vanilla ice wrote:Right, so if he's saying 1/2mph at 20mph, then at 35mph its a 1.5+mph gain..
Or looked at another way- All of the benefit of a goofy aero helmet, minus the goofiness!
1/4 mph at 29 mph on a real race bike. About 30 seconds on time over a 25 mile course. But that is a full disk not one just covering the short 6 to 8 inch spokes on an e-bike with 26 inch wheels and a huge hub.
Also the weight of that rear wheel will keep you pretty steady in a cross wind. Little people get blown around a little with a disk but big guys or (heavy bikes) hardly notice they are there.
You'll definately save a few watts but for most it won't be enough to be worth the effort unless they like the looks.
Observed tests this May:
I practiced on my TT bike on our state championship course and did 10 and 15 miles test runs for weeks before the event. I used TT bike with regular helmets and regular wheels and average speed was 26 and change. Race day we had much cooler temps and I had skinsuit, aero helmet, $3,000 Zipp disk and deep 1080 front wheel, 160 psi in the tires, tapered my training for the last week and I averaged 27.7. So all that stuff got me less than 1.7 mph. Biggest contributer was training taper and cooler temps, they probably gave me 1 mph. So maybe 0.7 for helmet, suit and wheels? Front aero wheels yield about twice the advantage as rear says other experts. 0.7 mph is huge in a race because it means about 45 seconds over the 25 mile course. Difference between winning and second that day was 30 seconds, but in past I have lost a race by 1 second.
Hope this helps.