Gen III and Riding Tilt

[iodaniell]

I think your questions are addressed in the new manuals for the GEN III devices.

[mlennox]

Are these manuals located online somewhere?

They were posted on the forums I believe, but I'm still a little confused about this issue also. The manual seems to imply that even if your initial tilt calibration (which now requires an extra step of turning the bike 180 degrees) is off, after a few minutes of riding the auto-adjust feature will correct the tilt. However the manual seems to imply that you still very much need to perform the pre-ride calibration.

I guess my question is this.

If you don't care about the first few minutes of your ride (or even the first 15-20 minutes), can you simply get on the bike and go with Gen III? If you assume that day-to-day variances in rider weight will have minimal impact on power (good assumption), and if the tilt and wind calibration will auto-correct on-the-fly, are you now able (with Gen III) to simply hop on and ride and expect to get good numbers once it has had time to make the necessary adjustments?

[Velocomp]

You need to do an initial tilt calibration and Cal Ride when you first set up your Gen III iBike. Once these initial calibrations are done your iBike will, in fact, self-correct tilt on each subsequent ride.

For those of you who do only 5 minute long training rides you should check tilt before each outing; otherwise, there is no reason to check tilt every time unless you've changed your setup substantially or something has been bumped severely.

[coachboyd]

Riding tilt is not irrelevant still. I was thinking the first thing at first, but it was explained to me that riding tilt is still needed to separate total friction and crr numbers. For example, you can have a lot of friction and a lot of riding tilt and have a low crr. Riding tilt is the only way to differentiate between the two.

There is now a "cal ride" with the Gen 3 models. This is a 2 mile out and back ride that will store your wind offset and riding tilt in the unit. Once you do that cal ride, I have done a lot of my rides where I just put the iBike on my bike and go out for a ride. . .and I have been getting great results.

[rruff]

You are saying that the riding tilt (the difference between laden and unladen tilt) is still an important value to know and that makes sense. But... seems like the unit should compensate for any changes in the riding tilt at whatever its update rate is. I'm curious to know how often this is exactly... seems like it is at least a few minutes, so it won't pick up frequent changes, but it is still a big improvement.

Also, I don't see a reason why it couldn't display actual slope rather than the unladen slope. This is just a curiousity, but it can be confusing to people who like to pay attention to such things when they are riding.

[coachboyd]

The new unit does. If you are riding along and you have a riding tilt of -.4% the slope shown on the road will compensate for that. Meaning, say that you are going down a -1% descent. If you were to go into the setup screen, on the tilt calibration screen you would see -1.4% (the actual angle the ibike is pointing). But in the enviro screen for slope of the road, it would show the actual -1%

[rruff]

Is the Gen III tilt sampling rate frequent enough to adjust for whatever is causing these variations? Or does Gen III not compensate at all for this type of error? My mount is glued to my stem, and the changes appear to be more related to weight distributuon on the bike.

One thing I've noticed when playing around with the numbers is that sometimes the altimeter gives wonky data for awhile. I guess this makes some sense since it can be effected by wind... or maybe it is something else. Anyway, I think its ok to have a fairly sizeable sample of altitude data before tweaking the slope... but it would be nice to know what this is and maybe even adjust the frequency of updates.

Regarding the variation in slope in real time... I was noticing this after I put a new stem on my bike, and it was because the headset was just a little bit loose.

[racerfern]

Tom,

I'm flattered to be on the short list (I think:) ). I know you had issues with the Gen2 and I'm not sure why. They really do work very well. But I don't want to have that entire discussion again. I want to show you some real results of a Gen3 ride.

I just completed a 55 mile ride with 5250 ft of climbing using an early version of the Gen3. Take a look at the results. I know someone is going to mention the vibration zones. Forget about that. The unit I was riding with had one of the original accelerometers from a Gen 1. This was a group ride in which I would get dropped at every climb and would have a great group of guys waiting for me at the top. Luckily I wasn't the slowest, but darn close. Of course I was the fastest down the hills. It's amazing what a few extra pounds can do in that respect. Being fearless helps a bit too.

Look at the slope over the 55 mile distance. There is less than a two watt difference! With huge barometric changes as we went from 200' above sea level at the start to over 1000' and back five times. Add to that significant temperature changes from 59 at the start to 92 at the top of the fourth climb. Notice that the elevation start and end are nearly at the same point through all these weather variations.

Bottom line: If the Gen3 doesn't put a smile on your face, nothing will.

[iodaniell]

Look at the slope over the 55 mile distance. There is less than a two watt difference! With huge barometric changes as we went from 200' above sea level at the start to over 1000' and back five times. Add to that significant temperature changes from 59 at the start to 92 at the top of the fourth climb. Notice that the elevation start and end are nearly at the same point through all these weather variations.

Bottom line: If the Gen3 doesn't put a smile on your face, nothing will.

It looks like that the second case of vibration got the accelerometer into an ascending mode. Perhaps if you had the newest accelerometers the tilt line difference would have been even less.

Regardless, 200ft of change over about 290,000ft travelled and over a temperture change of 30 degrees F is very good.

It will be interesting to see how the Gen III does in colder climates. We in the mid-Atlantic are already seeing morning temps in the mid-30s F.

[racerfern]

From one extreme to another. The picture below is from a ride I did yesterday afternoon. This flat ride is up the coast about 11 miles, then back. This is about as flat as it gets with only a few gentle rises and falls. The entire ride has one overpass. This is also one of the most challenging rides to track elevation changes on because at sundown there can be significant changes in pressure and temperature. This happens as the winds change from offshore to onshore. My Edge 705 is severely challenged with this ride even though it has the advantage of GPS elevation assistance. Before anyone comments about the green line, remember the scale. This is virtually flat and the Gen 3 adapts to it very nicely.

Below you have the slope chart along with an elevation chart from my 705 and the same chart in the same format from the Gen3. The Gen3 did a better job at elevation than the 705. These screen shots are from importing the data into SportTracks. I "moved" the scale so both charts would show the same elevation total along the "Y" scale. I hope I got it right.

[coachboyd]

If something happens in your ride to change your riding tilt, the new iBike will make those corrections. It would be the same thing (on a much smaller scale) as if you were to loosen up your handlebars and turn them upwards. You will get a time period of numbers that aren't right, that will be corrected when the algorithm runs it's course.

Of course, if your riding tilt changes by going into a climb and you have less weight on the handlebars, chances are it's going to change by .2% of a degree or somewhere around there. So, the first few moments of the climb where your wattage could be off, it won't be off by very much (in fact, it's been hard for me to even notice when I run power meters side by side).

For this new unit, the purpose of riding tilt is more for getting an accurate crr number. Any changes in riding tilt (as small as they are) will be corrected on the fly.

[racerfern]

Tom,

Sometimes I wonder if you are trying to understand the iBike, fight it, or design your own competing product. No offense intended of course. I can appreciate your interest in making sure this generation lives up to its expectations but I do think you are trying to over-analyze some of this.

A lot of product developers and testers already did tons of over-analyzing. These people put in hundreds (probably thousnads) of hours both in front of a computer and riding in all kinds of test situations and of course typical riding situations to make sure this Gen3 was everything Velocomp planned and intended it to be. I don't think it matters if the error introduced in slope is because of changing environmental conditions, changing position on the bike, loose or worn parts. As long as the starting calibration is good, you will get excellent slope results.

Every single out and back ride I've done, from 10 miles to 100 miles with the Gen3 has returned an average slope of between -.1 and +.1 on the Gen3 and close to zero on the software. To me, that is fabulous.

My ride tilt on the flat ride is the result of the slope "self-correcting". You are correct in that maintaining an accurate slope reading on the flats is probably more challenging than on a steady climb. The green line is far from flat because the exent of movement in the "Y" scale is less than 25 ft so if you think about it, it is VERY flat. I tried changing the scaling on the "Y" to give it a more realistic look but it wouldn't change. You can change scaling on the main graphs but not on these secondary graphs.

[rruff]

I wish it were so simple as a headset adjustment, but I have had the same problem now with three different bikes, including my new S-Works Tarmac Sl2, which has one of the stiffest fork/headset combinations in the business. Glueing my mount did seem to help, but not eliminate the problem.

Sorry to hear that... maybe I'm just a lucky one. I'm almost always +-.05% on tilt. long climbs and descents don't have much effect. In fact the software correction often introduces more error than it removes. I'm hoping that there is a way to turn the auto-correction off on Gen3

[Russ]

Raceferns ride data is great! Just to restate his comments about the exagerated green line variation. The X scale of only 35 feet shows a maximum, by eye, difference of about 20' between the blue and red lines. This 20' max difference is in the noise on a ride with high changes in elevation where the X scale goes to hundreds of feet or more. If you could expand the scale of one of those rides, the green line would look just a ragged as Raceferns flat ride! Think of it as an mental illusion

As to the GPS plot, looks like Racefern did not bother to set the initial elevation in the 705 (I assume he could as I can with my eTrix). Keep in mind with GPS, that 'selective availability' is actually still on but to a lesser extent since it was eliminated. It was not eliminated for the vertical axis and is used even more when DOD deems it necessary, probably in Persian Gulf region for example, as a guess. My experience (at average 200' above sea level and a daily trip to sea level during the work week, is that it frequently seems my Honda Civic is actually a submarine! This is with the gps correction of the altimeter selected.

I have been too busy all week and am just catching up on posts.

Anyway, genIII looks great, breathlessly awaiting the arrival of mine!

Russ

[racerfern]

Unfortunately I can't set a starting elevation on the Edge 705. I've been clamoring for that with Garmin since the 305 was introduced. The graph you see is the raw data that I manually correct in SportTracks because it irks me to see inaccurate elevation profiles. The Gen3 definitely handles these situations better.