Best tilt... level, slightly up, slightly down?

[rruff]

Just wondering if there is a consensus... is their an ideal tilt for the unit, or is it pretty much immune to reasonable deviations from level? Has anyone had a problem that was solved by changing the tilt?

[lorduintah]

I think a few degrees one way or the other are tolerable. What I might want to consider is the exposure of the wind port at various angles of attack. This may well have an impact on wind scaling - have not tried rotating the mount around - I put a level (iPhone, actually) on the face of the iBike display and got that to within a degree of flat. I figured that was acceptable. I thought I saw somewhere in the posts that up to 20 degrees would work.

Tom

[racerfern]

Just wondering if there is a consensus... is their an ideal tilt for the unit, or is it pretty much immune to reasonable deviations from level? Has anyone had a problem that was solved by changing the tilt?

Other than staying in the recommended -15 to +15 degree range I'm not aware of any issues or preferred mountings. I've never seen results change because you changed the tilt slightly. Your wind scaling will change for sure, but zero tilt is zero tilt.

[rruff]

What I'm curious about is if erratic wind measurements might be effected by the tilt.

[Velocomp]

The wind sensor operates independently from the accelerometer. The Tilt calibration and Riding Tilt will affect the frictional drag; Cal Wind and Wind Scaling Factor will affect aero drag.

Note that when doing a Coast Down tilt and wind factors DO interplay to the extent that the iBike is trying to get to a combination of aero and fric that will cause total watts to be zero. So, during coast downs if your tilt cal is wrong, say causing the iBike to think your bike is going downhill when it really is not, your aero number might be low (because your fric number is artificially too high).

Similarly, if your Cal Wind is wrong you'll get poor Crr values from a Coast Down.

This is why FW 400+ requires users to perform Cal Wind and Tilt checks just prior to Cal Rides and Coast Downs.

[rruff]

I'm wondering just about the wind sensor. I assume that a differential is taken between the pressure at the static port and the forward port. Seems like the airflow around the static port especially will be effected by the tilt of the unit. What I'm curious about is if the static port operates better in challenging situations (like gusting crosswinds) when it is at a particular tilt.

[Velocomp]

No, the two pressure sensors do not interact in any way.

[rruff]

No, the two pressure sensors do not interact in any way.

I guess I didn't understand how it worked... I thought it referenced the difference between static and dynamic, but I guess it only uses the wind cal as it's reference.

[Russ]

Velocomp said:

"So, during coast downs if your tilt cal is wrong, say causing the iBike to think your bike is going downhill when it really is not, your aero number might be low (because your fric number is artificially too high)."

So I am wondering if the iBike thinks I am going more downhill than I am, can this actually result in both aero and fric being lower than is correct?

Thanks,
Russ

[rruff]

If you have Gen3 the tilt adjusts automatically. On the earlier ones it is very easy to tell if the tilt is right in the software.