Hi. I will switching out my current hub-based power meter for the new PowerTap p1 pedals. As a result, I will need to add a speed sensor since the pedals don’t transmit any speed data.
I am sure I can figure this out by myself, but I thought the reliable Slowtwitch community could help me faster: I have the first generation Trek SC9 with the duotrap thingy built-in. Do I just need to add a magnet to the spoke (and then pair it with the computer), or do I have to put something in the trap itself?
Thanks,
David
P.S. I will be using that 50% coupon that PowerTap is offering for Kona people. There is a thread on this elsewhere in the forum. People have challenged them on the marketing of this, but for this one customer, it worked. I wouldn’t likely making this switch at this time without this offer…
Assuming you have the actual Duotrap unit installed (in lieu of just the blank off plate that the SC comes with), yes - you just need the spoke magnet on the rear wheel.
The Duotrap sensor also needs a CR2032 battery.
Alternatively, you can always use the GPS on your Garmin, etc. for speed, but you’ll need the wheel sensor for the best accuracy, or if you do aero field testing.
If you have a Duotrap you just need to put a magnet on a spoke and pair the Duotrap with your computer. Question is…do you actually have a Duotrap sensor or just the Duotrap “plug” that ships stock with the bike? The latter would say something like “Duotrap-ready” and doesn’t have the actual sensor pod that extends along the inside of the chainstay. See picture below…the one in front is the plug, the one in back is a Duotrap sensor…which can be ordered through any Trek dealer or direct from Trek here.
Unless you’re using a Garmin watch (or an older computer) the head unit you’ll run with the P1 pedals will likely have GPS (and consequently mph) built in. The P1s also measure cadence so I can’t think of a good reason to use your duotrap.
I have both a Garmin Edge 520 and a PowerTap Joule GPS. I find that using the GPS for speed is ok, but not nearly as accurate as the data that comes off of my hub, plus it’s a little delayed (not as real time as the hub).
Do you have better experience with using GPS for speed measurement?
yes…that’s the only Duotrap version which will fit in your bike…same one for both generations in fact…it’s different from the Duotrap S which is the version for our other current road bikes.
