Please Help: Calibration 'off'!

[smhagger707]

Updates on the 3 post down: I can't seem to get believable numbers. Too much effort with too little Wattage reported (under reporting) with the current profile (attached to 3 post).

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I took my first shot a doing a full calibration ride, followed by 15 coast downs (two I deleted as the Fric values were too low at 1.09 and 0.35-probably from getting passed by cars?). I just recently upgraded from an iSport to an iPro + Trainer and need to get my calibration set correctly so I can believe my data. Here's the details on my setup, build, etc.:

Male, 5' 4" (64"), 130 lbs alone, 154 rider+gear+bike; Tires: Continental GP4000s, 92 psi (front)/95 psi (rear), Rollout (with rider and all equipment) measured out to exactly 2096mm (700x23)-what a coincidence!; iPro mounted on bars (horizontally leveled), just to the right of my stem clamp (nothing in front of wind port). Handlebars are 40 cm c-t-c. Position = hoods (to slightly behind actually, near the bends). Road surface for cal ride was older chip-seal; surface for 7 mile ride afterwards was varied (the 4 minute interval and 1000+W sprint were on asphalt).

I originally had a lot of problems with my power dropping significantly on my iSport whenever I'd hit a bump in the road. Since upgrading, this thing seems to completely ignore bumps now-it's great! Read more detail (if you want) here: http://www.ibikeforum.com/viewtopic.php?f=26&t=1584 .

I don't know what files to send, so I've included a couple different files below. One is the profile saved, that is from the iBike software's 'Download coast down's and calibration ride' feature. I found some old coast downs that were still in memory, where the values were WAY off that were being averaged in, so I deleted all those (after I got home from my 7 mile ride, post-calibration, tonight-that file is attached also), along with two coast downs that had a very low (suspect they were when I got passed by a couple trucks) Fric value (0.35 & 1.09). (couldn't add the following: 'The next file is a pdf file with the coast down information, and which coast downs I deleted from the averaging.') Next, there is the ride file from tonight, post cal-ride and coast downs where I did a sprint and a 4 minute interval (Please note: the profile embedded in this ride seems to have the old/bad coast downs included in it). Finally, I've included a copy of my actual calibration ride. Like I said, I don't know what file(s) are needed to assess what my 'correct' profile should be (I think its close to correct now in the 'Master_100914_cal_data.ibcd4m' file attached below, but need someone to confirm).

Also, on the 'Download coast down's and calibration ride' feature, I didn't know which option to select, so I selected 'Crr adjusted' for creating my profile-I hope that was correct.

Please help.


Sean

[smhagger707]

Maybe it will be easier to get a 'thumbs up/thumbs down' if I list the params here as a reply, then the details supporting them can be evaluated in the files above?

Aero: 0.223
Wind Scaling: 0.687
CdA: 0.325

Fric: 2.937 (seems a little low to me, and I ride on chip sealed mostly-granted a lot of it is older so it's been smoothed out...)
Riding Tilt: -0.0%
Crr: 0.0043 (same comment as above-seems too low)

I think I'm going to tweak the fric / Crr values to use the following profile for a 'general' riding combination:

Aero: 0.223
Wind Scaling: 0.687
CdA: 0.325

Fric: 3.530
Riding Tilt: -0.0%
Crr: 0.0051

Am I on the right track, or does something need to be tweaked?

Thanks for the assistance with this...


Sean

[smhagger707]

Did a group ride tonight: 34 miles-something's 'off' with the calibration. There were times during the ride that I felt like I should have been holding 170W, while the unit read about 120W--just not right... Playing with the numbers, per the 'guide' listed here: http://www.ibikeforum.com/viewtopic.php ... Seal#p8859 I get totally bogus power levels when I bump up my wind scaling to what is recommended, and move the fric into the 'suggested' range-there's no way I can hold those power numbers.

This is getting really frustrating!

Coach? John? Someone?

Attached is a small ride file from the ride home (after the group ride) tonight...

[racerfern]

Can you upload that 34mile ride and label with an annotation where you expected the power to be 170 instead of 120.

To be honest, your numbers look pretty darn good.

[smhagger707]

Thanks for the reply. Actually, the file in post number 3 is an an example of what I'm saying regarding the 170 / 120 thing-right around the 4 min, 30 sec mark, and the 12 minute mark. I've annotated the file and attached it...

I've also included the main group ride file from last night. There were a few places where I did some pulls and expected the power to be higher than it was (annotated). I looked back at some similar routes and did notice that my NP of 169W / Avg Power of 124W does seem in the ballpark of what I've seen before, but my Average HR seems high for the effort (maybe lack of sleep, and a VERY stressful day?). It was pretty windy today (shows in the 2nd half of the data). I don't know, maybe the data looks 'ok' after the fact-what do you think?

I should mention also that I did slightly change my weight and wheel factor from what I was previously using: I was riding with a weight of 157-158 lbs total (now 154), and a wheel factor of 2115 (new tires, unloaded, higher pressure-now 2096). Also, I was using a Crr of 0.0081, so, I played with changing it back from 0.0051 up to 0.0062 (leaving weight at 154, WF at 2096) and it seems to help bring the numbers back in line. Changing those back does 'feel' a little closer to what I'd expect-though my 5 minute power seems a little low. Is that Crr too high for an average value (mostly older, smoothed out, chip sealed roads, some asphalt)?

Here's my 'pre-upgrade' profile: (for Ref)

Aero: 0.218
Wind Scaling: 0.698
CdA: 0.312

Fric: 5.660
Riding Tilt: 0.0%
Crr: 0.0081
Cal Weight = 158 lbs
Wheel Factor = 2115

Shouldn't my riding tilt be negative, and shouldn't the wind scaling be larger than 0.69?

I don't know: maybe my legs were just 'dead' at the end of the ride from doing too many sprint efforts and a 2 x 20 workout recently?

Again, thanks for the help...

[rruff]

Shouldn't my riding tilt be negative, and shouldn't the wind scaling be larger than 0.69?

The iBike auto adjusts for tilt, so even if your tilt is off, it will only be off for 5 minutes.

Check your wind scaling by riding back and forth at a good clip on a calmish day. It should add up to ~zero on the "analyze wind" screen. Look at this before doing "analyze route".

[smhagger707]

Thanks. Where am I looking on the 'analyze wind' screen for the wind to sum to approx zero? Also, is there any information to help me better understand what the 'analyze wind', 'analyze route', etc. functions do and how to interpret them? That would be most helpful.


Sean

[lorduintah]

Download the manuals or use the Help menu item to look at the documentation.

For wind scaling - on a relatively calm (ideally < 5mph) day if you ride out and back for a reasonable ride, your average speed and wind speed should be the same. The Analyze wind screen will show you the relative offset for a ZERO difference. A small difference is acceptable as haveing a complete cancellation is not always possible. What you do not want is a big delta of speed and wind.

Tom

[rruff]

Thanks. Where am I looking on the 'analyze wind' screen for the wind to sum to approx zero? Also, is there any information to help me better understand what the 'analyze wind', 'analyze route', etc. functions do and how to interpret them? That would be most helpful.

On the unit, you can bring up the average relative windspeed for your ride... this will give you an idea. The "analyze wind" screen is accessed in the software on your computer. Also remember to zero your wind offset before riding and check it often, because if that drifts it will screw up your wind values also.

[smhagger707]

On the unit, you can bring up the average relative windspeed for your ride... this will give you an idea. The "analyze wind" screen is accessed in the software on your computer. Also remember to zero your wind offset before riding and check it often, because if that drifts it will screw up your wind values also.[/quote]

Yeah, good point. I suppose I should look at the 'current' wind offset when riding and about to do an interval because even a slight negative wind offset could result in a significant loss in Watts--very significant when trying to hold near threshold. I should have thought about that and checked it while out riding...

[lorduintah]

Just remember that wind offset is done standing still and covering the wind port. Do not apply any pressure to the port - like trying to seal it off - just a careful covering of it with your hand.

Tom