Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 07-16-08, 03:44 AM   #1
OldiesONfoldies
Small wheels ARE better!
Thread Starter
 
OldiesONfoldies's Avatar
 
Join Date: Sep 2006
Bikes:
Posts: 362
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Help me w math - downsizing chainring 52 to 42

Dear folks,

I've changed the chain ring of my Speed 8 to a smaller one, 52 to 42. Wondering what is the effect on the gear range. Can someone help me calculate the new gear range with this mod? Does this reduce the gearing by 25%? The original cassette 11 -32t remains.

Speed P8 31-91' (with 52 chain ring)

42 chain ring = 24 - 69 (is this correct?)

Hope to do some serious climbing with the new mod. Many thanks!

OnF
OldiesONfoldies is offline   Reply With Quote
Old 07-16-08, 03:59 AM   #2
bendembroski
My legs hurt
 
Join Date: Apr 2008
Location: Farther behind you than I'd like to be
Bikes: Vaya, Brompton, '73 Schwinn Super Sport, Cresswell Fold-it, '81 Trek 610
Posts: 683
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
http://www.sheldonbrown.com/gears/

This should tell you all you need to know.
bendembroski is offline   Reply With Quote
Old 07-16-08, 05:21 AM   #3
jur
Senior Member
 
Join Date: May 2005
Bikes:
Posts: 6,833
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 24 Post(s)
New gear range = old range * new ring / old ring
= 31-91" * 42 / 52
= 25-73.5"
jur is offline   Reply With Quote
Old 07-16-08, 06:45 PM   #4
OldiesONfoldies
Small wheels ARE better!
Thread Starter
 
OldiesONfoldies's Avatar
 
Join Date: Sep 2006
Bikes:
Posts: 362
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks guys! Glad for the helpful experts here...
OldiesONfoldies is offline   Reply With Quote
Old 07-16-08, 06:48 PM   #5
Wanderer
aka Phil Jungels
 
Wanderer's Avatar
 
Join Date: Apr 2005
Location: North Aurora, IL
Bikes: 08 Specialized Crosstrail Sport, 05 Sirrus Comp
Posts: 7,552
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
You have effectively reduced all the gear ratios by approximately 20%.
Wanderer is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -6. The time now is 07:45 AM.