8bits

Is there any annoyances of running a front clincher and a back tubular wheel? People often tend to say how tubular feels different than clincher and that got me thinking if this difference would impact on the ride.

I'm currently running with a pair of Mavic's Ellipse and I'm thinking about buying a back FFWD disc for race events.

David Broon 

You're overthinking it.

carleton

+1


8Bits,

If you want more aero benefits, buy an aero FRONT wheel before the disc. The front wheel provides much more aero benefit than the rear. This is why you'll often see elite racers use their aero fronts during warmup jumps to get max speed but not have bother installing their disc yet as well as saving wear on the nice tires:



So, to put it plainly, a Disc + Ellipse front won't make you faster. It will help with standing starts if you are strong enough to twist the Ellipse rear spokes, though.

I would suggest that you buy something like:

- Zipp 404 front
- Zipp 808 front
- ...or similar quality wheels from other manufacturers


Of all of the aero equipment that you choose to use (skinsuit, aero helmet, aero mass start helmet, shoe booties, aero front wheel, rear disc, aero frame, aero bike fitting, etc...), the disc has the lowest bang-for-your-buck in terms of performance. Get the disc to fine-tune things after you've invested in everything else.

8bits

Thanks for the replies guys, and I was thinking it was the other way Carleton, thanks for the heads up

carleton

My first aero wheel was a disc. I felt faster (but I wasn't).

FFWD makes some good wheels. They have 5 spoke and 808 type track front wheels, too.

If you can borrow an aero front wheel for a few laps and maybe a high-speed effort, you'll feel the difference immediately.

If you are a lighter rider, then 808 type rim depth (80mm) might be too much as you will fight the wind a lot. 404 (40mm) is fine. 100mm is waaaaay too much.

carleton

Also, regarding tires:

There exist some clincher tires called "open tubular" which have better casings and feel like tubular tires. Basically they cut a tubular and give it a bead to fit in a rim. They cost more, but feel really good and can be pumped to higher pressures like tubular.

8bits

yeah I saw some of those made by vittoria, they seem nice but can they really be pumped to 120+?

carleton

Yup. Some Vredstein tires are rated to 160psi. Conti Supersonics are rated to 140psi I think.

chas58

And the Mavic ellipse Rim is rated at 140psi. People do split rims sometimes when they go too far.

wens

Anybody know what the OEM wheels for this year's Giant Omnium are rated to? I'm guessing I'm going to have to contact Giant to figure it out.

Racer Ex 

I'm not sure where you came up with this, but holy smokes is it wrong.

Rider position is the biggest factor.

You can go backwards with the wrong skin suit or "aero" helmet. There are only a couple of booties out there that provide any advantage at all, and that's provided they fit right. Even then it's pretty tiny. "Aero" frame vs. rear disc depends on the frame, the disc, and the yaw angle of the wind. And what you're using as a baseline.

You are correct in that the front wheel has a bigger impact than the rear. Also correct on the clincher vs. tubular thing, as far as feel it's a complete non issue on a velodrome. Personally I wouldn't ride clinchers on anything beyond a soft banked 333, but's that mostly because a tubular tends not to blow out as dramatically as a clincher, and they provide a bit more margin of safety at higher pressures. For whatever reasons most of the bang/crash events I've seen on 250's have been clinchers.

Just an FYI I've got probably 60+ hours at various tunnels and aero testing facilities, along with access to a lot of unpublished data from the same, and a ton of field testing hours. And more than a few pursuit/TT records and titles, both my own and from people I coach and have helped set up. There are a few things that are pretty inarguable when it comes to aero stuff, and a lot of things where the answer is "maybe, you need to test". See above.

carleton

Tell me how using a disc + Ellipse combo will make 8bits faster than using the Ellipse rear + Ellipse front that he already had?

The Ellipse rear is already faster than standard spoked wheels with 20 bladed spokes.

Racer Ex 

I have no idea what a "standard" spoked wheel is. I'm sure the Ellipse is better than some wheels and worse than others.

Pretty much any disc will produce less drag both from an aerodynamic standpoint and from a watts to drive standpoint in all conditions compared to the Ellipse, which is not even close to the fastest spoked wheel out there.

Depending on the yaw angle of the wind and the disc, you can actually produce negative drag with a disc. Never see that with a spoked wheel.

Spoked wheels produce a lot of turbulence (which produces drag), all other things being equal (shape, diameter, hub, tire) the less spokes, the taller the rim the less turbulence, the less drag. They also require watts to overcome the drag of the spokes. Less spokes, better shaped spokes, less "mechanical" watts required. A disc requires zero watts to overcome spoke drag, and is essentially a spokeless super tall rim.

That's pretty much the "Intro" primer.

I'm not sure where you're getting your information, but it's way wrong, which is surprising because normally your info is pretty good.

carleton

A standard spoked wheel is a 32h rim with round spokes, standard Velocity type training wheels that come stock on many bikes. Bladed spokes are an upgrade.

I've owned just about every popular track wheel combination available (except for Specialized Trispokes), including Ellipse 20 flat spokes front/rear, 404 front/rear, 808 front/rear, 1080 front/rear (borrowed), 900 disc, Io/Comete, 32 (round) spoke front/rear, 36 (round) spoke front/rear, Campy Vento front (same as Shamal but with road hub), etc... but I've never been in a wind tunnel.

The Mavic Ellipse are faster than you would think. I think they are, by far, the fastest training wheelset available. In terms of rim depth and spoke type, the Ellipse is very similar to the Campagnolo Shamal 16 bladed spoke front wheel which actually tested as fast as the Zipp 404.




I do agree that the disc will be somewhat faster, but I should clarify that my point is that it will not be significantly faster, and certainly not worth the $1,000+ (MSRP) expense when the other items listed are not in play yet. That money would be better spent on a front wheel where gains will be more significant.

carleton

To clarify, I define "training wheelest" as a clincher wheelset that is similar to those that come on low to mid-range complete track bikes. Very few complete track bikes come with tubular training wheels. Only the Bianchi Pista Concept complete comes to mind as one that came with tubular training wheels back in 2006 or so. But, in 2004-2005, that bike came with Mavic Ellipse clinchers as the stock wheelset.

Racer Ex 

You didn't, which would indicate that you don't know what the actual numbers are. So now define "somewhat"

Define significantly. Actually define it in a watts @30 MPH per dollar number, then we can discuss where his best value would be. What if he could get an older Zipp tubular disc for $300-400? What would be the "worth"? Would it be better than spending money on a $300 aero helmet that didn't work?

I figured this (somewhat/significantly/worth) would be the next comment...because these things always devolve into subjective vs. objective measurement when folks put out bad info and are corrected. I'm not trying to bust your balls but there's no such thing as "somewhat" and "significantly" on any of the test data I've produce or my athletes have produced. There's a drag at a wind speed at a yaw angle under "X" conditions (say, mounted in a P3).

Owning a lot of different wheelsets gives you a lot of subjective opinion and some objective data all of which has value. Along with the opportunity to do comparative testing. If you haven't done that testing (and done it correctly) you really have no idea how something performs aerodynamically unless you've got quality data from someone else's testing.

As I said, I'm really not trying to bust your balls but I am trying to correct some bad info and assumptions.

I've worked with Ketchell, Cobb, Giraud, and some other pretty big brains. As I noted above, they'd agree there are a few things that you can say with certainty when it comes to this stuff. Other stuff will surprise you. You want an example? Which of these four wheels would be fastest in the tunnel at 0/2/4/6 degrees yaw? Now tell me the order from highest to lowest CdA on the track:



My wheels, run at the A & M tunnel and at the aEro facility at HDC.

carleton

You win.

Racer Ex 

Seriously? Where's my flippin trophy girl then?

Actually you win because I'm handing out info that cost me and my athletes a lot of time and money. It can save you a lot of time and money and make you go faster.

You really ought to take a shot at the wheel test. You'd learn something of value. The results are pretty interesting.

carleton

My guess: The front disc is fastest on the track. The Tri spoke is fastest in the wind tunnel.

Racer Ex 

Half a cigar. Actually a quarter because you didn't say which disc

Here's where it got interesting (little of this I would have predicted BTW).

In the tunnel from 0-4 deg yaw it went Stinger 9, Corima Disc, Hed 3, Zipp Disc. At 6 degrees the Corima and S9 were tied, then H3, then Zipp disc. Max spread was around 11w. The Stinger pretty much kicked ass.

The Corima and Zipp discs were identical in dimension, slight difference in hub but not much. Both ran 23c tubulars. But different tires. 11w difference. That's a big training block for most folks.

At the track, where everything is measured (mech watts, friction, aero resistance, Crr) to come up with CdA the Corima kicked ass, then the Zipp, then the H3. The Stinger? DFL.

18 spokes vs. 3 spokes vs. no spokes. Same tire pressures, all the barometric corrections, Etc

Changing the tire to match the disc thickness of the Corima made the differentiation even greater. Same tire on the Zipp and Corima and any differential was noise.

You were spot on when you said the front wheel>rear wheel. But the rear wheel sees a lot of dirty air and a disc does a much better job of smoothing that out than a spoked wheel. Both need to be spun and spokes mean more drag (longer spokes mean even more drag). And where it sees clean air it's nothing but good stuff. It's going to change from frame to frame but the dollars to watts ratio for an old tubular Zipp is pretty darn good.

There's a really small reference base out there; most people read the few pieces that are out there and take it as gospel. We tested x helmet against y helmet and x won sort of thing. There you go.

But try testing x helmet against y helmet and it gets flipped. Have the test person drop their head and things change again.

Which is why if you can get a slam dunk improvement you take it. Rear disc is one of those. Deeper, lower spoke count front (or H3) > Mavic. In your face!

The right tire...big. How and what events you ride matter too. The difference between a rear disc and that Mavic wheel is going to spread out as you speed up.

There's a bunch of other stuff that comes into play...wind, maneuverability, stiffness...it's why I wake up in the middle of the night and have a 1000 Ebay transactions.

The more you know,the less you know. Until you know.

carleton

Nice! Thanks for the info. I'm sure that that is just the tip of the iceberg!

Hida Yanra

well then - I'll be over here hastily scribbling notes.

wens

I think I'm just going to use the bookmark function ...

And spend the winter keeping an eye on ebay for a disc that can accept a track axel.