Wind Tunnel Results & Raw Data

Aero Test: Premier Bike Tactical

Wind Tunnel Tests of PremierBike "1.0" Tactical TT/Triathlon Bike.

Author:

18400 Avalon Blvd. Carson, CA 90746 855-243-8376

Prologue:

The following are results from aerodynamic testing of the Premier Bike "1.0" Tactical bicycle utilizing wind tunnel testing. The tests were overseen by ERO Sports to insure both accuracy of the tests and the reported results. ERO Sports was present for all testing. Premier Bike paid for use of the wind tunnel testing, and a consultation fee to ERO Sports.

Facilities/Technologies:

San Diego Wind Tunnel (San Diego, Ca.)

Also known as the Low Speed Wind Tunnel (LSWT), The San Diego Wind Tunnel has been in operation since 1947. Used by aerospace to develop some of the most advanced planes and spacecraft in history, the tunnel has also played a huge role in cycling aerodynamics as its large test section, smooth airflow, and uniform velocity all equate to some of the best data collection available. Wind tunnels provide important yaw data.

VELO Sports Center (Carson, Ca.)

The only international level velodrome in the United States, VELO Sports Center is home to both ERO Sports and the Alphamantis Track Aero System (TAS), which provides real-time aerodynamic testing. TAS calculates CdA in real-time as an athlete rides a bicycle on the velodrome. This allows the interaction between a moving bike and rider to be re- introduced into the measurement of CdA. This interaction is largely removed during testing in the wind tunnel.

Bikes Tested

The Tactical was tested against the Felt IA10, a bike with s similar MSRP. Both bikes we setup up as close as possible for saddle position and angle, and pad stack and reach. The Felt was not a completely stock setup as noted below, and crank length was slightly different between the Tactical and IA10. Saddle height and pad stack were normalized for the difference in crank length during both wind tunnel testing.

Bike	Premier Bike "1.0" Tactical	Felt IA10
Size	Med	54cm
Base Bar	Tactical	Zipp Vuka Aluminum
Aero Bar	Tactical	Profile Design ZBS
Front Brake	Tactical	TriRig OmegaX
Rear Brake	Tactical	TriRig OmegaX
Saddle	Cobb VFlow	Cobb VFlow
Groupset	Shimano Ultegra Di2	Shimano Ultegra Di2
Crankset	Shimano Ultegra 170mm	Shimano Ultegra 165mm
Rear Wheel	Premier Disk	Premier Disk
Front Wheel	ENVE 6.7	ENVE 6.7

Aero Bar Setup Specifics:

Pad Stack: 615

Pad Reach: 490

Extension Length: 370mm

Wind Tunnel Results

The following are data presented by the San Diego Wind Tunnel without alteration.

Premier "1.0" Tactical vs. Felt IA10

Drag in Grams @ 30 mph

Angle	Premier "1.0" Tactical	Felt IA10	Differential
-15	429	335	94
-12.5	464	395	69
-10	510	474	36
-7.5	551	572	-21
-5	606	629	-23
-2.5	647	663	-16
0	656	678	-22
2.5	654	676	-22
5	607	630	-23
7.5	523	538	-15
10	462	422	40
12.5	402	337	65
15	364	300	64

Premier Bike - Average Drag (grams) -10 to 10 degrees: 579, Average -15 to 15 degrees: 529

Felt IA10 – Average Drag (grams) -10 to 10 degrees: 587, Average -15 to 15: 512

As seen on the above charts, the Premier "1.0" Tactical performs well relative to the IA10 when yaw is 7.5 degrees or less averaging just over 20 grams less drag. When yaw increases, the IA10 performs better from 10 – 15 degrees of yaw with an average of approximately 61 grams of drag.

In regards to lower yaw angles, previous tests on the IA10 show that the TriRig Omega X brake reduces drag significantly over the OEM brake. Drag reduction was measured at approx. 6 watts, or just over 30 grams of savings over the Vision OEM brake, which is significant to say the least.

CdA @ 30mph

Angle	Premier Tactical	Felt IA10
-15	0.0388	0.0303
-12.5	0.0420	0.0357
-10	0.0462	0.0429
-7.5	0.0499	0.0517
-5	0.0549	0.0570
-2.5	0.0585	0.0601
0	0.0595	0.0614
2.5	0.0592	0.0612
5	0.0550	0.0571
7.5	0.0474	0.0488
10	0.0419	0.0382
12.5	0.0364	0.0305
15	0.0329	0.0271

"1.0" Tactical 1X Drivetrain Setup vs Baseline

The "1.0" Tactical is designed to have both a traditional 2X Drivetrain chain ring setup, and a 1X Drivetrain chain ring setup. The small chain ring, front derailleur, and front derailleur mount were all removed for this test.

Drag in Grams @ 30mph

Angle	Premier "1.0" Tactical 2X	Premier "1.0" Tactical 1X	Differential
-15	429	371	58
-12.5	464	417	47
-10	510	472	38
-7.5	551	527	24
-5	606	595	11
-2.5	647	640	7
0	656	641	15
2.5	654	637	17
5	607	593	14
7.5	523	515	8
10	462	460	2
12.5	402	384	18
15	364	363	1

There is limited data publicly available for the aerodynamic differences a 1X Drivetrain offers over a traditional 2X Drivetrain. To be clear, a 1X Drivetrain setup is referring to a single chainring on the drive side crank arm with no front derailleur on the bike; a 2X Drivetrain is a traditional double chainring on the drive side with a front derailleur. The results are interesting as there’s a small reduction in drag at yaw angles below 7.5, but quite clearly a significant reduction in drag on the non-drive side of the bike at higher yaw angles. It’s speculative, but not overly so, to presume this reduction at higher yaw is due to the missing smaller chainring, as it’s exposure is significant on the non-drive side at higher yaw angles. More tests on different bike models and drivetrain setups would be warranted to come to a more decisive conclusion. Also, it should be noted a rider would likely influence these numbers as the movement of legs, crank, shoes, pedals, etc. would all alter the airflow through the drivetrain area. Still, the results are worthy of further discussion and testing.

Storage Options

Besides the rear-mounted storage box, both downtube and seat tube storage boxes were tested as well.

The additional pieces were fairly aero neutral.

Drag at 20mph

There were interesting results for the Premier "1.0" Tactical when tested at 20mph. The majority of wind tunnel aero tests are conducted at 30mph, yet the average speed of triathletes, and the majority of Time Trialists, is well below that speed. The question is should bikes be tested at lower speeds? The 20mph results of the Tactical may lead to some interesting discussion.

As is indicated by the results, the "1.0" Tactical effectively stalled at yaw angles at and above 7.5 degrees at a speed of 20mph. The San Diego Wind Tunnel engineers were not at all surprised by the results indicating the drag numbers above were quite common when testing bikes at 20mph. If true, should more bikes be tested at 20mph? This is a speed more common to most triathletes, so are high yaw drag results inaccurate at 30mph for the majority of athletes who ride aero bikes?

Of course, Relative Velocity would be most important in this discussion. Relative Velocity is the combination of the rider’s speed combined with wind speed. For instance, and rider going 15 mph into a direct 10 mph headwind would have a Relative Velocity of 25mph.

VELODROME TESTING RESULTS

Track Aero System Testing

Testing with the Track Aero System was conducted on 12-07-2016 at VELO Sports Center in Carson, Ca. The configuration of both the Tactical and IA10 were identical to the testing conducted at the San Diego Wind Tunnel noted above.

The rider for all testing was, Ian Murray. Two runs were conducted on each bike; the results were consistent enough not to warrant further head-to-head testing. Other configurations were also conducted and the results are noted below.

Head-to Head: Premier Tactical vs Felt IA10

Low yaw performance, as indicated by the previous wind tunnel results, indicated the Tactical would show a lower overall CdA than the IA10. The data from the TAS tests confirmed the prediction.

CdA

Bike / Run #	.CdA
Tactical Run #1	.2965
IA10 Run #1	.3068
Tactical Run #2	.2934
IA10 Run #2	.3090

Tactical Avg CdA	.2949
IA10 Avg CdA	.3079

Watts Saved

Tactical avg CdA vs. IA10 avg CdA: 10.7 watts

The wattage savings are significantly higher from velodrome testing vs wind tunnel, which predicted approx. a 3.8 watt advantage for the Tactical. Why the discrepancy? A simple explanation might be that, with a rider aboard, the Tactical performed better than with no rider; however, there’s another possible explanation. Assumed drivetrain efficiency for the TAS is .98. The Tactical, though, was equipped with Premier’s Optimized Chain, which significantly reduces drivetrain resistance by an estimated 4 watts. This would account for the some of the difference in “drag savings” between the wind tunnel results and those obtained from the TAS testing as the IA10 was equipped with a regular, non-optimized, Shimano 11 speed chain. The TAS would see the difference not as a difference in drivetrain efficiency, but as a drag reduction. The Optimized Chain comes as standard equipment for the Tactical, so it’s use during testing is justified if not necessary.

Predicted Time Savings

Based on avg CdA from all runs, and an average power of 250 watts, the following are estimated time savings for the Tactical vs the IA10:

90K/56mi = 1.93 minutes

180K/112mi = 3.86 minutes

Additional Test Results

Profile Design FC35

The front hydration unit was set up as low as possible between the aero bar extensions, and moved as far back as possible towards the head tube.

CdA Without FC35	CdA with FC35	Watts Saved	Time Saved (180K)
.2949 (avg)	.2910	3.2	1.18 minutes

The drag reduction, based on previous testing, is to be expected from the FC35 when mounted on the extensions in this fashion. The difference between the wind tunnel (no rider) and TAS results is significant, and shows testing hydration systems without a rider does not provide reliable data.

Conclusion

The Premier Tactical bike independently tested very well at low yaw angles compared to the Felt IA10. Despite the IA10 having TriRig Omega X brakes, which previous tests show provide a significant drag reduction at low yaw angles, the Tactical still showed lower drag in both the wind tunnel and during velodrome aero testing with TAS.

Raw Data