bugno

Cycling time trialist, fluid mechanics engineer, created an app for a cheap DIY aero system.

[bugno @CdaCrr]

3rd on saturday TT (22 km), 10 seconds behind the winner. Apparent CdA of 0.223. Big thanks 👍 to @LaurentJ56 for his @SwissSide wheel.

[bugno @CdaCrr]

@lopey66 A CdA of 0.190m2 is 19dm2 or 1 900 cm2 or 190 000 mm2.

[bugno @CdaCrr]

Hard work, 6*10mn #threshold #L4

[bugno @CdaCrr]

Typical histogram for a group ride. Large amount of time with drafting seen as #tailwind by the @weatherflow anemometer.

[bugno @CdaCrr]

@pbljung @PowerTap Yes same gears, constant speed. Just roller resistance changed during a 6*(90s@on+60s@off). I deleted the BA cause it didn't match the current histogram 😅

[bugno @CdaCrr]

Need to change the title "Chain" to "Transmission" loss as the power relative difference (30s average) between #P2Max and @PowerTap hub is a sum from several sources: chain, bottom bracket bearing, rear derailleur pulleys. Unless I'm mistaken.

[bugno @CdaCrr]

@NickDart2 @PowerTap You are right. I have many other plots there the relative difference moves from 0 to 10%. The difference may be constant (+/-0.5%) during a whole session on the trainer if I keep pedaling and not changing gearing. Outside, it is a completely different story.

[bugno @CdaCrr]

@tanhalt @PowerTap You are right. I am confused.

[bugno @CdaCrr]

@tanhalt @PowerTap May be wrong, but it would measure BB bearing drag.

[bugno @CdaCrr]

Monitoring #heartrate acceleration/deceleration at start/end of intervals. The first inflection point is around ~30s whatever #cycling #intensity. The second one during #recovery depends on the session: ~30s for L3 work, moving to 60s and even 80s for L5 and more... Any thoughts?

[bugno @CdaCrr]

Today, less wind and more drafting from cars. We clearly notice it: non-symmetric distribution and a negative skew.

[bugno @CdaCrr]

Difficult to say for sure that anemometer was well calibrated when analyzing wind data (Cf×airSpeed-bikeSpeed) collected during today 3 hours ride. Bin width should be reduced from 1 to 0.3 km/h probably...

[bugno @CdaCrr]

In previous graph, data was in m/s and plotted as km/h...😅 One week later, with a 15-20 km/h wind prediction from the station (according to the app, it was headwind during 52% of the time). For the moment, I suspect Cf is slightly too high...

[bugno @CdaCrr]

@pbljung @Notio_AI Any CdA mean value for each set ? May be wrong, but the calibration of Notio is not perfect with Cf too high, and CdA absolute values too low... But, it doesn't change the quality of your results.

[bugno @CdaCrr]

@pbljung @lanierbenkard I guess Ant+ cadence is not 0 and stay exactly the same?

[bugno @CdaCrr]

#Linear #regression may be misleading. Same data, two plots and different conclusions. Left plot: Strong correlation between 2 #powermeters (delta 2.2%). Right plot: No, #accuracy for one (PowerTap G3) is bad at high speed after #autozero. Data from 3*20mn@270W trainer session.

[bugno @CdaCrr]

@lanierbenkard @pbljung Good point 👌

[bugno @CdaCrr]

@pbljung @lanierbenkard Maybe Ant+ another default. Have seen that with Assomia pedals+Garmin computer (Ant+). With Assomia pedals + CdaCrr computer (BLE by default), no issue. But, instead of sending 0 power each second, few seconds before sending 0 again...

[bugno @CdaCrr]

Each climb has its signature, that given by the coating quality (left: cobbles from the #Tremola pass, right: col du #Cucheron). RMS of vertical acceleration recorded on a #Samsung Galaxy J5 phone:

[bugno @CdaCrr]

Use of a @cdacrr metric (power estimation at sea level, Peronnet 1991) when riding the famous cobbled #Tremola pass.

[bugno @CdaCrr]

@pbljung Slow out and back (~1mn) with CdA~0.36 hypothesis.