Adjusting riding tilt in a profile

[Russ]

I don't know if any of my experience is relavant but here it is.

My two normal positions on the bike are on the prodesign aero bars and the hoods.
The hoods give me a greater downward tilt than the bars.
I haven't isolated another possible contrib yet but I think that sliding forward and
to the rear on my saddle have some affect.

Prior to going to the stem mount, if I pulled up or pushed down on the bars, my
tilt changed, which I found myself doing without thought.

Russ

[travispape]

Well, less than a 10 W difference is decent, but it should be better most of the time. It is interesting that tilt was fine until you got to your first climb--similar to one of your previous rides. Ride with the tape a few more times to get a good bead on the trend.

Other than that, it sounds like the best things to try is to have your mechanic get your headset torqued up to spec on your Tarmac and to get some rides in with your winter bike.

Travis

[rruff]

Also, tilt is typically the same after a ride as before (I know Travis says this is not sensitive enough, but some days I do see a difference).

It will be accurate enough to tell the large deviations you are seeing. An error of .1% in tilt is easy to spot, since the difference when you flip the bike would be .2%. You can even do it on the road. I put little rocks on the pavement to align my wheels. I think this would be a good thing to check often and keep notes... if you continue to have problems.

[chrispy]

It is just the on-the-road power numbers that are at stake in this thread. If you are using the power reading to pace yourself or for doing intervals, then the effort to debug big problems with the tilt is worth it; however, if you are like me and primarily analyze your power numbers after the ride, then just do so after the iBike2 fixes the tilt.

I do use the on-the-road power to help with pacing (intervals and time trials). Today I did a 10-mile TT, and had a much larger tilt correction than I typically see in everyday riding. Could this be due to torsion from pulling on the bars (I do not have aero bars)? Would a stem mount be more resistant to such fluctuations?

I still need to sticky tape or epoxy my mount down and re-do my calibrations. That said, I was thinking of setting a pre-correction tilt of the average of my observed iBike 2 tilt corrections, plus or minus a standard deviation (depending upon whether I want, on average, to see a slight overestimation or underestimation of my on-the-road power).

All of this said, I don't blame the iBike for anything in today's TT (I actually did pretty well). I could probably dial it in a bit better if the on-the-road power was more accurate, but then, I could also dial it in better with more practice.

Thanks,
Chris

[travispape]

I do use the on-the-road power to help with pacing (intervals and time trials). Today I did a 10-mile TT, and had a much larger tilt correction than I typically see in everyday riding. Could this be due to torsion from pulling on the bars (I do not have aero bars)?

Maybe pulling on the bars could contribute some, but I don't think it would create a big overall trend in the tilt. It would be something to watch out for if you had aero bars with your elbows on pads, but if you just have your hands on the bars I don't think you would generate nearly as much torque. As you stand or move between the bars, hoods, and drops, you may see localized changes of tilt due to redistributing your weight.

Would a stem mount be more resistant to such fluctuations?

I have an iBike on the stem and 2 on the bars and I have not seen a big difference in stem tilt versus bars tilt. That said, it is gererally easier to do a good mount job with the stem mount. I've gone the epoxy route, so all 3 mounts are good.

Travis

[rruff]

I have an iBike on the stem and 2 on the bars and I have not seen a big difference in stem tilt versus bars tilt.

I kinda wonder where the tilt is coming from. Everyone has more weight on the rear tire, so that would tend to tilt up, not down. My guess is that fork and steerer account for most of it, and it makes sense that the difference in tilt between the middle of the stem, and the bars right next to the stem, would be very small.

[rruff]

Any feedback as to how these files compare to other user files would be appreciated, as well as any additional advice you might offer.
Thanks

Looks pretty good. Did your second ride start and end at the same point? If so, the elevation is off as much as the slope, and it is a very good result. In the first one it looks like you get more of a downward slope on the climbs and it is pretty level elsewhere. I get a slight upward tilt on uphills and downward on downhills... which makes sense to me. Don't know why yours is different.

One thing Travis brought up recently was a possible effect of solar heating and warpage. Might want to pay attention to whether this correlates to any deviations. If it is a cloudy day then this wouldn't be an issue. Anyway, these two rides look fine... especially the later.

[travispape]

Ron had some good observations.

Tom, we keep seeing this pattern in your rides--not all, but in several of them now--where the tilt is fine until you start actually climbing. It happened again on your 12 mi ride above right at the start of the climb. I wonder if you do anything to shift your body weight as you get ready to dig into a climb. Another posibility is that maybe you torque the bars some with your ride position. Something I have played with in the past is to grab deep in the drops where they are vertical. In doing so, I have noticed that I actually torque down on the bars to hold my torso in a low aero position. I'm just wondering if you might have a ride position you get into before climbing where you can feel yourself torquing down on the bars?

[racerfern]

Tom,

I wrapped my friend's carbon fiber stem with one layer of electrical tape to protect the stem. I also applied one layer of a very thin (.030") of double sided tape to the underside of the wireless mount head. This thin tape compressed almost completely. I may as well have put one layer of electrical tape to the bottom side of the head. If your stem is not very round then use the tape on the clamp side, maybe even two layers. Regardless, on the top side, only use some solid filler; epoxy, shoo goo, whatever.

I then had someone hold the mount level while I squeezed in epoxy. You can cut away any excess tape to make it look better. After tweaking the tilt calibration I am satisfied that this is an excellent setup.

Finally, I added one step to my preride ritual, I give the front wheel of the bike a good bounce and then do my tilt cal. It seems it settles everything. The last few rides have produced results similar to today's ride of which I am attaching a picture.

[racerfern]

Do you think having the iBike near level is producing better results for you?

Yes I do. I think the wind offset is much more accurate and I get less swing and movement being on the stem. While I was going to the stem I took the time to make it level, eliminating or reducing one possible trouble point.

On my ride to work, the green line tends to slope upward slightly and there is an increase of 300' of altitude. On the way home, the green line tends to slope slightly downward and there is obviously a 300' decrease of altitude. However, the difference in wattage before and after analysis is negligible.

Living right on the ocean presents a challenge for me also. There are significant barometric changes as I make my way inland so the elevation and slope lines can differ by quite a bit.

I think that because of all these discussions we will see improvements in the iBike and its firmware that will make the unit even better. Regardless, I love my iBike. For intervals, long hill climbs where I need to pace or any type of training activity it is on the money.