AERO brakes

Discuss light weight issues concerning road bikes & parts.
acoggan
Posts: 17
Joined: Thu Dec 22, 2011 8:28 pm

by acoggan

Juanmoretime wrote:Like many things areo brakes need some independent wind tunnel testing to validate claims.


I agree. ;)

Juanmoretime wrote:I would be very curious to see the time difference between the Omega and Simkins.


Using our validated model of the power requirements of cycling (1) and assuming:

1) total (i.e., cyclist + bicycle) mass = 85 kg,
2) coefficient of rolling resistance = 0.004,
3) drivetrain efficiency = 97.5%,
4) air density = 1.185 g/L,
5) CdA = 0.225 m2, and
6) power = 300 W

I calculate that using an Omega instead of a Simkins would save you 1.9 s in a 40 km TT.

With the same assumptions as #1-4 above and assuming:

5) CdA =0.250 m2, and
6) power = 225 W

I calculate that using an Omega instead of a Simkins would save you 7.9 s in a 180 km Ironman bike segment.

1. Martin JC, Milliken DL, Cobb JE, McFadden KL, Coggan AR. Validation of a mathematical model for road cycling power. J Appl Biomech 1998; 14: 276-291.

by Weenie


acoggan
Posts: 17
Joined: Thu Dec 22, 2011 8:28 pm

by acoggan

refthimos wrote:Image


FWIW, I've tested an MRC and a D-A AX (1st and 2nd from left), but have been unable to lay my hands on a Modolo Kronos (3rd from left). I also haven't tested the TRP T925 (far right), but have tested it's cousin, the Tektro R725.

Lastly, I've been in contact w/ Magura again, and even though the RT8TT is still in very short supply they are supposed to be sending me a brake to test.

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Juanmoretime
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Location: Urbana, Illinois

by Juanmoretime

Thank you Andrew and if it has not been done, welcome to Weight Weenies!

I guess the good news is I left some "free speed on the table".
RESIDENT GRUMPY OLD MAN.

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Arky
Posts: 522
Joined: Sun Sep 23, 2007 5:06 am

by Arky

That AX is a work of art!
Last edited by Arky on Thu Jun 21, 2012 6:21 pm, edited 1 time in total.

jrennie
Posts: 496
Joined: Mon Oct 23, 2006 2:56 pm
Location: Reno, NV

by jrennie

I hope andrew can locate a modolo with a rubber cover as I would like to see the test complete. I use one minus the cover and spring guide on the cable adjuster. I'm using cut SS yellow pads and the braking with stingers is great. The lack of pad height adjustment is annoying.

refthimos
Posts: 104
Joined: Fri May 25, 2012 6:02 pm

by refthimos

Cyco wrote:The MRC brakes look a lot like the brakes that Zipp used to ship with the old 2001 frames, though they had a slightly pointier carbon cover on them


Ahhhh yes... how could I forget Zipp's aero brake? (particularly since I sold one just a month ago) For as many things as Zipp has done well over the years, this frankly was not one of them (something I mentioned to the buyer - the Zipp brake went with a Zipp 2001 bike that had Kronos brakes on it).

For those curious, here is a photo:

Image

Also, if folks want to see more photos of the Zipp or Kronos calipers, I have an online photo album here:

http://s42.photobucket.com/albums/e344/refthimos/Zipp2001/

Just to be clear, the bike is sold - I am not trying to sell anything here - so please don't ban me! :-)
EVO Hi-Mod | 9070 Di2 | Rotor 2Inpower | Aeolus TLR 3/5
P5 | 9070 Di2 | Rotor 2Inpower | Aeolus TLR 7
T1 | Power2Max Type S | Rolf Prima FX58/Zipp Super 9 Disc
SuperX Hi-Mod Disc | Sram Red | Power2Max NG

refthimos
Posts: 104
Joined: Fri May 25, 2012 6:02 pm

by refthimos

jrennie wrote:I hope andrew can locate a modolo with a rubber cover as I would like to see the test complete. I use one minus the cover and spring guide on the cable adjuster.


The rubber cover on the Kronos is notoriously fragile and even NOS examples are likely to be cracked/damaged (mine were slightly). While not a scientific answer to your question, I think it is likely that any drag difference would be so small as to be immeasurable.
EVO Hi-Mod | 9070 Di2 | Rotor 2Inpower | Aeolus TLR 3/5
P5 | 9070 Di2 | Rotor 2Inpower | Aeolus TLR 7
T1 | Power2Max Type S | Rolf Prima FX58/Zipp Super 9 Disc
SuperX Hi-Mod Disc | Sram Red | Power2Max NG

llhh
Posts: 78
Joined: Tue Jan 10, 2012 8:10 pm
Location: Estland

by llhh

Isn't the TRP supposed to be mounted on the back of the fork? Seems a bit off to compare with front-facing brakes that the rest are?
Parlee Z1 Super Record / ENVE / Campangolo Bora

BmanX
Posts: 3844
Joined: Thu Nov 10, 2005 5:31 pm

by BmanX

OH this is going to be good. Just wait.
BIG DADDY B FLOW
AERO & LIGHT is RIGHT

Cervelo SLC 5960g/13.13 lbs

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shoopdawoop
Posts: 433
Joined: Thu Dec 22, 2011 12:37 am

by shoopdawoop

Has anyone seen an S-5 with a Tri-Rig brake mounted? I'm just wondering if that rear brake mount type this would block the Omegas cable guide. I really hope not though as I hope to get a set for my bike :thumbup:

BmanX
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Joined: Thu Nov 10, 2005 5:31 pm

by BmanX

Image
BIG DADDY B FLOW
AERO & LIGHT is RIGHT

Cervelo SLC 5960g/13.13 lbs

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shoopdawoop
Posts: 433
Joined: Thu Dec 22, 2011 12:37 am

by shoopdawoop

That looks really good on there! :thumbup:

I'm more worried about the rear brake on the S-5 though. It has a weird mounting bracket that is pretty tight. I would take a picture but that is what broke on my S-5 but I'm just wondering if the brake cable guide will be able to fit.

BmanX
Posts: 3844
Joined: Thu Nov 10, 2005 5:31 pm

by BmanX

Once I get these I will mount them to the SLC but yes I am not sure about the S5 but maybe one day I can help you out with that when I pick on up used.
BIG DADDY B FLOW
AERO & LIGHT is RIGHT

Cervelo SLC 5960g/13.13 lbs

acoggan
Posts: 17
Joined: Thu Dec 22, 2011 8:28 pm

by acoggan

llhh wrote:Isn't the TRP supposed to be mounted on the back of the fork? Seems a bit off to compare with front-facing brakes that the rest are?


I tested the Tektro R725R and T726R models, which (as the designation suggests) are actually rear brakes. By replacing the mounting bolt with a longer one, though, they can (and often have) been used on the front as a PMAB (poor man's aero brake). This is why I thought it was of interest to include them in my sample.

I have not tested any brakes mounted on the rear of the fork, in part because many bikes don't have room for them there and in part because the potential for significant interaction effects between the brake and the tire and/or the brake and the downtube seem (to me) to be much greater. If anybody out there is really interested, though, you might be able to talk me into finding the 1-2 h required to perform such a test.

acoggan
Posts: 17
Joined: Thu Dec 22, 2011 8:28 pm

by acoggan

shoopdawoop wrote:Has anyone seen an S-5 with a Tri-Rig brake mounted? I'm just wondering if that rear brake mount type this would block the Omegas cable guide. I really hope not though as I hope to get a set for my bike :thumbup:


Looking at pics of the S5, it appears that the cable hanger of the brake might hit the seat tube, and even if it doesn't, there might not be enough room for a smooth cable run.

If so, one option might be to use the additional spacers provided to mount the Omega further away from the frame...although I've only tested the effect of the gap on the front, not the back, I doubt it would measurably impact the aerodynamic drag.

by Weenie


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