Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old July 30th 15, 01:27 PM posted to rec.crafts.metalworking
external usenet poster
First recorded activity by DIYBanter: Jul 2015
Posts: 37
Default OT My simple electric bike

On Thu, 30 Jul 2015 00:46:26 -0400, Ed Huntress

On Wed, 29 Jul 2015 23:24:58 +0000 (UTC), John Doe

Took it out in sunny afternoon 98F weather for a 6 mile trip. The 20V
5AH battery shows one out of three bars remaining. Drill got hot but
there was no performance change.

This is really interesting, but I'm having trouble with some of the
numbers. Say the "two bars" consumption equals, roughly, 3 A-hr. At 20
volts, we have 60 W-hr. Just guessing here, but say you travelled that
6 miles at 12 mph.

That means the drill was drawing an average of 120 W for a half-hour.
Let's be generous and say that the system efficiency is 80% from
storage to power at the drill shaft. So, given chain and friction
losses at the tire, you have 1/8 hp driving the bike.

Will that be enough to move you at 12 mph? I'm not familiar with the
actual power consumed by these bikes, but that sounds low. Am I
missing something?

1/8th H.P. is about 90 watts. The average person can do about 3 MPH
using 60 watts. Wind resistance goes up at a square of the speed. The
usual calculations show that an average person riding at a steady 16
MPH on level ground requires about 116 watts. 22 watts to move the
bike and 94 watts to overcome wind resistance.

And of course, weight of bike and rider, tire pressure, type of
pavement, any variation from perfectly level all change the power


John B.

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
OT My simple electric bike SteamboatEd Haas Metalworking 1 July 28th 15 07:12 PM
Electric bike? Here, have this Grimly Curmudgeon[_3_] UK diy 13 May 16th 12 04:40 AM
OT, semi, with metal content. my electric bike trailer Bob in Phx Metalworking 3 June 21st 08 10:01 PM
Upgrading childs electric bike - part 2 Alan Campbell UK diy 1 July 27th 03 06:39 PM
Upgrading childs electric bike Lee Blaver UK diy 9 July 24th 03 12:55 AM

All times are GMT +1. The time now is 11:28 AM.

Powered by vBulletin® Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Copyright 2004-2021 DIYbanter.
The comments are property of their posters.

About Us

"It's about DIY & home improvement"


Copyright © 2017