Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

% difference between gears ahhhhhh!!!!

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

% difference between gears ahhhhhh!!!!

Old 01-04-14, 01:59 PM
  #1  
osteoclast
Senior Member
Thread Starter
 
osteoclast's Avatar
 
Join Date: Aug 2010
Location: East Coast, Canada
Posts: 91
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
% difference between gears ahhhhhh!!!!

This is driving me insane.

Sheldon Brown's gear charts say that the difference between 53/11 (128.9") and 53/12 (118.2") is 9.1%.

How does he get that answer?

Math incompetent,

G
osteoclast is offline  
Old 01-04-14, 02:07 PM
  #2  
canam73
Senior Member
 
Join Date: Jun 2007
Location: Haunchyville
Posts: 6,406
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Liked 9 Times in 5 Posts
128.9-118.2=10.7

10.7/118.2=9.1%
canam73 is offline  
Old 01-04-14, 03:01 PM
  #3  
osteoclast
Senior Member
Thread Starter
 
osteoclast's Avatar
 
Join Date: Aug 2010
Location: East Coast, Canada
Posts: 91
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by canam73
128.9-118.2=10.7

10.7/118.2=9.1%
Probably the only permutation I didn't try....

Thanks.
osteoclast is offline  
Old 01-04-14, 03:23 PM
  #4  
wphamilton
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 15,280

Bikes: Nashbar Road

Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 2934 Post(s)
Liked 341 Times in 228 Posts
Converting to gear inches is what confuses things. It's just extraneous when comparing gears, where gear ratios are all that's needed.

(52/11 -52/12) = (52/11)/(52/12) - 1 = (12/11) - 1 = 1.0909 - 1 = .091 = 9.1%
52/12

When you think about it, only the rear cogs matter for the percentage increase when all else is the same so you can write it down at the start:

(12-11)/11 = 1/11 = .091
wphamilton is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
colnago62
Road Cycling
263
06-07-17 09:38 PM
largefarva
Clydesdales/Athenas (200+ lb / 91+ kg)
83
12-06-15 07:07 PM
SushiJoe
"The 33"-Road Bike Racing
61
07-24-15 08:28 PM
pkpyro
Singlespeed & Fixed Gear
10
11-12-11 11:02 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.