Tilt Settings

[stevevarnum]

Is it normal to have to do a tilt calibration before EVERY ride? I set it in my garage. After the tilt calibration, I have a +1% in one direction and a -1% in the other. After riding, before I start my ride the next day, I check and it is ALWAYS off and usually about the same amount: +2% in one direction and about -.4% in the other direction. (Notice the "." in front of the 4%.)

If I don't do a reset my watts are approximately half of what they are when the tilt cal is done beforehand. It seems to me that I read the tilt cal only had to be done once? Is my unit defective or is this normal?

Thanks,
Steve Varnum

[coachboyd]

Which Generation iBike do you have?

If it's Gen 1 or 2, then the tilt can slightly change during the ride (due to bumps and normal road vibration), and this could be causing the discrepancy at the start.

[stevevarnum]

Sorry...I meant to indicate I have an iBike Pro Gen III (fully updated).

[bex]

I believe I have a very similar "issue" with my gen3 Iaero.
Tilt is off.
My mount is rock solid. Good batteries in mount, unit and sensors.
Bike is left out with unit on to get up to ambient temp.
Not sure what is left to do.
I have had a few issues getting the coast downs and calibration ride done with this unit, several attempts actually.
Not sure if they are connected.

Bex

[mtnsteve]

I have had repeated problems with my tilt calibratio on my gen 3 iAero, but it is not consistent. Some days I get good data and some days I don't. The problem has occured on 2 different bikes. Once during a ride I suddenly had a -20% slope on a mild downslope and then when I started going uphill it still showed downhill. On 3 different occasions on 2 different bikes,I could not get a good coast downs until I redid the tilt calibration which I had just done prior to the ride with the screen saying good tilt.

I have tried fresh batteries. Have checked the mount. Have checked my stem and handlebars. I have done a hard reset.

If I do a tilt calibration and then let the bike sit overnite without riding it, the next morning I get different readings in the same location (I take the bike inside on stone floors and place it against the wall to avoid forward and backward movements and have markings to assure the exact same location). And on slopes it won't duplicate the + and - readings after sitting overnite.

Have discussed this with John, but he is convinced the problem is me.

Any help will be appreciated as I really don't want to switch to power tap.

Steve Larson (Breckenridge)

[lorduintah]

I had two jumps in tilt today. Appear as major jumps in elevation (about 200 feet each) - so could it be the air pressure sensor is whacky and not anything else? Relatively calm day (5 mph)

Looking at the Analyze Power window:

I am attaching the csv of the ride. They both leveled out and the corrected slope is small.

Tom

[bex]

As a follow up to my previous post, I had some time discussing this with Aaron at Velocomp (by email).
He suggested I do the tilt sitting on the bike.
This enabled me to get beyond a "Bad coast" when doing my initial set up.
It was done on a tt bike. Stem mount, bars far apart (not what I wanted but it got me a profile)
I had tried the topeak bar extender but could not get any coast downs done regardless of how I did my tilt.
I am waiting for the wind port add on to arrive and then maybe I will get some success.
It appears my problem might be the bike rather than the unit. I created another profile on another bike with no problems.

What difference, if any, does the tilt make when its set up sitting on the bike? Why does that work?

Bex

[lorduintah]

It may be that part of the issue is that during the coast down segments, the iBike has no good tilt reference. The CAL ride determines the tilt by having the assumed out/back over the same terrain - thus the overall tilt average should be zero - and an adjust can be made with that assumption.

For the CDs - without a tilt at or near zero - you can get the calculations needed estimating that the ride is always up or always down and that component needlessly contributes to no convergence on the estimate for Friction and Crr. I know that when I get a bad coast down and the next thing I do is to check the tilt, it is off. (I just recently found that i had some movement in the mount and could change the tilt - so I had to make the mount more solid than I had previously. Now there is no movement at all and the CDs are even better than ever - reproducible...

Tom

[Velocomp]

Your huge rise in elevation at the beginning of the ride lasts 5 minutes. This would suggest that your tilt calibration factor and/or riding tilt stored in your profile is way off. What's happening is that the tilt correction algorithm in the iBike is catching the problem and fixing things after the 5 minute wait.

The same thing happens at the 18 mile mark, right after you've started from zero speed. Notice that the slope of the increase is the same. Did you stop there and perhaps do a Trip Reset? That would cause the same problem...

I would suggest doing a new tilt calibration and new Cal Ride to get the correct values of Tilt Cal and riding tilt in your profile.

[lorduintah]

John -

That's why I ordered two new bottom clamps for the handlebar mount. It was a little loose and once in a while pushing the controls would alter the tilt. Found out about that after I sent in that file. (I don't like using the 3M double sticky tape, but have chosen to use extra rubber strips to give the clamp enough grip on the handlebar.) I just have to be careful about the tightening of the screws.

Also using the iBike, I found that I had to lubricate my rear aero wheel - which lowered the Crr. The loose clamp also explains some of the erratic Friction values I have gotten - hitting the center button to set up the next CD.

Tom