October 1, 2014
There are numerous reviews of the 510 but they do not really cover using it with a power meter, and an SRM in particular. Recent fireware updates have addressed the ability to stop auto zero offset and have added some really useful metrics that are incredibly useful in training.
If you want an overview of all the features of this device then I'd recommend taking a look at DC Rainmaker's Garmin Edge 510 in-depth review.
When I first got an SRM power meter I opted for a PC 7 head unit. If I am honest the main reason was to get that pro look because at the time they were ubiquitous in the peloton. The PC 7 does the basics very reliably but no GPS is a real shame as it means so social sharing of ride data. It also has no ability to store bike profiles, so as I use several bikes this means the hassle of pairing before each ride. Finally, the user experience of the PC 7 is not brilliant, with quite a few functions being accessed by pressing a combination of buttons. The obvious move was to switch to a Garmin, but this had one fatal problem...
In his blog post Three, Two, One, Zero Offset Alex Simmons highlights the problem with data accuracy that you can get if you have a head unit configured to perform automatic zero offsets. When it was originally launched the 510 had no way to disable automatic zeroing, hence making it useless for SRM owners.
However, as you can see on the Garmin 510 firmware updates page, with version 2.80 they added "the ability to turn SRM power sensor auto zeroing on and off". Note that this feature has not been added to the 500. This setting is accessed via the bike profile (so needs to be set on each bike).
Carrying out manual calibration is quick and simple on the 510, you can access the option by tapping the top part of the initial ride screen which takes you to a screen showing all paired sensors. I have found the calibration setting can be a little hit and miss to start even when the unit has picked up the power meter and it has been woken up by spinning the pedals. Simply backing out and then hitting calibration again after giving the pedals another psin seems to do the trick.
If you try searching for reviews on the 510 with power meters you will find plenty of results that report dropouts and other issues. I think most of these were on firmware versions les than 3.0 and I have seen no such problems (my device is on 3.20). I have not done any side by side recording against the PC 7 but the data has been not been noticeably out of kilter with previous rides.
One of the best things about the 510 with power is the big range of metrics that it provides. I have found the ability to display normalized power, intensity factor and TSS during rides to be incredibly useful. It helps ensure that a ride is on track which can be hard to do just on feel and monitoring your current power. These metrics are all available for both the whole ride and current lap.