Am I missing something here 
If you drop to 46 on your left side, which is where the PM measures, then the PM simply doubles it to 92 so not 3-5% really.
Say you drift on effort over the last 40-60km ā¦
Youāve targeted to do 225W, but your PM is telling you 207W, so you increase your effort until it says 225W, but you might actually be doing 245W.
So youāve overcooked it. Massively.
Yes I would be close to ~8% off at my absolute worst on those numbers, but what I meant was 99% of my riding Iād be within 5% (and the majority within 2%).
The only time Iāve seen something like 46.5-47.0 on the Left is in the final minutes of something like a VO2 session, not prolonged 50km.
But if youāve know that your L/R changes in different conditions, then thatās when it becomes less useful. In my example I wouldnāt know if I was losing watts as a I fatigue or just shifting towards my right leg.
I didnāt realise until after Iād ordered it, but my new bike comes with a SRAM crank-based power meter as standard.
Iāve never used a power meter on the road before, only on Zwift and a wattbike. I doubt if itāll be much more than another number on the Garmin for me, but itāll still be interesting to see what my outdoor power looks like 
Itās not one of these that you need to pay to actually use it?
Let us know 
IMO itās only interesting to review for racing and workouts. Iād say I benefitted from practising steady (ish), tempo power on climbs.
Iām trying outdoor workouts a lot more at the moment.
Itāll be staying deactivated for now at least if it is . Itās a bonus feature for me and not one that Iād pay extra for.
I wouldnāt have thought so. Itāll be a quarq under the hood too (even if officially sram branded) so should be about as good as they get.
Surprises me youāve not had one for outdoors before. For random road riding, Iād agree with others the numbers arenāt critical but there are points in a ride when they help like others have said. And over time, I do think having the data better evaluates cumulative stress and trends.
Any experts have an opinion of Garmin Rally vs Assioma? Both dual sided, same price and both SPD-SL. Bike computer and watch are both Garmin if that makes a difference.
Assiomaās are better.
Cooler kids buy them.
Sciencefact
If you have other Garmin stuff, Iād go Rally especially if you can get them the same price. Thatās what I have.
Ultimately, Rally looks way cleaner than the Assiomaās in my opinion, and if youāre going for spd-sl then the Assiomaās is a bit of a bastardisation to make them. Theyāre not the same Keo equivalent pedalā¦the Q-factor is more as they sort of fudged the old tech into a spd-sl pedal body. Plus, the old issues of torque wrenches for Vector is gone with Rally.
As ever, DCR has all the full details. But the one thing Iād say there is the priceā¦back when he wrote that, Rally was c50% more expensive. That was always the Assiomaās plus point. If price difference isnāt there, I donāt see why youād go for them.
See above
Why do you want power?
Send me Ā£400 and Iāll send you some numbers after every ride for you to look at.
Sorted. 
Youāre going to do some rides and get a number.
Look at it.
Shrug. And repeat.
Waste of money.
A fair question
Excessively presumptuous!
Why do you want an overpriced tshirt with Palace written on it? Or whatever the brand of the day is?!
So many Whyās! 
To keep Lev in business
Supreme bought out by Luxotica yesterday.
Anyways, this is power meters for idiots.
Idiots shouldnāt waste money on power meters.
Ride your bike. Have fun. Donāt be a slave to the numbers. Learn how to pop a wheelie. Do a sweet skid coming into T2. Drink some beetroot juice and sit in the garage with the door closed and engine running. Itās all good.
Not sure how one why is so many? 
Well my why is why canāt you ride to numbers, build structured plans to improve if you gain happiness and satisfaction from goals and stuff. Why is it one or the other?
I have a power meter (as do you! ) and it doesnāt diminish my fun.
I wear a garmin on long trail runs. I keep an eye on pace and stuff. But it doesnāt take away my enjoyment. But it does help me improve.
Itās all about the grey my Poetic friend.
Ok, Iām sorry, Iāve ditched the idea of buying a power meter, if you can send me bank details Iāll set up a direct debit for the power numbers. If you could make my normalised power for Thursday night club TTs in the mid-300s it would be appreciated. 
Iāve used the money I saved to get a new bike instead, itās a Sledgehammer with shocks, pegs and Iāll be taking it off some sweet jumps later on. 
I always liked one of Alex Dowsettās quotes when talking about kids cycling, āDont buy a power meter, buy a BMX insteadā