More average wind speed issues.

[dsingh]

Hi,

I got a Ibike gen3 a couple of months ago and am still struggling to make this work.

To recap, the issue was that no matter what I did to reset the wind offset, I have a consistent average wind speed of -2.5 to -3.5 on an out and back ride ( as seen in tools –analyze wind ). Much as I would like to think that I am blessed, I find it hard to believe that the wind gods would change direction every time just so that my biking is easier.

I tried doing some more coast downs and a calibration ride as Aaron had suggested to resolve the average wind speed issue.
However, the new calibration seems to be pushing things off way of course.

First, it took about 21 attempts to get 3-4 coast downs.

Second, it took 6 attempts to get the calibration ride. This, thanks to the new ‘feature’ on firmware 3_09 that automatically starts a back ride when the out is finished. So every time I pushed the center button as per the documentation, It would abort the ride. This gets really frustrating. How about actually documenting this change. Even the videos show that you have to press the center button.

Third, the cda/crr numbers are way lower than they were before – for the same bike/setup. ( it used to be .458/.0045 now its .304/.00282 ) I don’t think the bike has gotten slipperier over the last month but maybe if the data is correct and this continues I can stop pedaling altogether.

Overall, I can only describe my experience with the Ibike as being exceptionally frustrating. Its definitely not very confidence inspiring to do the same thing over and over again and see different results. I consider myself a rational person - with over 20 years experience in embedded electronics and this has to be most irascible designed consumer electronics I've come in the last 15 years or so. At this point I find it hard to imagine this can ever be a serious training tool. I spend more time playing with this stupid gadget in one day than I spend training in a week. Going by some of the post here, it seems that may not be so different for a lot of people who spend more time posting and tweaking than actually using the unit.

Sure enough, the new profile doesn’t help the original problem with the average wind speed. And yes I did follow explicit instructions on zeroing the wind offset, letting the temp compensate etc.

Anyone have similar experiences or insights would be really helpful.

[coachboyd]

This is why we are heavily active in getting firmware 4.00 out to you guys. We really want it to be easier to set up and get a consistent and more reliable calibration process.

If you send me a solo ride file that started and ended in the same place that was done on a fairly calm day I can check over your wind scaling values. Just send a file to boyd (at) totalcyclist dot com.

[rruff]

I have a consistent average wind speed of -2.5 to -3.5 on an out and back ride ( as seen in tools –analyze wind ).

That is definately a Wind Scaling issue, which can be solved by changing it, since it seems to be consistent. Wind Scaling is easy check at any time now with the Abs Wind feature.

First, it took about 21 attempts to get 3-4 coast downs.

Why?

Third, the cda/crr numbers are way lower than they were before – for the same bike/setup. ( it used to be .458/.0045 now its .304/.00282 )

I also noticed a bit of randomness with my Gen3 Pro in the beginning, but it settled down after awhile, and the Wind Scaling also dropped a lot. It seems pretty stable now.

Have you gotten the issues resolved yet?

[dsingh]

That is definately a Wind Scaling issue, which can be solved by changing it, since it seems to be consistent. Wind Scaling is easy check at any time now with the Abs Wind feature.

I am assuming you go and manually change the calibration file to fix this - Is there a science to this or do you just putter around until it looks good. Do you save it as a new profile then ? Also how does the Abs wind feature bring this out. I am assuming if the abs wind shows a reading then it means a wind scaling issue - do I need a really calm day to check this out ?

First, it took about 21 attempts to get 3-4 coast downs.

Why?

It kept saying 'bad coast' while I was doing the coast downs. When I came back and downloaded the coastdowns, it shows all the coasts including the aborted ones. I noticed there that the friction numbers on the aborted rides were all negative. I had huge variations from -11.37 to 5.18 for the friction and .15. to .68 for the aero. Again this sort of wide fluctuation across what are identical conditions ( i even use the same piece of smooth road - one measurement going one side and then another down ) doesn't inspire a lot of confidence.

I also noticed a bit of randomness with my Gen3 Pro in the beginning, but it settled down after awhile, and the Wind Scaling also dropped a lot. It seems pretty stable now.

Its interesting that your Gen 3 unit changed characteristics - did you make any changes to the setup that helped or is it just the something that happened by itself ? How long did it take before the unit stabilized.

Have you gotten the issues resolved yet?

Nope - not yet. I sent my ride file and some pics of the setup to Boyd. Boyd mentioned he would use that to estimate my Cda. I do find it a bit disturbing though that there seems to be an acceptance that tweaking the Cda/Crr numbers is right approach. I would have thought the point of instrumentation is to move away from having to guestimate . The RPE scale is supposed to measure subjective load while the power meter is supposed to measure absolute load

[lorduintah]

I have found that bad coast is likely due to a bad tilt calibration. You may have done a tilt calibration, but if your mount is not secure - pushing the buttons can change the tilt of the meter enough to lead to this.) The second most likely is hitting the brakes during the coasting.

Tom

[R Mc]

Part of the problem, (assuming I understood your post correctly): every coast-down should occur in the same direction, not alternating directions.

[racerfern]

Tweaking profiles is not the preferred way and moving away from instrumentation at least circumvents the designed system. However, you had sooo many weird numbers it could take a lot of forum messages to nail down what the offending issue really is. It could be the iBike, the bike; it could be operator error, a misunderstanding or it could a setup problem. In a case like this it's easier to let one of the more knowledgeable persons cut to the bottom line. Then, if there's still an issue it's easier to nail down the problem.

Most users do a few coastdowns, a calibration ride and are done with it. Once in a while it doesn't work quite that easily but we'll all do our best to get you dialed in with as little aggravation as possible.

[coachboyd]

I have found that bad coast is likely due to a bad tilt calibration. You may have done a tilt calibration, but if your mount is not secure - pushing the buttons can change the tilt of the meter enough to lead to this.) The second most likely is hitting the brakes during the coasting.

Tom

That was the problem in this case.

The iBike has to be very secure, the accelerometer is VERY sensitive. It can measure to the tenth of a degree and updates 16 times a second. If it's not secure and you press it before doing a coastdown, chances are you are going to get a bad coast.

[rruff]

I am assuming you go and manually change the calibration file to fix this - Is there a science to this or do you just putter around until it looks good. Do you save it as a new profile then ? Also how does the Abs wind feature bring this out. I am assuming if the abs wind shows a reading then it means a wind scaling issue - do I need a really calm day to check this out ?

Do an out-back ride (best would be several "laps" over a short course) anywhere and any time you feel like it. If you reset before doing this, then you can look at the average Abs Wind on the iBike when you are done... zero is the goal. When you get home, go to Analyze Wind in iBike3 and highlight the this portion and look at the ground wind. If it doesn't read zero (or close to it), then the proper correction is WS(new)= WS(old)*(Vb/Vw)^2. Obviously WS is something that should be stable from one day to the next.

Also if it is calm you should see ~0 all the time on the Abs Wind display.

It's better to do it when it's calm... but you can still do it on a windy day... if you have a road with no traffic that is very open, or where you can ride on the same part of the road in both directions. Make sure you minimize any time when you might have a net tailwind, and do several laps to reduce the effect of wind variations.

I had huge variations from -11.37 to 5.18 for the friction and .15. to .68 for the aero. Again this sort of wide fluctuation across what are identical conditions.

I think you are making a pretty good case that something is wrong with your unit... or something very wrong with your setup. There is no problem with going in two directions when you do CDs.

Its interesting that your Gen 3 unit changed characteristics - did you make any changes to the setup that helped or is it just the something that happened by itself ? How long did it take before the unit stabilized.

Scratch that... I just went for a ride with my new external battery mount, mounted in the same place as before, and the Wind Scaling jumped from 0.9 to 2.8! I did 3 separate tests during the ride, and 2.8 is the new number. I have no idea why.

I do find it a bit disturbing though that there seems to be an acceptance that tweaking the Cda/Crr numbers is right approach. I would have thought the point of instrumentation is to move away from having to guestimate . The RPE scale is supposed to measure subjective load while the power meter is supposed to measure absolute load

The calibration procedure should give you the right values. If you'd like to be precise, you can do the calibration 3, 4 or more times in different conditions and average the results... or you can tweak your numbers if you wish and have some reason to believe you know better.

But first the unit itself needs to be giving consistent info. It doesn't appear that yours is. My Gen3 is displaying some odd behaviour as well. The Gen2 I bought last summer has always been consistent though, so it isn't an inherent problem with the concept.

[dsingh]

Thanks for the replies everyone. Sorry, I've been late in replying. I broke my clavicle in a motorcycling accident last weekend so looks like I'll have to wait a few weeks before being able to test out the unit again. Boyd is looking into getting me a stem mount as well since he is fairly certain the mounting is the issue.

I'll keep you posted - right now I have to get to surgery tomorrow for a plate. And yeah - it sucks to type with one hand.