Positive Riding Tilt?

[smhagger707]

I went in for a professional fit tonight and had really good weather conditions to do another calibration ride. On the forums, I’ve heard coach Boyd say the best thing to do is to run through the ‘fast start’ option and do a cal ride, skipping any coast downs, to get the best profile possible-so that’s what I did tonight. However, when I downloaded my data, it shows I had a positive riding tilt (+0.1)-I’ve read that I should never have a positive number here so what should I do? Do I just simply set ‘ride tilt’ to zero and let the Fric or Crr be automatically adjusted under ‘edit profiles’ in the ibike software? If so, which parameter should I have the ibike software automatically adjust?

I’ve attached the calibration ride file for reference.

Here are the factors that the unit came up with (the fitter put a longer stem and narrower bars on the bike, I feel like I’m now more aero so I believe the lower aero and CdA numbers, also the unit is now tilted slightly upwards where it was dead flat before):

Aero: 0.193
Wind Scaling: 0.620
CdA: 0.311

Fric: 3.506
Riding Tilt: 0.1%
Crr: 0.0060
Cal Weight = 156 lbs
Wheel Factor = 2096

[pjboyle]

I'll leave the file analysis to the experts, but have to ask, did you do a good tilt procedure and wind offset immediately prior to embarking on the cal ride? The old tilt stored in your profile will be incorrect due to the stem change.

PJBoyle

[smhagger707]

Good question: yes, I did a wind and tilt calibration immediately prior to the cal ride (after the fit was over).

[racerfern]

Are you on a TT bike? Depending on how much you're pulling on the bar ends you end up with very little tilt and could end up with the slightest positive tilt. It's unusual but it could happen.

However, if you're on a typical road bike setup you definitely won't have positive tilt.

[smhagger707]

Are you on a TT bike? Depending on how much you're pulling on the bar ends you end up with very little tilt and could end up with the slightest positive tilt. It's unusual but it could happen.

However, if you're on a typical road bike setup you definitely won't have positive tilt.

That's so interesting that you say that as it honestly does describe my experience during the cal ride: I feel like I am in a TT position now with my arms extended forward, my elbows tucked perfectly in as though they're resting on elbow cups, and my wrist bend identically to how they would be if I was holding aero bars. And 'yes', I was tugging the hoods exactly as you described-I was quickly running out of daylight and was holding a decent pace in order to get back to the car. My new bars are 38 cm C-T-C and my shoulders measure 37 cm so I'm probably as aero as a normal sized person in a TT position, to be honest. Actually, the way I described my new position to my wife after the fitting was that I felt like I was in a TT position. She was fitted by the same guy two weeks earlier (she loves her new position, btw) and said she totally knew what I was saying-she felt similar.

After reading your comments and seeing the numbers from a very short 1 mile ride after the cal, I really feel like the numbers are finally 'good'-and that was with the 0.1 riding tilt. Honestly, this profile finally ‘feels’ right and produces numbers that I would expect under effort (in the past I’ve always felt like the numbers just felt ‘too low’). I've attached a small 1 mile file from after the cal ride if that helps any...


Sean