Delta - Aero Data

Delta Wind Tunnel Report

In February 2019, we took a trip to the San Diego Low-Speed Wind Tunnel for a comprehensive study of Delta. We wanted to see what kind of benefits it has apart from the obvious aesthetic ones. Note that the samples used for testing were raw pre-production samples, and that production samples of Delta feature a much nicer finish, with a glossy black clearcoat exterior, as you can see on the installation page.

Our testing confirmed that Delta offers a substantial aero benefit to both standard bikes and superbikes alike, making it one of the best upgrades on the market. Get yours now!

Executive Summary

Delta + Omni

Full Test Results

Weighted-Average Drag

Weight Set

We tested Delta in a variety of ways, both on the Omni bicycle, as well as our baseline Cervelo P3 test rig, to provide a picture of how Delta would perform both on our radical frame and on a traditional double-diamond frame. Interestingly, the results were extremely consistent. Delta made both bikes faster, to almost the same extent.

Above, we're showing the results on Omni, but they are substantially similar when we tested on the Cervelo P3. The full data for both bikes is available on the next page. In analyzing the data, we compute weighted-average drag figures designed to simulate real-world wind conditions. The weight sets and the raw data are all available for readers to interpret themselves.

In short, Delta makes your bike significantly faster than having no brake at all, and even faster than just running the bare Omega brake which it covers.

Test Rigs + Protocol

TriRig Omni test rig

Cervelo P3 test rig

TriRig Omni test rig

Cervelo P3 test rig

We try to keep things very simple and straightforward when testing aero equipment. Ideally, only one thing is changed between two consecutive runs in the tunnel, in order to isolate the effects of that one change. For these bike-only tests, we ran the wheels and wind at 30mph, and sampled data for 15 seconds at each of 0, 2.5, 5, 7.5, 10, and 15 degrees of yaw. We tested Delta's effects both on our own Omni bicycle, for which Delta was originally designed, and also on the Cervelo P3 test rig we have used in the past, to see if Delta's effects were significantly different on traditional frames compared to our more radical one.

In the end, it appears that Delta has very similar effects regardless of which bicycle it is used on, saving significant drag for both. If anything, our testing might understate the aero benefits Delta provides, since none of our test rigs had exposed cables which Delta can potentially hide.

Both rigs were set up with identical wheels, saddles, drivetrains, cockpits, and positions.

Interpreting the Data

In most cases, the potential benefits of any change on a bicycle must be weighed against its potential drawbacks. In the case of Delta, we are presented with the rare example of an unalloyed good. Delta reduces drag across the entire yaw sweep, cleans up any exposed cables or hardware, and doesn't have any real drawbacks. Both bicycles exhibit significantly less drag with Delta then even with no brake hardware at all! And compared to traditional sidepull brakes, the combination of Omega and Delta saves almost 4 watts! That can translate to almost 0.5 seconds per kilometer of racing, or 90 seconds over an Ironman bike leg.

The data here also corroborates what we learned in our previous studies, that Omni is a faster bike than its best-in-class double-diamond cousin, even when that double-diamond bike is set up with the fastest bars and brakes on the market. But these tests demonstrate that Delta can help narrow that gap, bringing double-diamond performance even closer to that of the Omni. As always, the reader is encouraged to interpret the data for themselves and come to their own conclusions.

Data + Images

Omni + Delta Tests

Omni + Delta Weighted-Average Drag

P3 + Delta Tests

3 + Delta Weighted-Average Drag

Weight Set

Beta control at the LSWT

Knobs at the LSWT

Cervelo P3 Test Rig

TriRig Omni Test Rig

pTriRig Omni Test Rig

TriRig Omni + Sidepull Brake

TriRig Omni Test Rig

Fit Guide

This Guide shows you how to set up your TriRig Omni with the TriRig Alpha One or Alpha X aerobars. This Guide can help you replicate your current bike position, or set up your bike based on numbers from a bike fitter. The Fit Chart below shows the actual X/Y coordinates of your arm pads measured from the bottom bracket. This coordinate is the most important number that bike fitters use to determine your position on a triathlon bike. Be aware that some fitters use a coordinate to the top/back of the pad, rather than the top/center. In that case, you can subtract 44mm from all of the reach numbers in the Fit Chart, which yields the back of pad number. The steps below provide an easy-to-follow system for making sure you have the perfect fit with your Omni.

Step 1: Determine your current fit numbers

What we want is the X/Y coordinate to the top/center of your aerobar pads, measured from the bottom bracket. Most bike fitters can provide this number to you when performing a bike fit (although some provide it to the top/back of the pads rather than top/center). If you already know these numbers, you can skip this step. Otherwise, follow the steps below to determine these numbers for your current bike setup:

1-Place your bicycle up against the corner of a room, with the back tire abutting the wall.

2-Next, measure the vertical distance from the floor to the center of the bottom bracket. We'll call this measurement Floor Offset (FO).

3-Measure the horizontal distance from the wall to the center of the bottom bracket, we'll call this measurement Wall Offset (WO).

4-Measure the vertical distance from the floor to the top of your aerobar pads. This measurement will be Pads-To-Floor (PTF).

5-Measure the horizontal distance from the wall to the center of your aerobar pads. This will be called Pads-To-Wall (PTW).

6-Subtract Floor Offset from Pads-To-Floor (PTF minus FO). This is your Pad Stack.

7-Subtract Wall Offset from Pads-To-Wall (PTW minus WO). This is your Pad Reach.

Step 2: Review Frame Geometry

	Small	Medium	Large
Frame Stack (BB to Headset)	490mm	525mm	560mm
Frame Reach (BB to Headset)	375mm	405mm	435mm
Front Center	560mm	600mm	640mm
Rear Center	400mm	400mm	400mm
Seat Angle	79°	79°	79°
Head Angle	72.5°	72.5°	72.5°
Fork Offset	48mm	48mm	48mm

Step 3: Select Size, then find your position on the chart

The chart below shows the stack and reach information for the TriRig Omni with the included Alpha X aerobar, complete with the number of extension spacers and stem spacers used for each setup. Here's how to use the chart:

1-Use the dropdown box in the upper-right corner of the chart to select a bike size.

2-Find your Stack in the left-hand column of the chart, or the row that most closely matches your stack. Every cell in this row represents a way to set up the Alpha X on your Omni that will produce this stack number.

3-Each cell states the amount of Pad Spacers as well as Stem Spacers to use in order to hit your stack number.

4-In most cases, there will be multiple cells that can hit your stack. The best setup for your position will generally be the one with additional colored cells above AND below your selected cell. These cells represent room to move up or down in the future, merely by adding or removing Pad Spacers, which is generally the easiest way to make a position change.

5-Cells in blue represent a standard setup with the extensions over the bar. Cells in green represent the special undermount position, where the extensions are mounted below the bar.

6-Once you have selected a cell from your Stack row that represents your preferred position, look at the bottom of that column to the Reach section. The three rows of Reach cells show the reach to the center of the pad based on the three different adjustment positions available on the Alpha X arm cups. Select the one that most closely matches your Pad Reach number, and set up your pads/cups accordingly.

7-Note that fit numbers for the Omni w/ Alpha X are measured from the top/center of the headset to the top/center of the pad. All measurements for overmount hardware include the integrated BTA mount.