I have the Garmin Vector 3s Single-Sensing Power Meter. There are a ton of options out there in terms of power meters not only due to the different brands but also because they can be placed in five places on the bike:
- The rear wheel hub
- The bottom bracket/spindle
- Chainrings and crank spiders
- Crank arm
Because I am vertically challenged and my crank arm is shorter than normal, I opted for the power meter on the pedal. I also chose this option so that I could swap it from my road bike to my tri bike or vice versa easily. The double-sensing power meter is a bit of an overkill in my humble opinion and is also more expensive than the single-sensing power.
All of that said, I wouldn’t rely solely on power based metrics. If it is in your budget to have a power meter, I would train using heart rate, power, and perceived exertion in case one of those fancy gadgets runs out of batteries or fails to function during the race! That way you’re always covered! If a power meter is not in your budget, don’t panic! Heart rate based and perceived exertion will get you to the finish line too!