So Specialized finally figured out how to make a brake track that doesn't dissolve down a good descent-make a disc wheel.

Development notes: Specialized developed the CLX50 around a 24mm wide (spec) tire which measured 26mm when mounted. It appears they developed the rim around their own 24mm S-Works Turbo/Turbo Cotton casing. What's interesting is that they have a graph showing rotational+translational drag.

My thoughts:
-The 454 NSW certainly doesn't seem to bring anything game-changing to the party. IMO it better really be 303 stable if Zipp wants to justify its existence.
-I wonder how much better the Zipp wheels would have tested with a 23mm GP4000 SII? That seems to unofficially be Zipp's go-to tire.

they would be better with a supersonic tire

looks like power to spin is negative from the unlabeled graphs

Too bad they didn't publish rotational drag. It would be interesting to see if the study on JackMotts site reported similar values.

Also, as I read this it looks like they were designed around the Specialzed Turbo tire, but it doesn't talk about the Turbo Cotton.

They tested with a 24mm Turbo Cotton

Nope, they were tested with their Turbo tire:

"Win Tunnel testing were all done around a Specialized S-Works Turbo 24c tire (measuring ~26mm wide)"

It's nice that they included rotational drag, but then they go and mess up the axis (and I would like to hear how they measured the rotational drag, by the way). Why include units on the axis if you are not even going to put numbers on it?

Ah, thanks. I could have sworn they said Turbo Cotton somewhere in there.

Would rotational drag vary much between wheels of of the same rim depth? I imagine that the rotational drag is largely driven by spoke choice, and since there are so few choices when it comes to aero spokes it seems like they would all be very similar.

They did.


"The same tire and pressure was used for all testing – a Specialized Turbo Cotton 24c @ 100psi. (Actual measured width is noted in the graph)"




Confusing. Early on they claim they designed to tire around the Turbo S-Works Turbo 24c, but then they publish competitive test results using the Turbo Cotton 24c. Perhaps the performance delta to Zipp was less impressive on the S-Works Turbo?

---

"They're made of latex, not nitroglycerin"

I'm pretty sure the two tires are dimensionally identical.

Perhaps. This paper seems like it was done in a bit too much of a rush without proper review (mentioning different tires, no numbers on the axis).

I don't think so. IIRC, if you look at Tom A's wind tunnel data you will see that the Turbo tire is much more aero than the Turbo Cotton tire. I believe the manufacturing methods are different (with the Turbo Cotton being a "open tubular", whereas the Turbo is not).

From the graphs it actually does look more like it's the Turbo Cotton being used, since the drag is not decreasing much at yaw - which it usually is with a more aero tire.

They may have similar nominal specs, but the construction of the two is quite different and they presumably shape differently when inflated to the same pressure.

Tom Anhalt wind tunnel tested both (along with various other sized Specialized tires) on the same wheel (CLX64) and found considerably different behavior at yaw angles beyond 5*.

---

"They're made of latex, not nitroglycerin"

Actually, it says they designed around the S-Works Turbo, but the testing was with a Turbo Cotton.

I'm dismayed by the lack of units on the charts...at least tell us what each division represents. Otherwise, there's no way of knowing if we're looking at small or large differences :-/

Are the quoted wheelset weights with, or without braking discs attached to the disc models? My bet is "without", based on the Enve and Bontrager weights. If that's the case, then this is the second example of the wishful thinking about disc rims being able to be lightened enough to overcome the weight hit of de-integrating the braking surface not coming true...

I'd also like some more information about the "rotational drag" and how that was measured, and then "translated" back into an equivalent CdA. Is it possible the "translational" and "combined" values are just the drag measurements from wheel-stationary and wheel spinning measurements? If so, then that's still missing the "power to rotate" contribution.

I DO like the fact that they do what they can to increase spoke bracing angle. Even small changes in that can have relatively large lateral stiffness effects. Damon Rinard found that out a long time ago when he looked at the lateral stiffness of a radially laced wheel, where the only change was a "spoke heads out" vs "spoke heads in" configuration in the lacing :-)

---

http://bikeblather.blogspot.com/

They aren't...just because of the construction. There's a "lip" on the TC where the tread is glued to the casing that's not present on the Turbo

---

http://bikeblather.blogspot.com/

I see that now. Confusing. Smells a bit like the Turbo Cotton gave better results compared to Zipp (like mentioned above). Why else not use the tire you designed around? (Maybe they should have designed around the Turbo Cotton in the first place, but that's another thing).

Yes, at least give us numbers for the divisions. I can see Mr. Yu cringe as he saw what the marketing department ended up with for a final release of this paper :p

It was a much more aero tire on that wheel. It may or may not be the same on a different wheel.

---

"They're made of latex, not nitroglycerin"

Ah, gotcha. I wonder how it would have fared with the 24mm Force. That seems to be like a really good bet on the new generation of ultra-wide wheels.

True. But judging by how all "open tubulars" seem to do in aero testing (i.e., early stall), I wouldn't bet too much money on the Turbo Cotton being an *aerodynamically* good choice on any wheel.

Yeah...but they're not likely to show data of their wheels with other brands of tires ;-)

---

http://bikeblather.blogspot.com/

You're probably right. But, as Tom says, "low Crr can make up for a lot of aero sins" ;).

---

"They're made of latex, not nitroglycerin"

That's Dr. Yu now ;-)

Here's the thing about Turbo vs Turbo Cotton...as we've seen, the much lower Crr of the TC tends to make that a faster choice overall, especially for racing. I have no problem with them using that for the aero testing, since that's the most likely choice for a racer to use...AND it more closely represents their fastest tubular tire offering as well.

In other words, don't get caught up in chasing high yaw angle performance of tires that aren't as low of a Crr...that's not "keeping your eye on the ball", so to speak.

---

http://bikeblather.blogspot.com/

Yep, it's probably still the faster of those two tires on most/all wheels when taking Crr into account :)

Him being a Dr. just make me think he cringes even more ;)

I know, the TC is most likely the faster tire in most circumstances. Which is why they perhaps should have designed around that. But then the graphs don't come out as nice! So you got to figure out if you want to go fast or look fast (lucky for me a lot seem to go for the latter! ;) ).

Hey gang, I'm running between tests and meetings this morning but rest assured answers are coming. All great questions.

Hey all,

Thank you for the comments - we're working to be as thorough as possible with our data. We'll work through these questions as quickly as possible.

To answer the Y-Axis unit scale question - the divisions on the graph are 0.001m^2. The range for each graph was 0.020m^2. Ultimately, we decided to not include specific absolute values as testing set up (facility, fixturing, build, even the actual tire used) can cause differences in the absolute values between tests. All of the data collected in these graphs was collected in one test session, (though deltas were confirmed on multiple test sessions), same exact tire for all tests, and inflated to the same pressure. We will answer the specific rotational drag questions shortly, but the rotation drag was always an addition to the translational drag. The graph's range just shifted slightly higher.

Chris can discuss further on the tire choice and development of rim shapes, but the Turbo Cotton tire was selected for drag testing to show the fastest overall package (translational, rotational, Crr).

Cam

why didn't you include aero results for the enve 4.5? weight comparison given where you come out very well but then no aero - did you lose?

roval wheels have always done well on weight, often at the expense of other qualities...

Thanks Cam. I realized after I made that post that I could just scale the units off of the plot you did last year with all of the S-Works Turbos and Turbo Cottons on the CLX64 wheel, which included the TC 24...which is posted right on my blog :-)

---

http://bikeblather.blogspot.com/

I am particularly interested in how you set up the Win Tunnel to measure rotational drag. Some other questions:
1. What is the difference between a radial 20 for a rim brake and a 2-cross 24 for disc wheels?
2. Flat vs round spokes. The testing of the Rail wheel was 1 watt of translational drag, but there was no rotational measurement.
3. How about some different tests of wheel-fork interaction? Can you answer the wide vs. narrow fork question?
4. Tri-spoke vs. 20 spoke vs. disc. Rotational drag difference?

P. S. If you need a set of Specialized Tri-spokes to test the last 2, I have a set you can borrow :-). I would love to know if my Tri-spoke front, with a 20mm SS, still rules on my Nose-cone Shiv at low yaw angles.

I make so many writing mistakes that it is unreal, but how do they mess up "Aeolus" repeatedly in this.

---

---

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

Ok, to answer some of the questions in this thread:

- Turbo 24 vs. Turbo Cotton 24: Simple explanation - when we started doing the shape design of the current family of CLX wheels (32,50,64) the Turbo Cotton didn't quite exist yet. All our historical CFD and benchmark data was based off the Turbo 24. As you can imagine, it takes a while to fully quantify and correlate a non-exact shape like an inflated tire casing. However, the comparison testing was done much more recently (e.g. includes the recently launched Zipp 454) and in our testing, and as Tom A. pointed out, the fastest combination of translational drag, rotational drag, and Crr was with the Turbo Cotton tire. This was true for the Zipps as well. As a result, we felt it would make the most sense to publish comparison data using the fastest available total combination.

- Rotational drag ("power-to-spin"): As many of you know, it is extraordinarily hard to be able to reliably/consistently measure this with adequate resolution. Then there are complications like accounting for, or isolating tire Crr or bearing drag. In fact, Tom A. probably remembers us telling him we were working on various different methods (most of which we ditched) to do this in the Win Tunnel when he visited over a year ago. Our engineers recently developed and validated a protocol and equipment to be able to isolate out the rotational aerodynamic component at a resolution of ~50 mW. Since we devoted a lot of time and resource into developing the equipment and protocol to achieve this, I think you'd understand if we'd like to keep the specifics proprietary. Hint: involves a very careful and modified application of the Chung method in the tunnel while understanding what error terms can be neglected vs. not.

Anyways, a lot of geeking out. The CLX50s are FAST and ride very responsively.

Chris

Sounds like you found another "nail" for RChung's "hammer"...cool :-)
(Now I'm going to be racking my brain trying to figure out how you do it...does tire Crr come into play at all?)

So, on the plots that show the combined translational drag, they show the units as m^2 of CdA as well...does that mean the "power to rotate" varies in proportion to V^3, like the translational drag? Do you think the differences between the CLX50 and 64 are just the different spoke lengths? Or, is something else at play?

---

http://bikeblather.blogspot.com/

Thanks for coming by and talking about these in some detail.

Hubs are a major drag component, and are hardly ever optimized for aero in the way that rims or frames are. Could you tell us more about what you've done with the 'Aero Flange' hubs?

And what explains the large low-yaw rotational drag advantage of these over the 808 NSWs?

---

'It never gets easier, you just get crazier.'

Thanks for the reply. It is always cool to get insight from the engineers that really know the how and why of what make a bike fast.

Your Chung clue is intriguing, but VE doesn't make much sense to me when there is no elevation change.

I always wondered why windtunnel a don't measure current draw for the motor that turns the wheel at the wind speed of the tunnel. Don't watts = amperagexvoltage and you "know" tire Crr from roller tests. You could then measure bearing drag on a seperate fixture and sutract from the wattage consumed by the motor. This is a kinda piecemeal way to calculate rotational drag, but is there something I am totally overlooking?

I'm going to have one of our super engineers (Ingmar Jungnickel) who helped develop this method jump in to explain a bit about how CdA plays out in this situation. As for your question re: differences: spoke length certainly plays a big part. But were also able to measure differences in how different rim shapes, hub flanges, and tires rotate through the air.

You answered your own question ;-)

In theory, that's sound. In practice there is a huge error stack on a (relatively) tiny signal.

Well, they're very nice bearings. You've put together a tidy system which justifies the investment.

---

'It never gets easier, you just get crazier.'

Even small changes in that can have relatively large lateral stiffness effects. Damon Rinard found that out a long time ago when he looked at the lateral stiffness of a radially laced wheel, where the only change was a "spoke heads out" vs "spoke heads in" configuration in the lacing

I could be mistaken, but I recall Jobst writing about that well before Damon came on the scene. (RIP Jobst)

Your Chung clue is intriguing, but VE doesn't make much sense to me when there is no elevation change.

The "V" is for "Virtual". Doesn't mean that you need real elevation change. The genius of the Chung method is that it represents energy changes in terms of elevation changes for the bike and rider, which are more easily conceptualized. More generally, the Chung method is an example of kinematic modeling, which is what I think Chris is hinting at.

The physics was worked out long ago. Once, there was an internet far, far away, where a physicist named Schreuder documented all this, and worked it out for the special case of the bicycle. Unfortunately it is mostly gone now, although tantalizing hints remain: http://forum.slowtwitch.com/...ost=2759184#p2759184

Proving, once again, that the gap between theory and practice is larger in practice than it is in theory.

The requested URL /metingen/measurements.html was not found on this server .. http://www.xs4all.nl/~cp4trml/metingen/measurements.html .. any other publications ore sources out there?

---

*
___/\___/\___/\___ the s u r f b o a r d of the K u r p f a l z is the r o a d b i k e .. oSo >>

Schreuder's pages seem to have disappeared; I can't find them even on the Wayback machine. But the Chung method should get you to the same place, if you're trying to get to rotational drag from Chris' hint. That's just my opinion since I haven't worked out the trick. Viel Glück!

I'm always shocked , ok not shocked, by how closely bunched the transitional drag numbers are for different 'aero' wheels at 0-5 deg yaw.

Differences between set ups appear usually only at higher yaw angles

Is there some kind of inherent min at 0-5 deg yaw ?

Does nothing behind the leading edge really matter at 0-5 deg and hence "they" all are very closely matched ?

Chris,

I'm moving to disc brakes as we speak & your release couldn't be more timely. I've asked my LBS, who tells me you've already got these in stock, to grab me a pair.

What kind of overall penalty will I pay with 26c Turbo Cottons? The Crr would be slightly better and the aerodynamics a bit worse, correct? Given the 29.5mm width of the rim, I'm hoping it's still a very fast combo.

I'm a road & crit racer chasing that Cat 1 upgrade this year. The increased comfort and grip associated with a wider tire I can run at 10% lower pressure is (wholly subjectively to me) substantial.

Also, has anyone tested the Crr of the S Works Turbo tubeless? It'd be more aero than a Cotton, right? Still a very fast tire, I'm guessing? Again, for my discipline, the extra flat resistance could be totally worth a small enough resistance penalty.

Congrats on the new product release!

We should compare aerodynamic torque results some time between my 6 component axis data and your method.

If I had access to a tunnel that didn't have a 6 component balance and wanted to back my way into aerodynamic torque, I'd pursue this setup:

http://www.biketechreview.com/...w_negative_watts.wmv

then do sweeps on starting coast down speed and wind speed all while measuring rotational speed and axial force as a function of time (#3 on the list here). One ought to then be able to calculate/model bearing torque, moment of inertia, and aerodynamic torque...am I close?

---

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================

Good work Specialized. Pretty amazing stuff. Glad to see a bike company reporting the whole picture.

So you tested the Turbo Cottons as the overall fastest combo among those two tires, but what about competitors tires such as the: Supersonic, Attack, GP4000s, and Force?

---

---

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

Very cool. I've had some ideas about that but of course I've never had a chance (or the equipment, or really, the time) to test them. Very, very nice.

From a development standpoint, it would be useful to isolate rotational aero drag from bearing drag. From an end-user's standpoint, it doesn't matter. Rotational drag is rotational drag, and if one wheel has less drag than another, who cares what the relative contributions are of the bearings or the spoke/rim/hub aero behavior.

---

"They're made of latex, not nitroglycerin"

Thanks again for that connection. I should have archived his page and images back then. He seemed like a nice guy when I exchanged email with him. I hope he's well, wherever he is.

Yes, I have...not up on blog yet though.


Maybe...but only at yaw angles above 10d, if so.


Ummm...not so much. It didn't roll near as well for me as it did for VN when they tested it at Wheel Energy, despite the 26C being VERY wide (>28mm) when mounted on a rim with an ~21mm internal width.


Not so much...you'd be far faster with a TC w/latex tube (and sealant in that if you're worried about goat heads, and such).

Then again, you are saying that you're a road/crit racer who's switching to discs...so, I'm not sure how much you value overall speed/watts vs other properties :-/

---

http://bikeblather.blogspot.com/

But those aren't Specialized tires...that exercise is left up to you ;-)

---

http://bikeblather.blogspot.com/

Right...I guess I should have said that Damon confirmed it :-)

As long as we're mentioning old-timey internet contributors, I should mention that all of Damon's data on wheel stiffness is still hosted on Sheldon Brown's (RIP) most excellent website.

---

http://bikeblather.blogspot.com/

Hmm. I thought the watts to spin between different wheels would be a pretty strong signal. The Moore and Bloomfield study put the range of wattage values between a disc wheel and a non-aero, regularly spoked wheel at about 10 watts. The difference between a disc wheel (~8 watts) and TriSpoke (11 watts) was about 3 watts. Could you comment on whether the general wattage values in this study are similar to what you find (I.e., the rotational drag on a disc is about 10ish watts)?

Thanks, Tom. I'm fully aware of the weight & aero penalties associated with discs. I hope that the other advantages, especially in rainy crits & on technical descents (both of which I encounter on the regular) are worth the penalty.

I'll take your advice & go Turbo Cotton with latex. I love that tire & actually use it as a daily driver in the summer. Maybe I'll try the Schwalbe tubeless sometime, which I understand also roll quits nicely.

Best,

Mike

Awesome, and thank you. Re: 26 TC vs. 24, it depends (mostly on the road surface/realized Crr difference and your average effective wind vs. ground speed...e.g. if you're in the pack vs. off the front). For some quick and dirty estimates, you can use a total CdA delta of 0.001 m^2 and, say, the Velonews or Tom A. published Crr data on your favorite cycling calculator to see what the tradeoff would be at various speeds (keep in mind: if you're in the pack, the wind speed is significantly lower than your ground speed).

We've found (as has Tom via his blog) that you have to be moving pretty fast on the front or alone for a super skinny tire's CdA advantage to overcome the total combination of something like the Turbo Cotton. Typically >60 km/h

Chris

We've tested a fair number of other tires, but won't claim to know about all of them. But for the ones we have complete data on (like the GP4000s in various sizes), the statement re: Turbo Cotton being the fastest total combo stands.

Chris

These relations of numbers are really interesting and the Chung method has a nice spin to dig deeper, thanks for your reply ..

---

*
___/\___/\___/\___ the s u r f b o a r d of the K u r p f a l z is the r o a d b i k e .. oSo >>

Yes, the total magnitudes you're referencing are in the ballpark for race speeds. However, for R&D and isolating the resulting change of single variables at a time, the deltas are very small. So my fault earlier for misspeaking: the signal isn't small in an absolute sense, the resolution we needed was very high.

Hi everyone,
My name is Ingmar, and I joined Specialized’s aero R&D Department last March. I’m a long time Slowtwitch reader. Before I moved over from Germany, I was an avid triathlete. Right now I am getting settled in the US, enjoying the lunch rides at Specialized and will see if I get into the US tri scene later this year.
I wanted to add a few notes regarding the way we calculate the rotational CdA and the combination with rotational drag. After we established a way of measuring this drag component, coming up with a way to communicate this metric in an accurate and easy to use way was a big part of the project.
We looked at a wide variety of variables to see what impacts rotational drag and therefore how to create an accurate model for future simulations and testing. Testing variables included tire size, tire direction, fork/no fork, air density, bearing drag, relative humidity, airspeed, and wheel speed. From this data we created a model that covers the vast majority of conditions a rider would experience outside:
P = ½*rho*CdA_rotational*v_wheel^2*v_air
If you compare this equation with the translational drag equation, you notice it is almost the same with one difference: Here wheel speed is the squared speed component, while in the other equation air speed is the squared equation. When the wind speed and the ground speed are the same the translational and rotational CdA can just be added But when those speeds are different (due to antural wind), then the model diverges somewhat. In the most extreme wind conditions there are instances where this simplification introduces an error of less than 10% rotational drag (= less than 3% total wheel drag = less than 0.2% total system drag). We feel that with every model of reality you have to balance accuracy with complexity. Directly adding up rotational and translational CdA into total CdA allows to keep the complexity of our model at the minimum and makes the metric easy to understand and use. Our goal is to be transparent and diligent in how we do our research here at Specialized!
We learned a lot through this project, and, as always, answering these questions led to more interesting questions that we would like to find answers to in the future. If there is anything you want me to clarify, I’ll try to check in here from time to time over the next days, so let me know.

Best,

Ingmar

Welcome, Ingmar.

Very cool. I had wondered about a model like this but I was never sure whether the difference would have been empirically measurable. Congratulations on getting it to work.

Hi Ingmar,

It would seem to me that the fork would have the same effect as changing the air density for only the top part of the wheel. I am not an engineer, but I don't see how your model would help you understand or communicate the effect of wheel/fork/frame interactions.

I know Tom A. hates the use of watts when discussing drag, but isn't the power required to turn the wheel really what you are interested in, so it might make more sense to express the total energy to move the wheel in watts at a few common standardized speeds, like 20, 25, and 30 mph?

Hi Robert,

Thanks for the welcome!
Your work was a big influence on my path into bicycling aerodynamics and to Specialized.
It is measurable (at 0.05W, repeatability a lot becomes measurable), but v_air^2*v_wheel is close enough that you do not introduce much of an error. If you would base the equation purely on a curve fitting approach, the reality is a combination of the two (more biased to v_wheel^2). We ended up not going down that path since it added a non necessary degree of complexity and increases the risk to overfit the data. Also it is more in line with our theoretical model.

Halo Ingmar,
Sounds like a very pragmatic, engineering approach. Good stuff.

---

http://bikeblather.blogspot.com/

Hi Mike,

You are right, for studying interaction effects this approach does not add much. But we needed to study interaction effects in order to validate the approach.
If the interaction between different forks would have been so substantial, that you could not compare wheel data from one frame to another, than having a model that allows you to add one CdA to another would not have been necessary and could have been misleading.

Its true, as the rider you want to know if the watt savings from your awesome new wheels helps you beat your buddy who is X-watts stronger than you. But just like your friends power depends on his daily form, the watt savings you get from your wheel depend on changing variables (like the weather, altitude, etc.). If you want to know for sure, you have to do some calculations, and those are done easiest with CdA numbers. If you just need an estimate, we at Specialized use 0.001m^2 CdA (one division in all our charts) [/font]≈ 1 Watt saved at 40 km/h ≈ 1 second saved per kilometer.
If you want to compare wheels from different manufacturers power number can be very misleading. People often get lazy to write down the exact testing conditions and this crucial info gets lost. For example, Germans always report at 40km/h (track riders 60km/h), Americans like 30mph. Some people assume air density is 1.225 kg/m^3, some assume 1.2 kg/m^3 (i've even seen 1.12754kg/m^3) and some seem to use whatever the air density was the day they tested. This makes it really hard to compare manufacturer claims.

I hope this helps

I think you mean 1W~= 0.1s/km ;-)

Yes, your last statement is why I prefer drag reported in CdA...it doesn't require "qualification" to be useful :-)

---

http://bikeblather.blogspot.com/

Wow. I'm sure you're exaggerating but it's nice to hear anyway.


Yeah, the real world issue is whether any estimation procedure is robust for the amount of effort people are willing to put into it. Glad it's working for you.

So would your reply suggest that there isn't much difference between aero forks and that the wide versus narrow fork spacing doesn't have a big impact on rotational drag. Or do I have to wait and see what the new Shiv looks like to find out? ;-)

Hello grumpier.mike and All,

Anyone seen more numbers for just the Mavic CX01 blade portion concept of the Mavic CXR80 tire+rim+blade? .... (tire+rim+blade plot below) .... while designed for tubulars ..... is it there a worthwhile gain for clinchers by smoothing the tire/rim interface?

I don't see the CXR80 listed in the present Mavic wheel lineup .... looks like it was dropped.

https://cycletechreview.com/...s-wheels-disallowed/

Excerpt:

"The UCI, naturally, doesn’t like it and has said no, leaving triathletes and British time triallists the only two-wheeled competitors able to ride the wheels with their blades fitted."









The Bontrager 'wings' tire looks like a good way to get the benefits of a smoother tire/rim interface ...

From Bontrager advertisement:

"Bontrager's R4 Aero Tire is all about making you faster and more efficient. Its 220tpi casing creates less drag and provides a supple road feel you'll love, while the tread minimizes rolling resistance and grips great in the corners. The R4 Aero also features integrated flat-tire protection. Plus, this amazing tire has Bontrager's unique aero wing design that saves you energy mile after mile. In fact, it has been tested to save over three minutes in the bike leg of the Ironman Triathlon! No wonder Keith Bontrager himself calls the R4, "the World's Fastest Tire."

....... but what is the best practice method for smoothing other brand tires tire/rim interface?



One of the home brew methods that have been around for many years is to smooth the tire/rim interface crack with silicone sealant.

Other methods?

Or is the aero gain worth the effort?

---

Cheers, Neal

+1 mph Faster

Wheels look nice. Not sure why a 21 spoke rear, that just screams we want to be proprietary, which screams run the other way.


Can the rims be purchased separate?
Any component weights? (rims /. hubs?)

Weight on the only review so far shows 1416, which is still light, but not sub 1400g. What is your +/- spec on that?

At least for the CLX 64s, the front weight like 695 grams IIRC. I can't remember what the rear was but I think around 850 or so.

---

---

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

Although I'll likely race on TCs with latex, I'm looking forward to trying tubeless with these, especially for off-season work. From a weight and performance perspective, would the Silca valve & tape be better than the stock valve & spoke-hold plugs? I've no experience with either, obviously, but I'm a huge fan of what Josh is doing & would happily support him if there's a performance advantage. Thanks.

I'm a huge Josh fan as well. I actually just sold my pair on eBay and I did use Silca 25mm rim tape on the set and it worked well. I prefer it because it is thinner and a bit easier to get on the tires, but frankly that is one benefit to the Roval, they aren't terribly difficult to get tires on to in the first place.

---

---

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

Thanks again, Tom. I just ordered their tape & valves. Didn't pull the trigger on the $36 balancing kit, though, because I want them to respect me in the morning.

Interesting thing about the balance kit...I don't even need it for my Hed Jets, since the rim extrusion plug opposite the valve hole naturally balances the setup when a tubeless valve is installed...in other words, the lack of balance thing is a full-carbon clincher problem ;-)

---

http://bikeblather.blogspot.com/

Wow, Tom A. Thanks for that. I didn't even think about that. I guess my HED JET Black+ is now really approaching a full carbon clincer weight level without the need for the balancing kit. Just another benefit of the HED JET+

---

---

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

I don't have a balancing kit either. I have the speed valves, speed tape, and Hiro but I do have my eye on some more of their offerings. What I really want is a travel size pump to replace my Lezyne Travel Pump with a more accurate gauge, and a longer hose. I have talked to Josh about it briefly. Hoping he can deliver at some point.

---

---

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

A couple notes on our tubeless set-up (saw you already bought another valve and tape, but addressing for others with the same question):

The valves that are supplied with the rims are built specifically for the rim depth/valve hole - so essentially they are the best possible valve for each wheel to prevent any balancing or sealing issues. Other valves will work, though they're made to be more universal in length and valve hole diameter.

The spoke-hole plugs are comparable in weight to the lightest rim strip on the market, but the team selected this solution from a durability standpoint (no issues with tape peeling, installation, blow through, or heat) and the ability to remove only one plug to address any spoke issues.

I'll try them too for sure. Thanks, Cam.

My $0.02: your best bet is a Specialized Air Compact pump and then a digital gauge that can bleed like this one, or this one if you want to be super super accurate, or you can build you own starting here.

Chris,

As far as I'm aware, Zipp's testing shows stall angles much closer to 15 for firecrest 808s, and 17-18 for NSW 808 wheels. I'm kind of suspect of the data you just put out on that basis. Would you say tire selection has that much of an impact to negatively affect stall angle?

I know I'm not the guy you asked but, from looking at lots of wind tunnel reports I'd say that's a safe guess. Take a look at Flo's interactive chart and select the GP4000S II and the Supersonic (both 23mm). Notice the (dramatic) difference in the stall point.

This is a bit off topic, but is there any rotational power loss from an imbalanced wheel? Now that I think about it, and my coffe is starting to kick in, there would be series of accelerations and deceleration as the point of imbalance moved from the top of the wheel to the bottom and vice versa.

I assume there is a formula that would give force as a function of the mass of the imbalance, distance from the axle, and rotational speed. Would you have a decent reference or know the formula. My knowledge of the problem runs out at F=ma.

Not looking for an argument or to derail the thread, but I strongly disagree with the recommendation for that $300 digital gauge. The other 'gauge' linked was the same air pump as the first link. Since bike tires are relatively low volume, you're going to lose quite a bit of pressure just by attaching the hose. You would have to put an extra 10-20 psi in the tire before you attach that gauge to ultimately get the numbers you want. Maybe even more. Kind of the same concept as attaching a suspension pump to your mt. bike and 'seeing' the pressure a lot lower than where you started; it's due to the hose being filled with air from the tire. While we might all be playing with different definitions of accurate, pumps tend to be more accurate at higher pressures vs. lower pressures so a gauge may not be necessary for road tires. The ST crowd seems to like to go beyond that though. I would recommend the ~$25 SKS airchecker. I have the Topeak Smartgauge D2 as well, but don't like that it doesn't go down to 0.5 psi increments. You can bleed from the SKS with the orange button, but the attachment/removal process only loses ~1.0 psi each time when playing around with low volume tires at 90+ psi. It's easier to do it that way (1 handed) than fart around with a bleed button. Then you (not directly you) have $275 laying around as a down payment on a trainer desk/tray.

I can't comment on the gauge accuracy of the Specialized pump, but my friend has it and I think it's a great option for the size when the Jeep was packed full of our CX crap. I had no idea it was $100 though! I would just throw a few pumps in and then use my gauge, but it was pretty strong for how small it was.

Good point about the hose, I hadn't considered that!

Re Specialized pump: I doubt it's accurate. For me I like how it folds up because I often put it inside my Scicon Aerotech Evolution where space is at a serious premium.

Yeah, it folds up really well! Plus a lot of full size pumps have metal bases (often with sharp edges) that will mess up everything they touch in your vehicle.

Theoretically, yes...but the amount of imbalance would need to be massive for it to be anything appreciable.

A few years back I picked up a cheapo set of "spoke lights" at Costco. These things are a fairly large electronics pods with LEDs and batteries that you attach to the wheel, and as you're riding the LEDs "draw out" a pattern that appears to fill the entire wheel as it rotates. Obviously, putting one of thes devices on a wheel causes a pretty large imbalance. I put them front and rear on my commuter bike to increase nighttime visibility. Occasionally, I would notice the imbalance, like when I "descended" the freeway overpass on the way to work, but it was really only bad if the front and rear happened to be in phase with the imbalance. When that happened, it created a noticeable "fore-aft" surging that wasn't very confidence inspiring, and also probably dissipated energy in my butt and hands.

But, like I said, that was a HUGE imbalance.

---

http://bikeblather.blogspot.com/

Did you mean YUGE?

Bigly :-)

---

http://bikeblather.blogspot.com/

Hello dangle,

We need a pressure measuring device like a durometer to read bicycle tire pressure by pushing on the tire .... like with your thumb ... but accurately ..... might need to be keyed to each tire type to account for sidewall thickness and temperature and ?????? .....

"A durometer gauge or durometer tester is needed to perform a durometer hardness test procedure. Durometer devices determine the surface hardness of many different materials, including polymers and elastomers. Each durometer or hardness tester measures the depth of an indentation in the material caused by a defined force of a given geometric presser foot. The depth of the indentation reflects the hardness of the material. A general distinction is made between static and dynamic methods. In traditional static tests, the test force is applied uniformly with increasing magnitude, while in dynamic testing methods, an instantaneous load is applied."


It would be a more direct measurement of tire deflection where the rubber meets the road instead of an indirect measurement using air pressure and be quick and easy without the loss of air pressure.

---

Cheers, Neal

+1 mph Faster

You guys talked me into it

Just ordered a set from my lbs with 24 turbo cotton tires.

Should be in next week

Did you go with the 50s? The turbo cottons are the best tire out there...you are going to love them especially with some latex tubes!

But running tubeless with the plugs is also a badazz setup

I just picked up a CLX 64 front wheel for my Felt IA. After reading the white paper and the answers to questions from the engineers on this thread it seems clear to me that this should be the most popular wheel in triathlon. Faster, lighter and more then $400 less expensive than an 808 NSW? I'm in. Gonna run a jet disc plus on the rear. I've heard rumors you guys have a disc coming out in a few months but I need one sooner, and $/performance for the Hed is tough to beat.

---

-------------
Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

Circling back around on this topic. Did you ever get a chance to try the spoke-hole plugs? If so were they on the CLX 50 or CLX 64? And lastly, how much do the plugs weigh? Any thoughts on the setup.

---

---

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

can we discuss also braking performance - since in the past Roval used to struggle with it and since both enve and zipp nsw improved their brake track

I'm not the poster to whom you were replying, but I did have the chance to run the spoke-hole plugs on CLX50s for a few thousand miles. They work great! I am sure that I wrote down the weight of them somewhere but I can't find it at the moment; they're lighter than rim tape. (I've used them for Roval MTB wheels, too.)

I run tubeless MTB setups for a long, long time and have had no problem with tape, but I like the weight savings of the plugs.


The worked just find on the road.


As above....thousands of miles testing the CLX50s and no issues with braking. I have ridden Enves over the years and have many, many thousands of miles on Zipps (though only limited riding on wheels with the new Zipp brake track). The CLX50 brake tracks with Swisstop pads were as good or better than any wheel with a carbon brake track I've ridden. Full power with 1 finger is possible.

FWIW, I live at the base of a 5+ mile, 10% mountain pass that I consider to be a good test of power and modulation. The standard Zipp braketrack has never left me wanting for more, so as long as I have that or better I'm happy.

I have tested *mostly* in dry conditions -- no monsoons.

A friend who has more miles on wheels with the Firestrike/NSW-style braketrack than I have has told me braking power exceeds that of the standard Zipp, but they burn up brake pads at a far higher rate.

Rim plugs save about 30-35g per wheel so that 60-70g on a wheelset is actually quite a big difference.

Hello GatorRacer and All,

+1

https://veloplug.com/

---

Cheers, Neal

+1 mph Faster

I bought some second-hand wheels from the ST classifieds that came with veloplugs. Had issues with flats and latex tubes. Switched to Stans rim tape and have been all good. I think there are better ways to save weight...

---

/kj

http://kjmcawesome.tumblr.com/

IIRC Stans tape only weighs about 10-15 grams per wheel so I am not seeing how you would save 30-35g per wheel. And I assume these plugs just are not velo plugs. These plugs are used to seal air coming out, they much be different, but I don't know for sure.

---

---

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

That estimate was vs rim strip...tape isnt quite as much, you're right.

As for the veloplugs, you need to consider the shape of the drop center. A rim needs to be designed to work with the plugs (or plugs with the rim) to make sure the seal is good and consistent. If the drop center shelf is too narrow you can get issue with the plug not seating. The typically "flat" plug has to seal against a curved surface so fit is critical.

Lastly, different rims have different spoke access hole diameters so its not a true 1 size fits all problem even if the supplier says it can handle the specified range. (not doubting veloplugs claims but a plug designed for a specific rim is going to be better!)