I’ve fitted my powermeter wrong, haven’t I?

[stongle]

So, yesterday was an exciting day in the stongle household. My Quarq arrived (finally); with the little cranks (toof recommendations from the Stages thread). We took off the Rotors and Q’s to replace them with the much more aesthetically pleasing Quarq Elsa and Praxis rings (tart alert its more in keeping with the bike’s colorway / theme). Anyway, I was pretty confident that due to the Tube Strike; I’d be blasting commuters into the weeds on the way home with 900+ watt efforts of the lights (I stop a few hundred yards up the road to receive celebratory knickers)..

Well, to cut this long story short; I was a little miffed when the max power I registered on the Garmin was about 240watts; and when riding @ 25mph on the flat I was recording 45-90 watts (solo; not in the armchair). This seems a tad low, despite sacrificing myself on the altar of aero and being a bit pointy on the bike. Is it likely I’ve installed it wrong; or should I look at the Garmin options (3s average)?

Is there any other quirks I should be aware of (running in period)? Or maybe just a reset? Anything electronic or mechanical I’d describe myself as a total goober with – so I’m hoping the fix is easy!

[okgo]

Talk me through how you installed the chainrings?

Also what you did in the garmin prior to riding...

[esuuv]

Did you calibrate it - i've no experience with that unit but on my stages its pedal all the way to the bottom, unclip and run a calibration on the Garmin.

[fromage]

My Quarq takes a few rides to settle down after installing new rings but still isn't far out when settling down and is helped with sprints in both little and big chainrings.

Also make sure that all chainring bolts are torqued correctly, I torque mine to 12NM.

Also make sure you calibrate/zero it on the garmin before every ride (ideally before or after 10 minutes).

[stongle]

Thanks Chaps. I torqued the bolts per the required settings. Can't remember exactly will check manual.

Didn't do anything to the Garmin; before riding it (although I have now set it to the 3s average power).

I'll try the sprints. It did feel a bit like when I was pushing down harder / climbing the power seemed closer to perceived output - but when cruising along on the flat (lower perceived effort) power went waaaay down.

I'll try the resets & sprinting tomorrow and see what happens (subsequent responses liable to be expletive loaded).

[okgo]

You have to calibrate before every ride, otherwise the numbers will possibly not be correct, not sure if it has the temp dispensation built in but taking it from a warm house to cold outside normally needs a calibration too if not.

[neenaw]

okgo said:

You have to calibrate before every ride, otherwise the numbers will possibly not be correct, not sure if it has the temp dispensation built in but taking it from a warm house to cold outside normally needs a calibration too if not.

I find the same thing when its particularly warm or cold outside with my Quarq, the calibration number can differ quite considerably once the temperature's steady.

You can also calibrate it when you're out riding by back pedalling about 5 or 6 revolutions then not pedalling for 5 seconds or so.

[Magic919]

My wife leaves her bike in the garden for a few mins and then calibrates (every ride). I expect this helps accuracy, but wouldn't think it would be a huge percentage.

On Okgo's advice I took great care to torque the chainrings and got them within a few hundredths of a NM variance.

[PorkRind]

Do you mind providing what parts you used to get this setup - I'm a novice when it comes to this pm stuff but would be interested to see the costs involved/setup .

[Magic919]

I had to replace the bottom bracket, swap the chainrings to the Quarq and then fit the Quarq crankset. About a grand.

[stongle]

Quick update, and thanks to those with the advice. Everything now appears to have settled down, and do as the advice above. calibrate before every ride, and do the quick spin ups. It certainly feels consistent with my Watt Bike power numbers. Its such an aid to climbing, I should've bought one ages ago.