How many sprockets can I fit on a crank? So, I have a pair of ambidextrous shifters on my bike. In other words, both shifters are ten-speed so that you can change the "handedness" of your handlebar if you want. This got me thinking, they could also be used for a 10x10 drivetrain.

So, how many speed chainring is achievable with reasonably off-the-shelf components, and what (if anything) would stop me from building a 100-speed bike, and at what point?
4 chainrings seems to be the feasible limit: 

http://abundantadventures.com/quads.html

However if you add an internal planetary gear setup, A 100 speed might be possible if not practical. Here's a 63 speed bike. 

https://sheldonbrown.com/org/otb.html

There are internally geared 2speed front axles. 

https://www.alphabent.com/internally-geared-cranksets

So in theory 8x is possible on the front, 12 on the back gets you close to 100. You could go 14 in the back with a Rolhoff hub and get over 100. 

I suspect such a bike would self-destruct in a very few miles though. Internal gear systems aren't engineered for the kind of forces that gearing could generate.