Rather than start another thread, I will add my recent experience with the Garmin Vector to Merlin's.

We took delivery of the Vector about a week ago and spent last week installing it on my wife's road bike in anticipation of the GMR hill climb race in SoCal. She has a Quarq on her other road bike so she has a long track record of power data and perceived effort at different power levels.

I was installing the PM on the fly as we were on vacation in SoCal and the first thing I discovered is that I needed a special torque wrench and a 15 mm crowfoot socket. I have a torque wrench but it does not go high enough for the 25 foot pounds of torque required. After searching, I found the crowfoot socket at Lowes and the thickness of the socket was a perfect match for the pedal clearance. If the crowfoot is too thick, it will not work well.

I found a 0 to 75 foot pound torque wrench at Sears. I wanted a torque wrench with the 25 foot pound reading in the sweet spot of the range. Sears sells several torque wrenches and some go higher in torque but IMO, make getting an accurate reading more difficult at the lower end of the range. Also, one does not want a torque wrench that has too large of a head. If the head is too large, it may not allow the crowfoot socket to fully engage on the pedal.

I followed DC Rainmaker's instructions and read the Garmin info and looked at the videos. I recommend that one reads the entire DC Rainmaker review before proceeding with the installation.

Prior to installation, I checked the Garmin site for software updates and updated my Garmin 500 and 800. I planned to use the 500 for the Vector although the 500 does not have an installation wizard in the software. I also, updated the Vector Firmware by using the Garmin supplied WIFI UBS gizmo. One first has to download the Vector Updater and then pair the UBS gizmo with the Vector pedals. Each pedal is done individually by removing the battery and waiting 20 second and then re-installing it. The update worked perfectly and I set the crank length during the update. I do not think that the 500 sets the pedal length in the firmware.

There are a couple of tricky parts to the installation to get it right. IMO, a torque wrench is required and the crowfoot socket a must. DC Rainmaker has a curve showing error as a function of torque. The curve is pretty flat around 25 foot pounds but greater or less torque causes power data accuracy problems. The other issue is getting the accelerometers perfectly positioned on the crank arm. First, there has to be a space ~1mm between the accelerometer and the crank arm and this is accomplished by adding washers. I used one washer but more may be needed. The other is getting the accelerometer 90 degrees to the pedal. When the pedal is tightened, the accelerometer turns with the torque wrench. So one has to put a 15 degree offset from 90 degrees and then torque to 25 pounds. I used the pic in the DC Rainmaker review and when I hit 25 foot pounds, the accelerometer was at 90 degrees.

Potential problems... Some crank arms may not work due to clearance between the chain and the plug that plugs into the pedal spindle. My crank was a D/A and it was fine. Also, oval chainrings may not work and are not supported.

Before starting up the software, ride the bike and put in some sprint efforts. The goal is to stress the mechanical system prior to calibration. The 800 has a wizard to assist in the calibration but the 500 does not. The first thing that one has to do is allow the Vector to check the angles of the accelerometers. This is done by powering up the Garmin and pairing the head unit with the Vector. One then rides the bike and accelerates from 70 to 90 rpm. During that rpm acceleration, the software will flash a screen indicating success and start indicating power. With the 500 head unit, I did not see a splash screen. After that setup is complete, there is a static calibration with the pedals at 3 and 9 O'clock. The final calibration is a dynamic calibration by pedaling backwards 8 times and the Vector gives another splash screen and you are ready to rock.

Writing this description of what I did was harder than actually doing the installation and the setup. Such is life with documentation.

My wife test rode the Vector and said the power matched her perceived effort.

The next day, the Vector would not perform a static calibration and gave a calibration failed error even though the power readings seemed accurate. I got on the phone with Garmin (I got a CS rep in about 3 minutes) and discussed the problem. He talked with his software support and indicated that the 500 can create a corrupt file the first time it is used with the Vector. I had to do a hard reboot of the 500 and reset all the settings. The Rep stayed on the phone while I did the restart and then with me while I rode the bike and redid the startup of the Vector. It worked perfectly and calibrated. They will have to revise the 500 software to fix this bug. I told the Rep that I did not see the splash screen going from 70 to 90 rpm. He said that it is really fast and most miss it.

My wife used the Vector at the GMR race and it calibrated and worked perfectly comparing past power data to the new Vector data seems that the Vector is yielding accurate data.

Swapping between bikes... Based upon my limited experience, this seems totally reasonable and should not take a lot a time (a few minutes) but the torque wrench and crowfoot socket are a must IMO. There may be issues with crank arms and chain rings and the crank arm length (if different) must be reset each time and it is unclear is one needs to do that using a computer or can be done with certain head units.

We deem the purchase and installation a success and certainly equal to or better than the experience we had with Quarq and Power Tap. YMMV.