- #1

larry1990

- 6

- 0

**800W 2800rpm electric motor which is rated at 2.8Nm**. I have two issues with my spreadsheets at the moment. Can someone please help?

**Issue 1)**I've made a spreadsheet showing how much power is needed to go up various degrees of incline at a constant 5mph. I've decided to design my bike to go 5mph at 1 degrees. I've now been asked to show how speed varies with angle? I'm expecting a stall angle, but my results don't produce it :(. How can I show speed varying with angle whilst also following my initial specification of going up 1 degrees at a constant 5mph? How much speed will this be on a flat 0 degrees? I'm expecting an 'n' shaped graph, but keep getting a 'u' shaped one.

Here is my spreadsheet on various angles and power needed for constant velocity: http://prntscr.com/a77lym

Here is my attempt at speed vs angle: http://prntscr.com/a77lka

**Issue 2)**Gear ratio. Since the friction wheel will be attached to the shaft of the motor, and it will be driving the rear wheel, the friction wheel will have the same rpm as the motor (2800rpm). My bike wheel is 26inches. If I want the wheel to travel at 5mph. How can I work out my gear ratio? I made a few attempts, but the diameters seem too large. How does torque come into it? Also, if I gear for 5mph, would I be able to go at 10mph with this gearing? or should I change my 5mph specification to 10mph instead?

Here is my attempt at gear ratio: http://prntscr.com/a77mb0

Thanks a lot for viewing and your help in advance guys.