Hey all,
Not sure when the data's from, but I figured I'd add a couple of points that might or might not be useful.
1. Upturned verus flat hand holds on aerobar basebars: We designed, built, and tested both for Saxo when making the Shiv. We tested at 0 and -15 degrees. The flat hand hold bar on the fully built bike (-tare) was 502 gF at 0 degrees and 389 gF at -15 degrees. The angled hand holds were worse by 7 gF at 0 degrees (509 gF) and better at -15 degrees by 21 gF (368 gF).
We since have finished an extensive study at A2 testing the same exact control bike over 6 months of testing -- full yaw sweeps of the exact same bike tested ~1 month apart at the same tunnel, same protocol. At 0 degrees, the data over 6 months is within 9 gF. At -15 degrees, the data is within 35 gF (more vortex shedding, component of side force load cell, etc -- we should expect data at yaw to be worse than 0 deg).
So -- TAKEAWAY -- same shape, design of basebar with only the upturn changing, the drag difference is almost immeasurable. So, we've gone with the upturned hand holds as you simply don't crash when going down hills/hitting bumps! Confidence in handling with aero performance is key.
2. Note that the tare values at A2 are about 180 to 150 to 180 gF across -25 to 0 to 25 degrees.
3. Kestrel's Cervelo data seems high to me but the trends seem to indicate the same wheels were used between the Kestrel and the Cervelo. I'd assume tares have not been subtracted. Looks like bar spec could be significantly different though. I'll wait to hear more because the data's confusing to me too.
Thought the bar stuff might be interesting though.
Cheers,
Mark
--
Mark Cote
MITAerobike
Specialized Bicycle Components
Not sure when the data's from, but I figured I'd add a couple of points that might or might not be useful.
1. Upturned verus flat hand holds on aerobar basebars: We designed, built, and tested both for Saxo when making the Shiv. We tested at 0 and -15 degrees. The flat hand hold bar on the fully built bike (-tare) was 502 gF at 0 degrees and 389 gF at -15 degrees. The angled hand holds were worse by 7 gF at 0 degrees (509 gF) and better at -15 degrees by 21 gF (368 gF).
We since have finished an extensive study at A2 testing the same exact control bike over 6 months of testing -- full yaw sweeps of the exact same bike tested ~1 month apart at the same tunnel, same protocol. At 0 degrees, the data over 6 months is within 9 gF. At -15 degrees, the data is within 35 gF (more vortex shedding, component of side force load cell, etc -- we should expect data at yaw to be worse than 0 deg).
So -- TAKEAWAY -- same shape, design of basebar with only the upturn changing, the drag difference is almost immeasurable. So, we've gone with the upturned hand holds as you simply don't crash when going down hills/hitting bumps! Confidence in handling with aero performance is key.
2. Note that the tare values at A2 are about 180 to 150 to 180 gF across -25 to 0 to 25 degrees.
3. Kestrel's Cervelo data seems high to me but the trends seem to indicate the same wheels were used between the Kestrel and the Cervelo. I'd assume tares have not been subtracted. Looks like bar spec could be significantly different though. I'll wait to hear more because the data's confusing to me too.
Thought the bar stuff might be interesting though.
Cheers,
Mark
--
Mark Cote
MITAerobike
Specialized Bicycle Components