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.