I have both (Powetap annd CT). Here are a couple of toughts:
I live in a cold climate. I had a coach last winter (Oct-Apr) that created monthly training programs for me on the Computrainer, it was mostly ergo sessions (with the Computrainer Coaching Software) with weekly 3D rides (TT).
If you have specific goals, short summer, a mind that can appreciate Computrainer sessions (not everybody enjoys) I don`t think there is a more efficient tool to target training sessions and measure progress.
I don`t race. My goal was to gain power during the winter to be able to do tougher rides in the summer. It worked. I got absorbed by the power data and bought a Powertap, but this summer I`m not really trainning per se, I am just pushing myself and doing tougher and tougher rides every week so the Powertap data is just an "after the fact" bonus... but for the type of riding I do I could pretty much measure my hill climb times and get a sense of the improvements (or lack of).
It is possible to use a Powertap on a non computerized trainer and create training sessions "similar" to a CT.
Right now the weather is nice and youd could not get me to do computrainer sesssion. They were mentally easy last winter ... and impossible this summer... I get my endorphins outside. If you live in TX... I suspect riding outside might be more enjoyable than inside almost all year round.
CT will shine :
- If you have the room to install it
- If you have a second bike that can be permanently setup on the CT
- If you have an extra computer or a laptop to set it up with.
- If you add audio-video entertainement to your sessions
- If you live in an urban area and want to avoid dangerous or unpleasant roads.
- If your winters are long
- If you have a coach that knows how to create training programs around it
- If you train alone and tend to cheat/easeup when riding outside... an ergo session on the CT does not allow cheating
Splurge ...
... get both !