why do I keep getting loww crr and aero numbers?

[GWPOS]

I posted my new cal ride I did after going and getting fitted at the local bike shop. I have not heard back yet, but was wandering why my crr is so low all of the time. I did 2 4 mile cal rides with coast downs and they are both low. Also my tilt is different on each one of the cal rides. Tire pressures where the same and the unit is mounted rock solid, and does not move at all. I have been playing with my unit so I can get my once and for all GOOD profile but I am a little confused what to change and which one of the two profiles I should use. I am posting both of my cal rides again below in case someone can give me some guidance. My CDA came out higher than I was told to use and want to know what to set it as as well. thanks.

100513_0701_cal_ride_AB7E100E.ibcd4m

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100514_0706_cal_ride_AB7E100E.ibcd4m

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[racerfern]

I have to recommend that your out and back laps be at the same speed, something around your general average.

I agree, Crr is low and that could be skewing the data. Separating Crr from CdA can be a challenge

Other than that, your data is excellent. Forcing a Crr of a typical road bike at .055 gives you a CdA of .344 for one set and .326 for the other set. Why not set:
tilt at -.5
wind at .595
Crr at .05
CdA at .333

Then do some rides, you can always tweak it later. As long as you set some benchmarks you'll easily be able to track your progress.

[GWPOS]

Thanks racerfern. It has been a little while since I bugged you. I know I could just use anu number and start training and will improve. I was just trying to get good numbers like I had before I messed it all up when I changed my stem...twice. I already had an FTP established and have been making progress, but now I guess I will just do another FTP test this week to have a new number to work with.

I ended up using these numbers below and have done 2 rides and the power numbers seem pretty good. I even did an out and back and my wind scaling came out really good.

tilt= -.6
wind=.595
CRR=.0046
CDA=0.369

All I need to do is some kind of rides or something to verify that all is right I guess. Thanks again..

Clint

[racerfern]

Those will work just fine. What tires do you use?

You know we're only about 70 miles away from each other. As a matter of fact I do a climb at GMR which is fairly close to you. It's great for establishing FTP. About 40 minutes of constant climbing though not killer steep as the average grade is only 5.3%. This link is the ride where the first hairpin to the left then 6.5 miles up is the test. After that it's rollers the rest of the way. Let's get together and ride it some time. I'm due for a field test in the next few weeks. http://www.bikeroutetoaster.com/Course. ... rse=104217

[GWPOS]

Sounds good. My FTP was at 304 when I last tested with the profile I was using with my old stem. This is why I wanted my new profile to be accurate so I can see if I have improved or deteriated since I did Sea Otter. I guess this is where using the IBike can get a little cumbersome. Creating a new profile and then not knowing if it is equal to the older profile. I will say that its benefits do however out weigh the disadvantages. Anyways lets do that GMR ride. I usually test on the Hwy38 just a little above Mentone on the way to Big Bear. Constant climbing also for at least 30-40 min but the grade can get to around 7-9% in a couple of places which keeps me from being able to get my cadence up over 70-75 hard in those spots.

I will keep using my IBIKE for my rides to see how it feels.

Oh, I use a just put on a cheaper tire for the rear wheel...Kenda Kriterium, and my front wheel has a Michelinn Pro3 service course tire on it.

Clint

[racerfern]

This is the website http://bikecalculator.com/veloUS.html I use to "know" that I have an acceptable profile and I'm not in left field. My FTP is at 225 as of my last field test (46 minutes) and I'm due for another one in about two weeks. If you're at 300 you're looking at about 33 minutes up the climb, so you'll be well rested by the time I arrive.

[GWPOS]

That would all depend on body weight and so forth if I am correct. I weigh 162-164lbs and am 5"8.5" tall. If you a re much lighter than me you could put out less power and still be faster, right??? We will have to get together in the next week or so. It has been 10 weeks since my last test so I need to do one very quickly.

Clint

[racerfern]

I weighed 186 at my last test and being just climbing, height really doesn't affect things. So you will be substantially quicker. I've got a century this Saturday and I'm doing a club ride on Sunday which includes the 8th Stage of the Amgen Tour of California. So I would say June 5 would be the earliest I should attempt a field test. Shoot me an email.