Playing with my bike fit
I just spent a little over an hour working on my bike fit. I had a Retul fitting a couple of months ago and had a bad experience (I'm sure I'm the anomaly). The Retul guys here in Italy were very new to the system and had never seen a speed concept before. I'm pretty sure they didn't even know the bike existed before mine came rolling into their shop. This was also their first Tri bike fit. There were all kinds of adjustment issues at the fitting and I came away with a sub-optimal position (22 degree torso angle, hips super wide open).
I decided that I would do some experimentation prior to getting a TTbikefit.com fitting that I plan on doing in a couple of months.
I read the bike fit ebook, and looked at a few other resources online for my references.
The method that I used involved setting up a camera to capture video of myself on the trainer. I did a 15 minute warm up to get some blood into the legs and get a more realistic position on the bike under load. I then put the video on my computer and used an on screen protractor that I had from school (runs you $30 for the program otherwise) to take all of my angles. I actually took still from the video instead of static photos of my position to get a better view of what my body was actually looking like while pedaling.
I then made adjustments to get position and angles that I thought were more comfortable and optimal for power production and aerodynamics. The primary adjustments involved a major drop in the aero bars, seat moved forward slightly and angled a bit downward at the nose, raised seat, and aero bars moved a bit more forward. This was a general clockwise rotation of my overall position.
My final results were a knee angle of 31.1 degrees, shoulder and elbow angle of 87 and 88 degrees respectively, and a torso angle of 6.6 degrees while maintaining a hip angle of 97 degrees (torso through hip to ankle).
The research involved over the past couple of days has opened my eyes to my fit a great deal, and I definitely entertained myself this afternoon. I'll include a few screen shots of my position with the protractor that I used to take measurements as soon as I get them hosted.
I welcome any critiques of my methods of position as I'm definitely new to doing this and I'm trying to gain some knowledge about bike fit. Thanks.
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Comments
Do you have a picture with your foot at BDC in relation to your body? In other words, in the picture you are at least 45 degrees past where your leg is fully extended. A picture where your crank is at the same angle as your effective seat tube will show your knee angle at it's most extreme position.
I woudl say you are now at the point where fitting becomes and art and not a science. There is no exact angle that is perfect for everone so you may find a few mm either way will be more comfortable, allow you to put out more power, or cause your hips to rock less and your body to be more stable. If would set this saddle position as your baseline and expeirment a little with movign the seat 2mm up and 2mm down and see what it feels like.
Based on the description of the fit you got from the bike shop, you are in a very different position now. I would just ride it for a bike and then re-assess. I don't know when IM Switzerland is but I believe you have a while still to work it out.