getting a regular bike after my battery fails?

[Stefan Mikes]

What I need is a calculator that tells me that at 240 pounds with gear and my bike weights say 35 pounds, what gearing do I need to get up a 18% grade, putting out say 200 watts and 400 watts. That will really help with the gearing. A triple on front would take care of it too.

Bike Calculator

Useful calculators for estimating your speed on a bicycle velocity from various parameters.

bikecalculator.com

Bike Gear Calculator For Cyclists | BikeCalc

bikecalc.com

You need to run both of them in sequence.

With the input of 200 W, you can only achieve 1.88 mph, which is impossible to maintain.
If it is 400 W, then the speed would be 3.75 mph, and probably you could barely maintain that speed. (18% grade is a killer).

Let us assume you could maintain the stability at 3.75 mph. So now we get to the other calculator, this part:

Bicycle Gear Speed Cadence Table | BikeCalc

Calculate cycling speeds at a specified cadence given chainring, sprocket, tire and wheel sizes.

bikecalc.com

Assume your 2x chainring is of a gravel type, 30/46T. Again, if that's a 2x gravel cassette, the granny gear would be 36T. Let us eventually assume a typical wheel size for a gravel bike:

You can do it with a 30T front chainring and the 36T granny gear of the 2x system when you are out of saddle and pedalling at 55 rpm.

Next attempt. 1x, 32T chainring and 51T granny cassette gear. Let us assume you pedal at 70 rpm:

You need to pedal at around 70 rpm while inputting 400 W. The gearing can be achieved with a 32T chainring and a 51T granny gear, for example with an 11-speed Shimano CS-M5100 cassette or one of SRAM 12-speed MTB cassettes such as the 1275.

Note: The speed is independent of the gearing. To climb a specific grade at a specific speed, you need to input a specific power (calculator 1). When you know the speed, you can find a gearing that allows riding at that speed and at given cadence (calculator 2).

P.S. It is the technique @mschwett once taught me. I used those calculations before a race where 14% grade climbs were expected. It made me understand I needed my full power e-bike for that race. And an MTB gearing, too.