Saturday, October 06, 2007

Breaking the Hour Barrier with Geometry

When I modified my TT bike setup a couple of months ago, I pushed the saddle back and lowered the bars a little. It was more aero, but it bothered my back and I didn't feel any more powerful (I thought I would with the saddle further back.)

Here's my July position with angles depicted:

Notice the 87-degree hip angle. That's too acute according to TT position experts - and I could tell that it was too acute becasue my back hurt after a hard 90-minute effort and I didn't feel powerful.

My latest position feels super. I'm as powerful as on my road bike and I'm lower and more aero than I was in the previous setup. Even though I lowered my bars about 4 cm to achieve the second setup, moving the saddle forward about 6cm actually opened up my hip angle and allowed me to breathe better. The 90-degree hip angle and the closer-to-90 shoulder angle also both feel more powerful.

I won't mess with my position much more, because this one works. This summer's position changes have lowered my 40K TT time from 1:04:30 to about 59 minutes, even though my road bike Functional Threshold Power has barely changed. That kind of improvement is worth the effort.