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 Nocom Vs. M5 Carbon High racer aerodynamics

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T O P I C    R E V I E W
sean costin Posted - 06/30/2011 : 05:18:06
I completed the following test of my M5 Carbon High Racer and my Nocom.
Please let me know if you have any questions or thoughts. Also, If you have similar data on either bike, it would be interesting to see.

Conditions : Dead Calm Northbrook Velodrome 67 deg. F. June 29 2011

Front wheel Trispoke Rear wireless Powertap wheel with disk cover
25.61 mph on 202 Watts Ave.
over .55 miles 1:19 seconds

27.02 mph on 231 Watts ave. over .38 miles 51 seconds

Front Disk and Rear wireless Powertap wheel with Disk cover.

27.53 mph on 201 Watts Ave
over 1.3 miles in 2:50

29.08 mph on 231 Watts Ave. .4 mile 51 seconds

Comparison data
Excerpt from Indiana race at the end of April 2011 with Powertap wheel with no rear disk. Windy conditions
27.12 mph on 200 Watts Ave
5 minutes over 2.26 miles
- bumpy cement velodrome
- this validates the speed of today's test and tells me that the rear disk covers added about .5 mph at 200 Watts.

Summary of speed difference:
1.92 mph faster with the Nocom at 200W
2.06 mph faster with the Nocom at 231 Watts

I like this 200 and 230 watts testing. You can typically hold a very steady pace at 200 for a few minutes to get very good accuracy. At 230 Watts I was having some trouble keep it even. I dont think my average watts on the computer reset with each interval, so I used the current watts to pace myself which was more difficult. I will probably need to download the data between each test next time so that I can be working with average watts at each test. I think we should all try to use the speed at 200 W as a benchmark for testing.

I used the power agent program which allows me to get data by dragging over any section of the graph to get the most representative data and then the program summarizes the performance for just that section.

This test serves as a baseline for future tests for the Nocom Vs. M5 Carbon Hi Racer and set up changes for each.

I hope to do a hill climb test and an acceleration test as well.

The only difference in this test between the two bikes was the cranks, but the M5 had a more aerodyanmic one chain ring crank set than the Nocom with a 2 chain rings on a Rotor Crankset. Both bikes had aerodynamic disks on the chain rings.

Because we are testing at the hub of the rear wheel, this isolates power at the last possible area, therefore this removes any difference in drive train efficiency from the equasion to get accurate aerodynamic data (Speed vs. Power input)

Seat position on the M5 was very laid back. At the rear curve of the seat, the bottom of the support ribs were flush with the frame of the bike. I used an add on Headrest which put my head in a similar position as it is on the Nocom. I have seen other racers lean their heads back further than what I tested, but I did not feel comfortable with that configuration at this point. I used the same helmet for both bikes.

I have no affiliation with M5 or Velokraft or their resellers. I am doing this testing to fulfill my own curiosity and to better understand recumbent aerodyanmics through scientific testing.

It should also be noted that I have had many years to tweak the Nocom aerodynamically. The M5 can similarly be tweaked. The front Trispoke is not as good as a full disk, but handling a 700 disk in windy conditions could be a problem which I would not have with a Nocom.
2 mph would require a lot of tweaking. It is also possible that it is easier to make power on the M5, which will be considered in other tests between the 2 bikes. The M5 is considerably lighter which would be better for climbing and accelerating.


14   L A T E S T    R E P L I E S    (Newest First)
patcoturf Posted - 07/07/2011 : 19:24:14
Aha! Awesome ride...

Thanks for the info.


Upright Mike Posted - 07/07/2011 : 08:32:53
Velokraft NoCom lowracer, carbon fiber frame

Warren's NoCom (circa 2006)

Sean on his NoCom

At full speed (Video)
patcoturf Posted - 07/07/2011 : 08:13:29
Please pardon my ignorance, as I am a relative newcomer to recumbents; what is a Nocom?


John Patterson
Longbikes Slipstream
Speedy Posted - 07/01/2011 : 13:45:01
zero the torque between each test set up is a good idea

the early versions of PowerTap hub most definitely went berserk after 55 mph ... not much use at BM

Sean ... be sure to add air density to your notes, after a few months of testing it will be useful

Larry Lem Posted - 07/01/2011 : 10:56:15
The need to zero the torque in a PowerTap hub is apparent when one coasts and the power reading is not zero. Else, it is fine. The discrepancy/mystery of the PowerTab hub torque and cadence readings versus the power reading is a separate issue.

The dimples on some of the earlier Garneau helmets are also vortex generators.

Larry Lem
Zyzio Posted - 07/01/2011 : 10:23:36
Where is Chung when you need him...

He did mention in one of his numerous Power Tap discussions the need to manually zero the torque between the tests for consistent resuls. Apparently if it is set to "Autozero", "the offset can get reset between tests".

Regarding vortex generators, Garneau has a new TT helmet with a series of vortex generators around the widest part of the helmet, which are supposed to keep the air attached to the helmet tail. I think this is the first application I've seen in bicycle equipment. Another interesting aero tweak is the tuned slot in the blades of Oval Concepts forks, which cleans-up the air flow around the front wheel. They claim it saves 55 seconds per hour at 50 km/hr. & 0.7 seconds in the kilo.

Larry Lem Posted - 06/30/2011 : 20:50:17
I've never gotten the torque and cadence data to correlate with the power data from a PowerTap hub. It is disturbing. The tech folks at Saris had no response for that.

The only response I ever received was that power measurement goes to hell as one approaches 60 mph.

Oh, the other response I got was that they were never going to make a disk brake hub because the electronics were in the way. It seems that they eventually got around that problem.

Larry Lem
sean costin Posted - 06/30/2011 : 18:34:28
I just noticed something odd. Why is Torque so much higher for the M5 than the Nocom?
sean costin Posted - 06/30/2011 : 18:29:23
Powertap Graphs of both complete tests.


sean costin Posted - 06/30/2011 : 17:48:54
Originally posted by Zyzio

Can you please also list the tires used and tire pressures?

Latex tubes (if you did not use them) could improve the rolling resistance a bit.

Will you test the NoCom with the tail fairing at some point?


M5 Front Vittoria Open Corsa EVO CX Approx 120-130 psi
with Perfomance Ultra light tube

Rear Schwalbe Ultremo Aqua 130 Psi with Performance ultra light tube

Schwalbe Stelvio approx, 120-130 psi
Rear Schwalbe Ultremo Aqua 130 Psi with Performance ultra light tube

This Stelvio was a special low RR tire from Hans Van Vugt. However, I really never noticed a difference in performance from the regular 406 Stelvios.

I think the tube in the Stelvio is a Chen Shin. (wish I had better)

sean costin Posted - 06/30/2011 : 17:31:09
Originally posted by randy

27.53mph at 201 watts? My mind is blown.

Randy, this has got to underscore my mediocrity as an athlete, but I've known this for some time. The guys that have the hour record are well beyond my ability.

I think I can get it better (aerodynamically that is). My PHD brother Dan gave me some ideas on generating vorticies that stay attached behind me by using tubericles.

Here is some PR on the science. http://www.whalepower.com/drupal/?q=node/1

I think you are going to see a boat load of this stuff on bikes in the near future.

Also I think the next big thing aside from tubericles will be drag reducing surface textures on narrow objects such as cranks. It was done effectively on skin suits, but tubes, cables... you name it should be considered for texturing.

Randy what kind of speed are you achieving at 200W?


Zyzio Posted - 06/30/2011 : 11:01:43
Using Warren's HPV calculator and assuming same temperature, rolling resistance of 0.0045 for M5 & 0.0048 for the NoCom, the CdA is:

M5 - 0.155

NoCom - 0.120

Zyzio Posted - 06/30/2011 : 10:42:48
Can you please also list the tires used and tire pressures?

Latex tubes (if you did not use them) could improve the rolling resistance a bit.

Will you test the NoCom with the tail fairing at some point?

randy Posted - 06/30/2011 : 06:34:57
27.53mph at 201 watts? My mind is blown.

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