aero rear brake question

Nov 30, 15 21:47

Post #1 of 15 (3957 views)

As I'm nearing officially being a senior, I'm a bit reticent to spend a bucket on a new tri-bike.
I own an older papaya colored P3 aluminum that has served me well since I bought it used nearly 7 years ago. I've been in the process of some modest upgrades, like flat (instead of upturned) basebars, a Campy/Tektro center pull front brake to go with my old 404s and a wheel cover. I've also tried to move the cables around so that they are mostly out of the wind, or in front of the head tube. I was pondering the rear brake and wondering if any change to the rear brake, from the standard Ultegra would make any difference? Any thoughts or data on this?

Yes, I got fitted by Dan (with John Cobb kibitzing), so I don't think that needs too much work. I've kept the numbers the same.

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Re: aero rear brake question [docfuel] [ In reply to ]

Nov 30, 15 23:06

Post #2 of 15 (3930 views)

From Cervelo's S5 release

http://www.bikerumor.com/2014/08/27/eb14-cervelo-ups-the-aero-road-ante-again-with-a-new-s5-plus-updated-rca/#more-84774

Quote:

Cerv�lo establishes a set of design priorities as they develop each of their bike lines, and with the S-series it goes: 1. Aerodynamics, 2. Stiffness, 3. Weight, then 4. System Thinking. One of the System Thinking approaches applies to aerodynamics, so through CFD Cerv�lo studied the impacts of individual bike elements on the total aero drag of a road bike with its rider. The numbers revealed key elements that had major effects, and these were items where they dove into more deeply to minimize drag:

1% � seatpost
2% � rear brake
3% � front brakw
5% � rear wheel
9% � drivetrain
9% � bottle
9% � fork
16% � frame
16% � front wheel
30% � handlebar

So it's pretty far down there in terms of aero importance.

Re: aero rear brake question [docfuel] [ In reply to ]

Dec 1, 15 5:16

Post #3 of 15 (3874 views)

Get the drill out and get the cables fully out of the wind!!

http://forum.slowtwitch.com/...post=5518731#5518731

Personally don't see much benefit in putting on an aero rear brake (and this coming from somebody who would take a drill to a carbon frame).

Re: aero rear brake question [knighty76] [ In reply to ]

Dec 1, 15 6:39

Post #4 of 15 (3825 views)

I have my EE brakes on the rear and Omega's on the front which has been an amazing brake set up BUT I did buy two more aero brakes on Black Friday so I might be putting the new Omega X on the front of each bike and the old Omega's on the back.

EE will go on another build.

Re: aero rear brake question [docfuel] [ In reply to ]

Dec 1, 15 6:41

Post #5 of 15 (3823 views)

Get rid of the Campy/Tektro center pull front brake and try to get the Omega's. I had the brakes that you are talking about and still have them in a box somewhere and that is where they should stay.

Re: aero rear brake question [knighty76] [ In reply to ]

Dec 1, 15 6:52

Post #6 of 15 (3810 views)

I've thought about that, but with the old P3 Aluminum, I'd not only have to drill the top tube all the way through, I'd have to drill the down tube as well. There is no extra room in that little head tube. I've considered buying an older P2C or P3C and drilling it, but that's not in my budget.

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Re: aero rear brake question [BMANX] [ In reply to ]

Dec 1, 15 6:56

Post #7 of 15 (3805 views)

BMANX wrote:

I have my EE brakes on the rear and Omega's on the front which has been an amazing brake set up BUT I did buy two more aero brakes on Black Friday so I might be putting the new Omega X on the front of each bike and the old Omega's on the back.

EE will go on another build.

The EE sound interesting, but I see that they are pricier than the TriRig.

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Re: aero rear brake question [BeeSeeBee] [ In reply to ]

Dec 1, 15 7:02

Post #8 of 15 (3798 views)

I've done the all of the highest ones, except aero crankset, (big budget item) so that 2% might be worth something. I've thought about John Cobb's aerobrake conversion--not sure that's worth the effort.

I'm curious if a Torhans 30 might smooth out the flow over the cables that I've pulled around in front of the head tube. All cables from there are pretty straight and horizontal. I currently have a BTA set up.

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Re: aero rear brake question [docfuel] [ In reply to ]

Dec 1, 15 7:14

Post #9 of 15 (3783 views)

I would not do that on an aluminium frame BUT you can be creative with the cable routing and which housings you use.

This is my road bike set up.

My old dual had the cables pinched behind the stem and the rear cable like my road bike

Re: aero rear brake question [BMANX] [ In reply to ]

Dec 1, 15 10:14

Post #10 of 15 (3740 views)

I, perhaps mistakenly, thought that having vertical cable housing that was not in front of the head tube, where the airfoils behind could straighten the turbulent flow, might create more drag. So, I pinched all of mine together in front of the headtube so that the rest of the cable runs are horizontal and close to the head tube. I frankly don't know which is the better solution, but I remember John Cobb saying that a brake behind the fork created more drag than a brake in front of the fork, if the cables are out of the wind, because the airfoil of the fork would smooth the air flow. I might be misremembering this.

Anyone?

(I also don't know how to post photos here.)

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Re: aero rear brake question [docfuel] [ In reply to ]

Dec 24, 15 23:22

Post #11 of 15 (3509 views)

Should try OmegaX brakes for the rear....

I have not tested this setup in the wind tunnel nor analysed in CFD, but my intuition says the following: At cross wind yaw angles, aero bakes could work better in conjunction with the rear aero wheel. Basically smooths the flow over the rear wheel thereby making the wheel work better aerodynamically

Adi Prabakar

Re: aero rear brake question [docfuel] [ In reply to ]

Dec 25, 15 6:44

Post #12 of 15 (3434 views)

I recently replaced my Red & White P3AL with a new P2 and built it like the TriRig version and added wider track wheels. The result... A much more comfortable ride and faster than I imagined. Maybe the old P3AL was flat "worn out"?? I'm 51, so don't rule out a new frame.... One of the best purchases I've ever made! .. What the heck? It's Christmas. Go for it!

Re: aero rear brake question [docfuel] [ In reply to ]

Dec 25, 15 6:50

Post #13 of 15 (3431 views)

To answer your original question... I did only purchase the TriRig front brake initially, but I bought one for the rear on Black Friday.. Not for any significant aero gains, but because this bike is badass and deserving of it :)

Re: aero rear brake question [adi] [ In reply to ]

Dec 25, 15 7:18

Post #14 of 15 (3423 views)

If I get a TriRig, it will go on the front, I suspect.

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Re: aero rear brake question [trigeorge] [ In reply to ]

Dec 25, 15 7:20

Post #15 of 15 (3422 views)

I'm 64, so I'm having a hard time justifying a new bike, but I would love a new P2, or an old P4 for that matter. Anyone selling a 58cm P4?

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

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