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


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 08-01-08, 10:04 AM   #1
tommyd49
Senior Member
Thread Starter
 
Join Date: Aug 2007
Location: Cambridge, UK
Bikes:
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Help with front shifter!

On my MTB I am having the problem with the front shifter that it won't shift in to the top chainring without putting a ton of force in, so much that i can only shift it with my right arm, I don't have the strength in my right arm. Ages ago when I first started having this problem I sprayed WD-40 on it but that made it so the part you move with your hand slid over the actual shifting mechanism (this is a Shimano twist shifter BTW). I figured there are three possible causes:

1. This only started after I converted from 42 teeth to 48 teeth with a SRAM front derailleur. Is this because shifters designed to work with 42 tooth cranksets can't generate enough movement to get up to a 48 ring?

2. The shifter needs taking apart and servicing

3. The shifter is just buggered and needs replacing

If any one has got any ideas they would be much appreciated.

Here is a picture of the shifter if that helps

Image017.jpg

Last edited by tommyd49; 08-01-08 at 10:44 AM.
tommyd49 is offline   Reply With Quote
Old 08-01-08, 10:25 AM   #2
robtown
Muscle bike design spec
 
robtown's Avatar
 
Join Date: Oct 2004
Location: Sterling VA
Bikes: 70 Atala Record Proffesional, 00 Lemond, 08 Kestrel Evoke, 96 Colnago Master Olympic, 01 Colnago Ovalmaster, 76 Raleigh Gran Sport, 03 Fuji World, 86 Paramount, 90 Miyata CF, 09 Ritchey Breakaway CX, Bianchi Trofeo, 12 OutRiderUSA HyperLite
Posts: 3,668
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Just a guess - but with the extra 6 teeth could your chain be too short? I've had a RD stretched all the way out because of a short chain and it exhibited the same behavior.
__________________
Korval is Ships
See my Hyperlite 411 it's the photo model on OutRiderUSA web page
robtown is offline   Reply With Quote
Old 08-01-08, 10:45 AM   #3
tommyd49
Senior Member
Thread Starter
 
Join Date: Aug 2007
Location: Cambridge, UK
Bikes:
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Don't think so: I installed a new chain and sized as it told me to on Sheldon Brown's website.
tommyd49 is offline   Reply With Quote
Old 08-01-08, 12:10 PM   #4
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Bikes: Trek 5500, Colnago C-50
Posts: 9,433
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Was the FD properly adjusted for the new 48 ring?
Was the shifter in the small ring position when the cable was re-attached to the FD?
With the shifter in the small ring position there must be no slack in the cable.
You may need to increase the size of the other two chainrings to reduce the differences in sizes.

Al
Al1943 is offline   Reply With Quote
Old 08-01-08, 01:03 PM   #5
tommyd49
Senior Member
Thread Starter
 
Join Date: Aug 2007
Location: Cambridge, UK
Bikes:
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yes to both of your questions - the more I think about it the more I think the problem is with the shifters.
tommyd49 is offline   Reply With Quote
Old 08-01-08, 04:33 PM   #6
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Bikes: Trek 5500, Colnago C-50
Posts: 9,433
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by tommyd49 View Post
Yes to both of your questions - the more I think about it the more I think the problem is with the shifters.
Was the shifter working well before you changed the big chainring?
Al1943 is offline   Reply With Quote
Old 08-01-08, 04:51 PM   #7
tommyd49
Senior Member
Thread Starter
 
Join Date: Aug 2007
Location: Cambridge, UK
Bikes:
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yep there weren't any problems like this before
tommyd49 is offline   Reply With Quote
Old 08-01-08, 06:54 PM   #8
Bill Kapaun
Senior Member
 
Bill Kapaun's Avatar
 
Join Date: Feb 2007
Location: Mid Willamette Valley, Orygun
Bikes: 86 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds.
Posts: 9,271
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Did you raise the FDER for the larger ring?
Have you backed out the H screw a bit (like a 1/4-1/2 turn). It's unlikely the new rings have EXACTLY the chain line as the old. If they sit out 1/2MM too much, it's still too much!
Bill Kapaun is offline   Reply With Quote
Old 08-02-08, 01:26 AM   #9
tommyd49
Senior Member
Thread Starter
 
Join Date: Aug 2007
Location: Cambridge, UK
Bikes:
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Well, I put a new front mech on when I upgraded, and set it up from scratch then
tommyd49 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 12:23 AM.