Project Bike: Kestrel 4000 Bike Fit, prt 2

Think I mentioned I have a friend, Sergio, who has a 2010 4000 in size 52.5.  I already did the size bike fitting and now wanted to confirm with an actual bike that a size 52.5 will work otherwise I will go with the next size up 55.  Sergio is around 5-9 or so and I am 5-11 and change. Yes, I could go the traditional way and just get the 55 and not go thru this drill, but I already have ridden bikes in my normal size. I now want to ride something with a different set up for the experience and change.

The goal of this session is to Retül myself and test ride after making adjusting.

Here are a couple of in the Lab (PedPowerPerform Lab) images before I started changing thing around, (I did swap out the saddle to a Cobb Max for my testing.

I hooked up the bike to the Computrainer to verify pedaling technique and efficiency with my various adjustments. Sergio has his bike set up with Rotor 3D cranks Q-Rings. If you don’t know about the advantages of them you are missing out. I will be building up my bike with a full Rotor crankset which are even better than the Q-Rings. See my previous blog entry.

With the “elliptical” shape of the Q ring, it throws off Computrainer’ average torque angle (ATA) data a little. Note the low 100s/hi 90s degree value. Efficiency is there… being in the 70s

So this is the beginning set up, 90 mm w/ -25 degree stem and massively extended aero bars. I Zined the bike before making any changes so I can easily put back properly and give Sergio his bike measurements. Retul’s Zin is a 3D mapping/digitizing tool that generates full bike measurements based upon 8 or so contact points on the bike. Sergio’s seat tube angle is 77 degrees, a bit laid back for Tri. I have not Retüled him to verify if he is optimized, but he says it is the most comfortable he has ever been… 4:53 at IM FLA a couple of months ago… so it must be working!


The Zin wand.                                       The Retül Receiver.

Zin screen shot.

So now let’s make some changes. Installed the Specialized size stem, set to 100 mm with a rise of -6 degrees. Shorten the extension bars. All for starters.

That’s a NightRider’s Rebel 5.0 computer w/ power to check power output once I go for some test rides.

My final bike build up will using different front end (base bar and extensions) than what’s on the borrowed bike, but these are good enough for basic fitting. I will also building the bike up with Shimano Di2 shifters which shorten the reach a bit more.

Self-Retüling was easy enough; had to put the computer controls/mouse on the aero bars to stop and start the tracking. Putting the LED tracers on oneself was not that bad, the shoulder LEd was the toughest to place properly.

Taking pictures while self-Retüling.

So here are is Retül’s screen image while rider is in action. Green dots are the LED locations with their tracking status, green is good.

And the results in basic data format. Lots of information to get the rider in the most optimal riding position for their riding style and goals.

I interpret the data by looking at values that are out of the Standard/Norms supplied by Retül. See what the trend is saying. Data here looks pretty good, saddle may be a bit low but ankle maximum is good and hip vertical is pretty minimal. I will be using shorter cranks so I know my closed hip angle value will open up.  Since this was a self-Retül session I have to consider that into reviewing the data. Below is a complete fit report.

I have to admit that knee travel is pretty sweet, very linear, no internal/external deviation…. straight power.

Once satisfied with the adjustments made ti the bike, it is time to Zin the bike and print out the report, below.

The main info here is the saddle height, and all the reach measurements. I will be able to use all these measurements to my bike when start to I build it up. I will have to make some slight adjustments with the saddle and aero front end I use, but this gives confidence that the frame size will work.

What is next? go for some test rider!

Have you been Retüled yet? Schedule your next bike fitting at PedPowerPerform Lab.
We also retail Rotor bike Components, Cobb and ISM saddles and Ritchey Bike products along with Gray Carbon wheels, check out the Store.

Slowtwitch did a nice article on the sizing/review of the 2011 Kestrel 4000 LTD.

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