First and foremost this is just for fun and learning new things. If this ends up working and with an accuracy of 10%, no problem. As long as it is showing more wattage than reality, compensating for some weak legs. 

Joking aside, I appreciate your comment. 

For the amplifier, it is just a blunder not adding one, but it could be easily sorted by adding it as a separate module for now. I'm working for my university this summer so I would probably find some cool amplifiers there. I will probably find some good adhesive there as well, but if it lasts a month, it lasts a month.

I haven't put much thought into the project yet, so the asymmetric cranks haven't struck me. Watced your video about it, and it does makes a lot of sense. Im using the 6800 crank myself, so could be worse I guess ;). Going to try to sort it as good as possible, but i could still put the strain gauge inside the crank like TeamZwatt, thoughts? The length of the wire would probably become an issue here. As you mention in your video, the software was for simulating the strain gauge was free, i would probably try this out to find the best position. I do have a pretty accurate CAD model of my crank so. 

I thought of having a third strain gauge between the two existing, but that would probably have little flex. But if you have two sets of two strain gauge one set of the upper section and one on the lower section of the crank. Then I belive it is possible to simplefie the measurements so we can linarize it. Or simulate a lot of spots on the crank arm, find a formula for the upper part and one for the lower part and, use that to compensate the measurements. But it is just a thought and it is possible complete garbage. 

Yet again, great input, and great youtube channel, a little goldmine for this project. 

Worked with strain gages and on several commercial powermeter products. Looks like you're missing either a gain stage or an integrated gain + ADC. You can't just run the strain gage inputs to a nordic and hope to get any result. You need gain of 60 - 200 because we're talking microvolts with traditional strain gages.  HX711 is trash garbage useless, avoid it. TI's ADS series is better with clear documentation and easy to get working. AD have better specs, but only on paper and in reality they come second or 3rd, and Maxim's parts except for the newest are poor. The newest are in high demand, hard to get, and have terrible documentation on how to use them.

As for strain gages, geometry of cranks affect readings, pedal offset does too if using the stages / 4iiiii's / pioneer / shimano on inner surface method a lot. It also leads to the pedal offset twist causing wonkiness in readings for offset, and axial sensitivity. How a company tunes their resistance affects thermal stability. But all that is nothing in comparison to avoid shimano's newest Dura-Ace to 105 cranks. If it' looks asymmetric you lost.

Cyanoacrylate is only good for short term installs. Long term there will be issues if you use it. Proper gage bonding adhesives require high temperature cure (Mbond 600 / 610) or are expensive one time use (AE-41) and proper surface prep and cleaning. Cyanoacrylate is okay for short term proof of concept but it weakens with moisture leading to creep problems. Proper Quality controlled stuff is best (Mbond 200). Off the shelve stuff can work but no gel. Gel superglues are not for strain gages. These will just ruin your gluelines and lead to zero's going off.

My advice I've given almost close to 100 people who've emailed me about powermeter design over the last 8 years. It is 100% cheaper to buy 2 or 3 of the most expensive powermeters in the world than building one yourself and getting it to work. So make sure you're doing this fun, not to save a buck.