesting…

Awesome results!

Yes, it’s only designed for use with smooth sleeved arms. We advise that it’s only used with smooth armed suits like our Neo Suit. There are some textured/mesh suits it can work on but not many (and this may very depending on the rider) so it’s not something we recommend unless you can test it and don’t have to worry about getting bad results (costs etc.)

NZ Track squads have used it under their semi textured suits after finding good gains.

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The two layer system is core to how it works. The theory is too long for here but tl;dr it basically makes a ‘smart fabric’. In high pressure, the ribs are pushed more, creating more pronounced structure. In low pressure, the reverse. The fact the surface can be a low skin friction fabric too, without rubbing itself also aids performance.

Full write up available here:

The fact that it’s a base layer makes it a retrofittable - we wanted riders with exiting kit to be able to use it, which is why we’re being used by half the WT and counting now!


Look at a camelback or Uswe. A water bladder is probably ideal for this in terms of flexibility for comfort, easy access (via hose) and come in a verity of sizes.

It’s not something we’ve personally tested but we have seen test data from those that have and it works well.

It might work. Rather on that than on some very 3d shaped fabric. But to be sure there is only one way: test test test. Does not have to be a windtunnel, there are great services that do aero-testing at velodromes (see Rule28 post above who got their material for testing for example), or test outdoors with a Notio, or just by the Chung Method (I hope I remembered that name correctly? In the Time Trial Thread there should be plenty of info on that)

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Awesome product :wink:
It was tested with the guys from, if you are also in charge of the Rule28 Instagram I think you saw the post they made back in the days about our findings.
As you mention them above, did you guys now “sponsor” / borrow them your fast euqipment in various sizes so people can test it there?

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Yes I am. I saw the posts about them testing and they said it performed very well under a mesh suit. I didn’t actually see any numbers from the test results though.

to my knowledge they bought kit from us to test. (For US readers, we’ve been made aware that the Specialized wind tunnel also has done this).

We’re keen to send out kit to any good testing company working on velodromes/wind tunnels too to use in client testing.

If anyone that runs testing sessions sees this, drop us and email and we can sort of a collection of test kit.


Hi Lars,

have you been able to do some testing with the suits.

I use the Nopinz Flow Suit for the 2023 season but I am in the market for a new one.

Is the Rule 28 Neo noticeable faster for you than the Flow. What about the Nopinz Hypersonic?

Guess you owned (and tested) all off them?

I am also 1,90m tall and use a position close to yours because of UCI regulations.

Thanks a lot!

Has anyone tried the Aerocyclinggear Baselayer?

Ordered the Rule 28 base layer recently but had to send it back because my arms wouldn’t fit in the largest size :rofl:

Aden from Aerocyclinggear said they would make a size that could fit a more muscular guy like me with bigger arms and now i’m curious about the performance of their base layer.

@Rule28 is there a rule of thumb of how watts saved from x item to how much is gained while on the wheel? For example, let’s say base layer saves 20W at 50kph. If you’re on the wheel at 50kph, how much is still being saved?

The short answer is it decreases proportionally to the total amount saved through drafting (30-50%).

The long answer is it varies with a few number of variables:

Socks/overshoes are less effected by drafting than a suit as the volume of air being displaced is less at that height meaning the effect of drafting is lower. Therefor the savings of aero socks as a % of overall drag when drafting is greater.

Distance to rider, CdA of rider, yaw angle etc will all effect this.

We do all our product testing in the wind tunnel to control these variables. Real world testing with an aero sensor would be needed to test this.

It’s an interesting idea and we will look into producing some content about this for next year.


if you take there testing as true the black bibs skinsuit is just as fast (within one watt) and the black bibs stuff is only $150. maybe their testing isn’t good?

Has Rule 28 ever released data on whether the road race skinsuit is faster with or without the aero base layer?

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Noticed Tadej was wearing the long sleeve castelli version of this at the Giro TT.

Maybe this will help?

Tempted to use the strava castelli discount to get a bolero, but the sleeves are a bit short on the short sleeve one and I don’t like that it’s either a full baselayer or just a strip around the back.