That means that the windspeed is already at max at the brake and the results of the windtunnel measurements for the brake can be used without any corrections?

That's the way we currently interpret it. (Subject to more information as usual, of course.)

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Keep in mind that different tunnels handle the boundary layer problem differently and with varying levels of success. What Damon says about, what I presume is, the LSWT in San Diego may or may not be true about the A2 tunnel in NC or Specialized's tunnel. It is definitely different than the rolling floor tunnels used for some automotive work.

Good point, and yes, that's from LSWT.

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Thank you for giving some insight in windtunnel features. I did not know all that. Is the rolling floor than supposed to roll as fast as the wind such that there is no boundary layer? Marvelous solution.

The rolling floor in a rolling floor tunnel travels the same speed as the air in the tunnel, thereby eliminating any boundary layers. It comes with a host of problems in actually measuring the forces on the vehicle though, among other things. Not that they aren't solvable....but it isn't a magic pill.

For some cool pictures look up the Windshear Tunnel in NC. Most scale car tunnels are rolling road as well, but there they just hang the model by a stinger and call it done. One of the reasons that scale models still have a place in most race car programs....though CFD is eating into that.

thanks guys - as always you come up with all the answers!

Hi guys.

New (used) P5-6 owner here.. Awesome bike :) got two questions I was hoping some of you would know something about.. One of the magura rt8 brake levers have some "wiggleroom" or "dead space". This is the lever itself and not something related to lack of brake fluid or air in the system. Going fast over bumps etc. you can actually hear the lever "moving some". Is there a easy fix for this? Couldn't find anything googling-around.

Last but not least, pads.. Is CeeGees discontinued or something? I'm unable to pay for a pair of new pads from them.. Tips for other pads that might be a little more comfortable than the very thin stock ones?

Thanks a million :)

Thanks very much for posting.
I have taken into account the effect of the boundary layer in my thread on wheels:

http://forum.slowtwitch.com/...ring=theory#p6308387 (see post #1)

which I called the "Mississippi-effect". However, this effect could be very minimal since Damon mentioned that the boundary layer is only a couple of cm.

In my opinion you are going about your discussion on wheels the wrong way. You are trying to explain why the data isn't good with theory as opposed to trying to explain deficiencies in your data and the way it matches up with theory.

For example if you are interested in bicycle aerodynamics and the study of it in wind tunnels you should preform 2 sets of tests.

Test A) Go out and perform a repeatable chung test of your equipment and position and get a CDA for that setup. Concentrate on repeating that data and minimizing your error window.

Test B) Take that same setup to a wind tunnel and attempt to measure the CDA in the tunnel for that setup.

Do they match? If they do great! A windtunnel is a repeatable instrument to test aerodynamics of a bicycle and it's parts within your margin of error!! You are done, go home have a beer.

Do they not match....shucks....pull out the white board and start doing free body diagrams and equations to see if you can come up w/ the math that makes up the differences. Then once you have come up with that math, derive experiments to prove the phenomenon you have shown to be the difference are actually the difference. Preform those experiments and learn some more. Rinse and Repeat. Spend a career doing this or get your PhD. Spend nights not sleeping due to night terrors about dissertations....when that's all done decide whether you are the type of person that insists on being referred to as "Dr." or not.

Coming up w/ the theory before you have the data is a kind of mental self pleasuring that doesn't really get you anywhere.

The reason why I came up with the discussion of wheels in that thread is that there were dissenting results/opinions of the difference in drag between discs and spoke wheels. Some windtunnel tests had quite small differences and testet a 808 e.g. having the same drag as a disc (this was in a "Tour" windtunneltest a couple of years ago but that is a German magazin). I know of people who posted fieldtests they did, where always a siginificant advantage of a disc compared to a spokewheel resulted. Clearly discs are widely used, also amongst professionals.

And: There are dissenting opinions about the concept of "rotational energy", whether that is measured in a windtunnel or not.

That's how I came to my theoretical interpretation about what happens to a wheel in a windtunnel. Most important is here that part of the rotational energy is measured in a windtunnel by the horizontal scales, part is not.

But this has all nothing to do with the P5.

Another magura rt8 related question. I lost the brake pad spacers, and I couldn't find those at magura site or the specs of the spacer so I can try to buy them at local shops.

Does anyone know where I can get them online or the specs of the spacers. Such as M2,M3 and the width etc...

Thank you very much for your time and help

When I remember well the pads are Shimano ( which is Sram compatible). I remember that, because the receiving geometry in the calipers do not allow Campagnolo pads.
To be sure it should be mentioned in Magura manuals.

Hi thanks for the help, so I can just buy shiamano brake shoe and use the spacers there right?

Probably. Do not remember whether Magura had its own spacers to use with the shimano shoe. I think you can just use the shimano parts , that should fit.

hi guys

a friend of mine is buying my frameset and wants to know what brake options he has. other than tri rig, what other brakes are people using? front and rear please (he doesnt want magura)

thanks,

Hello timujin and All,

Why not Magura hydraulic?

Clean aero profile .....

Hydraulic modulation ..... and stopping power .....

Simple .....

Can be retrofited ........ on most bikes ......

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Cheers, Neal

+1 mph Faster

I'm with Neal on this. Why in the world does he not want those? They're the best brakes I have ever used by far. They also take all of 2 minutes to bleed compared to running new internal cables. There is seriously nothing to not love about the brakes.

I asked for options guys, not a argument for magura.....

Hello.
I need to change my arm pads of my 3T aduro.
There are another options? by changing the arm cup too

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Cervelo P5d and R5 Owner

I use D2Z cradles and poles...

.

It is possible to show?

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Cervelo P5d and R5 Owner

Here you go

https://flic.kr/p/Y25mHW

Should I Stay or Should I Go 🎶 Should I build my P5 without a fitter on-site?

Hey guys. Before I start, let me give you a bit of context:

• Long-time road bike owner, this is my first tri-specific bike
• I got a new P5-six frameset (2014) on a closeout deal while on my last day in Miami
• Brought the bike in its own box over to Paraguay, where I live and it’s sitting in my living room
• This is a small country so there’s only two or three people who do fitting and they do it “by eye”, no retul, no nothing, and *none* of them have experience on tri bikes although they told me “sure, I mean, it’s very similar” (…)
• There is however a certified Retul fitter from country next door who comes and goes from Brazil, every 6 months, and his next visit is in December.

That’s the status quo.

Because I would have to cut the fork in order to install the aduro bars, and later, run the Magura cables through them, the authorized Cervelo shop I got it from said a fitting should be done while/during building the bike, to avoid having to cutting the fork too short, and or, having to remove spacers and having to redo/bleed the brakes, but, as I explained, I don’t have a proper fitting in sight for, at least not the next 45 days, neither do I have an old tri bar sitting around that I could use with a regular stem for the time being.

Quite the conundrum, imma right?

What would you guys do?

1. Wait 45 days until the certified fitter comes?
2. Add every spacer available, cut the fork, train with the bike, get to know it and then redo the cables with the fitter on-site?

FWIW, bike would be a Di2 build so at least I would only have to deal with brake lines for the most part.

One way is to cut a slit in the back of spacers... end closest to you if sat on the bike ...so the cable slides out... you can search on here and find it...