• Max Jenkins: Aero Testing at Hellyer Velodrome

    by  • October 11, 2013 • too random

    Hellyer Aero Testing Permit: #13126

    To reserve a testing session – email: HellyerAero(at)gmail.com

    What is it?

    Come lower your drag numbers and optimize your position. Aerodynamic drag is often over 90% of the forces working against a rider. If you can lower your drag you will go faster with the same effort. It doesn’t matter if you are a time trialist, a triathelete, or a road racer who likes to attack and ride in the wind. Track field testing has been a staple of the Pros for years and here is your chance to join in for a bargain.

    Pricing

    -One session cost $120
    -Two sessions cost $100. Sign up for two days or bring a friend, save some money.
    -Three or more sessions are $80 each. Interested in having your whole team tested? Get big discounts if you have your team mates come.
    -Finally, if you need help making the recommended changes to your bike fit we will gladly provide you with mechanical assistance for $30.

    Dates

    Please check the calendar at ridethetrack.com. The plan is for weekly Saturdays (as the calendar permits), noon until we’re done (3ish), weather permitting, for the rest of the year. Reservation only, limited to 6 participants per day. Reply to HellyerAero at gmail.com

    Advantages of Hellyer Aero Testing

    Wind tunnels are expensive!
    ? You can expect to pay anywhere between $600-$1000 dollars for a 3 hour session which leaves you with more questions then you started with.

    Wind tunnels don’t have real world conditions.
    ? In most tunnels you are not pedaling with any power, you are just freely spinning your legs. Many people sit completely differently when they are applying power compared to free wheeling. Some tunnel positions can be super fast but totally unrealistic when you actually try applying power. There is no point saving 15watts of drag if you loose 30 watts of power.
    ? In tunnels your bike is fixed like on a trainer. Some positions make you unstable, which is slow. Field testing allows your body to move like it would in a real event, thereby showing if a position is really faster

    Testing wheels in wind tunnels is a huge waste of time
    ? Any time you want to change wheels the bike has to be removed from the sled and then reinstalled, which takes upwards of 15 minutes. That’s $50 up in smoke. At Hellyer its just a matter of changing wheels and you can be back on track. I’ll do the data analysis later.
    ? Most wheels are tested on their own which is silly since air flow over the whole bike matters. A “fast” wheel may not be that fast on certain bikes and others may perform better than expected.

    How it Works

    -Your bike needs to be equipped with a power meter and a speed sensor. GPS based speed is sadly not accurate enough. However, I do have two AnT+ speed sensors and two 175mm long SRAM SRM cranks that I can lend to people for the testing.

    -You ride whatever bike you want for 8 laps of the track however you want, you don’t need to maintain a steady speed or power. In fact variations in speed help the testing process. I recommend starting slow and accelerating throughout the 8 laps. Most people will probably be testing TT bikes, but this procedure will work on your road or track bike too, as long as it has a power meter.

    – If we are testing your position, I then need to download your computer and do some math and I get your coefficient of drag. This gives us a clear indication if the changes we are making to your position actually make you faster.

    -If you are just testing equipment then we can blast through way more runs and I can do all of your data analysis later and send you a report saying what was fastest etc after the fact. The data analysis takes a fair bit of time so we can do way more testing in the limited track time available if I can do the analysis later.

    -I tell at least 1% differences in CdA with my modeling, which is enough to say tell the difference between different skinsuits, helmets, water bottle placement, etc.

    -What about the wind? The modeling is very resilient against wind, because we are doing many small laps the headwind and tailwind will just average out and appear as small “hills” in the data. The drag number will just be the mean drag over the various yaw angles you experience over a lap.

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