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 02-24-10, 04:52 PM   #1
brsboarder
Senior Member
Thread Starter
 
Join Date: Jun 2006
Bikes:
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Derailer Question from someone w/o too much fixing knowledge

So, I have a giant OCR 2 w/ tiagra/105 components.

I just started getting back onto my bike after a long absence (knee surgery and broken foot). I'm riding the bike on a cyclops trainer right now.

Here's the problem:

If I am on the smallest chain ring on the front, and about the 3rd biggest on the back, the chain will sometimes slip into another gear then fall back into place. This happens fairly often, and also happens in a couple other gears as well. In addition, if I am on the middle ring on the front, and the 2nd largest on the back it will sometimes slip as well.

The front doesn't seem to slip, only the back. I'm wondering what type of derailer adjustment I should need to do. Thoughts?

Thanks
brsboarder is offline   Reply With Quote
Old 02-24-10, 04:56 PM   #2
jco1385
Giant Puzzle
 
jco1385's Avatar
 
Join Date: Jul 2009
Location: Alabama
Bikes: Giant Rincon 23.5"
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
probably just a minor barrel adjustment.
jco1385 is offline   Reply With Quote
Old 02-24-10, 05:20 PM   #3
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Bikes: 1987 Bianchi Campione
Posts: 28,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by brsboarder View Post
So, I have a giant OCR 2 w/ tiagra/105 components.

I just started getting back onto my bike after a long absence (knee surgery and broken foot). I'm riding the bike on a cyclops trainer right now.

Here's the problem:

If I am on the smallest chain ring on the front, and about the 3rd biggest on the back, the chain will sometimes slip into another gear then fall back into place. This happens fairly often, and also happens in a couple other gears as well. In addition, if I am on the middle ring on the front, and the 2nd largest on the back it will sometimes slip as well.

The front doesn't seem to slip, only the back. I'm wondering what type of derailer adjustment I should need to do. Thoughts?

Thanks
http://www.parktool.com/repair/readhowto.asp?id=64

Could be as minor as #2 suggests or more than that. Easiest way to do this is start from step #1. A lot of things can cause the symptom you're describing. You'll need to do a bit of legwork to understand the type of adjustment and problems.
operator is offline   Reply With Quote
Old 02-24-10, 05:49 PM   #4
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,011
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 391 Post(s)
As the others said, it could be a barrel/trim adjustment, or could be more complicated, but you might as well start with the simplest and either solve the problem or eliminate it before looking farther.

The last section of housing ends at an adjuster on the RD. If you turn it outward, it lengthens the housing, effectively shortening the gear wire, and moves the RD inboard. Turn it in and the opposite happens.

Leave your bike on the trainer, but lower the resistance unit so the wheel spins freely. Put your bike in any gear and eyeball the chain and cassette from the back. See if it's feeding perfectly centered onto the sprocket. If not turn the adjuster until it's centered then run through the gears. Ideally it should be smooth and quiet in each gear and shift equally well in either direction. If it shifts inward better than outward turn the barrel in a bit, or out if it shifts out better than in. Since you're new at this feel free to experiment, trial and error with 1/4 turn adjustments until you dial it in.

When you're finished, double check that the inner limit is OK by pulling on the bare wire and trying to shift beyond the low gear cog. If the chain goes over the top, tighten the low gear "L" limit screw by 1/4 turns until you cannot make it overshift.

If you can't solve the problem easily this way, it could be a bent hanger, especially if you wrecked your knee and foot crashing this bike.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY 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 04:07 PM.