What size are the chainrings?

Good point. Mid-compact 52-36 chainrings

Is the spyder five arm or four? Do you have to use these cranks with their BB?

Spyder arms:
The spyder is five arm (that's all that the C1 powermeter are compatible with). Having said that, Lighting spyders are removable and replacable with an number of different spyders (https://www.lightningbikes.com/...et=0&sort=normal)

BB compatibility:
You can use a variety different BB's with this (i.e. you are not limited to using Lightning brand BB's). The spindles seem to be the same length of current BB386/PF30 cranksets. I was most recently using the cranks with a praxisworks BB30 to PF30 conversion bottom bracket (shown here). There are also cheaper alternatives, such as this BB from aliexpress, or just getting BB spacers/adapters for a BB30 frame.

Of course, the listing includes Lightning's BSA30 BB for standard eglish threaded frames, but you could also use the Rotor BSA30 BB.

bump for price drop.

Sorry for all the questions. Looking to purchase for the wife's bike. She has a Specialized Shiv, would she need a new bottom bracket? She has 50/34 rings, does the C1 work with these? Her bike is all black, no logos, can you remove the logo from the crank arms? Thanks.

Regarding your wife's Shiv: It all depends on what crank she has in there right now. If she has a Shimano crank (24mm spindle), then "Yes, the bike would need a new BB". If it's another brand of crank with a 30 mm spindle then, then "no, the bike should be ready for this crankset with a 30 mm spindle".

I have already removed the lightning logo from the cranks (it's all black).

While the C1 can accept different spec'd 110BCD chainrings (i.e. 50/34) the FSA chainrings on it are actually a '1-piece' unit and you can't separate the big ring from the small ring. I haven't seen anything like that on other cranks, nor do I think you could easily swap the rings from the shiv.

Bump for edits and last price drop.