Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Can't get to shift to smallest cog & skips through cassette

Notices
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.

Can't get to shift to smallest cog & skips through cassette

Old 08-20-20, 10:30 AM
  #1  
the sci guy 
bill nyecycles
Thread Starter
 
the sci guy's Avatar
 
Join Date: Mar 2013
Location: Houston TX
Posts: 3,014
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 636 Post(s)
Liked 163 Times in 88 Posts
Can't get to shift to smallest cog & skips through cassette

It's a GRX derailleur. It'll shift down to the 2nd highest, but then even though the shift lever pushes over, nothing happens. It will go all the way up to the big ring, though. It also skips around a lot as you move up and down through the cassette - it won't stay on certain cogs or will want to bounce back and forth between them.
It all started because I tweaked the barrel adjuster a tad as it was initially skipping a tad on a few and sounded a little clicky like it wasn't just right. Then it snowballed from there and it's all gone to hell.

halp pls.
__________________
Twitter@theSurlyBiker
Instagram@theSurlyBiker
the sci guy is offline  
Old 08-20-20, 10:36 AM
  #2  
fietsbob
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,599

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,302 Times in 817 Posts
All the engineering done to speed shifting works against you,

if the derailleur hanger alignment and index shifting adjustment, is not spot on.



fietsbob is offline  
Old 08-20-20, 10:40 AM
  #3  
dsbrantjr
Senior Member
 
dsbrantjr's Avatar
 
Join Date: Sep 2010
Location: Roswell, GA
Posts: 7,883

Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta

Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 1269 Post(s)
Liked 707 Times in 498 Posts
It sounds like you need to start at the beginning and use a systematic approach to the issue. Here is a good procedure: https://www.parktool.com/blog/repair...eur-adjustment But as fietsbob suggests a properly-aligned derailleur hanger is the basis for smooth shifting.
dsbrantjr is offline  
Old 08-20-20, 11:03 AM
  #4  
Erzulis Boat
3rd Grade Dropout
 
Erzulis Boat's Avatar
 
Join Date: Oct 2005
Location: Santa Barbara Calif.
Posts: 1,271
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 149 Post(s)
Liked 77 Times in 37 Posts
The classic "Won't go to the smallest cog"- Very common.

Remove the chain, and start from scratch.

You need to get both the hanger interface and both limit screws (high/low) in order first.

There is a trick to the limit screws adjustment. On the smallest cog, you need to actually have the top derailleur pulley go "past" (as in farther outboard) than directly below (in line) the cog. Typically, it is about a cog width of outboard offset that does the trick.

The reason that you cannot get into the smallest cog is that due to deflection the chain is fighting itself basically, and even though technically it should work, it simply doesn't!

Align the upper pulley of the derailleur directly in line with the biggest cog however, as this issue only manifests itself with the smallest cog. Once you have both stops adjusted, go through the gears (chain is still not installed) about 10 times to settle everything in, and to triple check.
Erzulis Boat is offline  
Old 08-20-20, 02:19 PM
  #5  
Miele Man
Senior Member
 
Join Date: Jun 2014
Location: Ontario, Canada
Posts: 4,284

Bikes: iele Latina, Miele Suprema, Miele Uno LS, Miele Miele Beta, MMTB, Bianchi Model Unknown, Fiori Venezia, Fiori Napoli, VeloSport Adamas AX

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1164 Post(s)
Liked 727 Times in 507 Posts
Check your cable housing to see if the strands are poking through the ferrule or if a ferrule is missing.

Cheers
Miele Man is offline  
Old 08-20-20, 06:20 PM
  #6  
BoraxKid
Senior Member
 
Join Date: Jul 2020
Location: Parts Unknown
Posts: 356
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 325 Post(s)
Likes: 0
Liked 103 Times in 67 Posts
Originally Posted by the sci guy View Post
It's a GRX derailleur. It'll shift down to the 2nd highest, but then even though the shift lever pushes over, nothing happens. It will go all the way up to the big ring, though. It also skips around a lot as you move up and down through the cassette - it won't stay on certain cogs or will want to bounce back and forth between them.
It all started because I tweaked the barrel adjuster a tad as it was initially skipping a tad on a few and sounded a little clicky like it wasn't just right. Then it snowballed from there and it's all gone to hell.

halp pls.
After you verify that your derailleur hanger is straight, I would undo the shifter cable at the pinch point, reset your barrel adjuster, and follow the Park Tool video instructions for setting up a rear derailleur. This should be the fastest path to restoring your bike to its pre-barrel adjuster change state.

It sounds like you turned the barrel adjuster the wrong way to start with, and now you have lost your reference point for correcting it. The issue of not reaching the smallest cog could be caused by too much cable tension (from the barrel adjuster changes you made), an improperly set limit screw (which you did not mention changing, so less likely), a bent hanger (could have caused the original problem), or some other reasons (cassette precession, wheel not properly seated, play in the hub bearings, etc.). Start with the derailleur setup video and work from there. Good luck.
BoraxKid is offline  
Likes For BoraxKid:
Old 08-20-20, 08:32 PM
  #7  
the sci guy 
bill nyecycles
Thread Starter
 
the sci guy's Avatar
 
Join Date: Mar 2013
Location: Houston TX
Posts: 3,014
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 636 Post(s)
Liked 163 Times in 88 Posts
I didnít want to go all-in and take the chain off and start from scratch since this is a new out of the box bike and I was hoping it would pretty close to all set to ride.

I futzed with it a little more tonight and I got it to shift smoothly up and down the cassette but it still wonít go to the last cog. The shifter paddle pushes all the way but nothing happens. The chain appears to run smoothly through every other gear. The hanger is not bent as far as I can tell.

Iíll check again tomorrow but if I twist the barrel so it skips to the last cog, then adjust it each time moving back up the cassette, will that help?
__________________
Twitter@theSurlyBiker
Instagram@theSurlyBiker
the sci guy is offline  
Old 08-20-20, 09:04 PM
  #8  
trailangel
Senior Member
 
trailangel's Avatar
 
Join Date: Feb 2014
Location: Pasadena, CA
Posts: 4,508

Bikes: Schwinn Varsity

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1718 Post(s)
Liked 437 Times in 267 Posts
Originally Posted by fietsbob View Post
All the engineering done to speed shifting works against you,

if the derailleur hanger alignment and index shifting adjustment, is not spot on.



Align the DR hanger before proceeding. You are wasting your time.
New out of the box is not straight.
trailangel is offline  
Old 08-21-20, 12:03 AM
  #9  
tFUnK
Senior Member
 
Join Date: Jun 2002
Location: San Jose, CA
Posts: 2,699

Bikes: Too many bikes, too little time to ride

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 102 Post(s)
Liked 46 Times in 41 Posts
Check the b limit screw also. Even if it's new, it sounds like either something is wrong (eg, hanger) it it was never adjusted properly to begin with.
tFUnK is offline  
Old 08-21-20, 03:48 AM
  #10  
dsaul
Senior Member
 
Join Date: Jan 2013
Location: South Jersey
Posts: 1,843
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 559 Post(s)
Liked 363 Times in 261 Posts
It sounds like you turned the barrel adjuster far enough out to skip one whole cog, so you can shift all the way up until it hits the limit but you run out of clicks going down the cassette. Shift down until the shifter doesn't click any more and then turn the barrel adjuster in(clockwise) until the chain shifts to the smallest cog and start from there.

In my experience, the derailleur hanger has to be bent pretty badly to prevent you from being able to get it to shift correctly. As long as it is not noticeably bent and it hasn't taken a recent hit from a fall, its probably not the problem
dsaul is offline  
Old 08-21-20, 06:56 AM
  #11  
trailangel
Senior Member
 
trailangel's Avatar
 
Join Date: Feb 2014
Location: Pasadena, CA
Posts: 4,508

Bikes: Schwinn Varsity

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1718 Post(s)
Liked 437 Times in 267 Posts
In my experience, when the derailleur hanger is bent very slighty, it will prevent you from being able to get it to shift correctly.
trailangel is offline  
Old 08-21-20, 08:07 AM
  #12  
Erzulis Boat
3rd Grade Dropout
 
Erzulis Boat's Avatar
 
Join Date: Oct 2005
Location: Santa Barbara Calif.
Posts: 1,271
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 149 Post(s)
Liked 77 Times in 37 Posts
Ok. You do not want to remove the chain. Fair enough. If the limit adjuster isn't set properly, NO amount of playing with the barrel adjuster will fix your issue. And, if it's a barrel issue, this will get you back to ground zero. Win/win!

1- Run the shifter all the way down until it won't "click" any more.

2- Loosen the barrel adjuster so that the cable is slack between where the cable housing is anchored to the derailleur body and the clamp for the cable.

3- Go back to the lever, and try to click it down some more. IMPORTANT.

4- Start rotating the cranks, and see if it still doesn't want to engage the smallest cog, we are almost done!. At this point, it will either not drop down at all, or start going "Gung...Gung...Gung" (in a metallic fashion ) Like it wants to drop down, but it just won't.

5- Find the limit screw on the derailleur that allows the body to go farther outboard (away from the bike). Start by rotating it about 1/2 turn, and rotate the cranks again. If it is still not there (as in going into the smallest cog), allow more movement outboard until it hits the stop. KEEP THE CABLE SLACK!

6- Once again, go back to the shifter, and click it all the way down. We are just making sure again.

7-IMPORTANT. Make sure that the derailleur cable is still slack during this entire process. If it get's tight while you are adjusting the limit screw, you are not at the mechanical limit (metal/metal).

8- Ok, it's now going all the way down, and it's running smooth! The cable is still slack, so that means that we have a true mechanical stop. Almost done!

9- Tighten barrel adjuster to the point where it just goes taught.

10- Rotate the cranks, and go through all the gears.

NOTE- During this process, you might have to loosen the cable clamp to allow slack, as the barrel adjuster might be "bottomed" out. If it is, DO NOT leave it in this position (bottomed out) before you re-tighten the cable clamp. Back it out around one full turn, as this gives you some breathing room for fine tweaks to the system.

Last edited by Erzulis Boat; 08-21-20 at 08:14 AM.
Erzulis Boat is offline  
Old 08-21-20, 08:07 AM
  #13  
billridesbikes
Senior Member
 
Join Date: Nov 2019
Posts: 393
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 154 Post(s)
Liked 225 Times in 138 Posts
Look, if the shifting was mostly fine and you tweaked the cable tension and now it’s not fine, the problem is the cable tension. Use a work stand and loosen the cable tension (clockwise on the barrel adjuster) until it goes into the smallest cog and then indexing the shifter tighten the cable until it shifts from cog 1 to cog number 2, continue through all the cogs. Repeat from the largest cog to the smaller cog making counter-clockwise adjustments on the barrel shifter.

If the index shifting still won’t work right go through this check list:
1) The derailleur hanger is bent
2) The chain is too long/short
3) cables are worn/ or have a kink
4) The sprockets and/or chain are worn out
5) cable incorrectly clamped to rear derailleur

Finally, if none of that works buy the latest Dura-Ace Di2 group set and enjoy adjustment free shifting.
billridesbikes is offline  
Old 08-21-20, 08:07 AM
  #14  
the sci guy 
bill nyecycles
Thread Starter
 
the sci guy's Avatar
 
Join Date: Mar 2013
Location: Houston TX
Posts: 3,014
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 636 Post(s)
Liked 163 Times in 88 Posts
Originally Posted by dsaul View Post
It sounds like you turned the barrel adjuster far enough out to skip one whole cog, so you can shift all the way up until it hits the limit but you run out of clicks going down the cassette.
actually i don't run out of clicks coming down, as i said above i can still move the shifter paddle all the way to the left, but nothing happens, so it just stays on the 2nd from last small cog.
__________________
Twitter@theSurlyBiker
Instagram@theSurlyBiker
the sci guy is offline  
Old 08-21-20, 08:18 AM
  #15  
Iride01
Hits [ENTER] b4 thinking
 
Iride01's Avatar
 
Join Date: Jul 2017
Location: Mississippi
Posts: 5,679

Bikes: '20 Tarmac Disc Comp '91 Schwinn Paramount '78 Raleigh Competition GS

Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 2199 Post(s)
Liked 938 Times in 703 Posts
Is everything GRX?

GRX is intended for bikes built to handle wider tires and the chainline is moved out further. So if you are adding GRX into something that wasn't before, there might be something off in that aspect. Though it would seem most would favor you getting into the small rear cogs.

But otherwise, any time I hear about not being able to get to the small cogs I suspect cable frayed in STI or elsewhere as that has happened to the bikes I work on 3 times in the last 3 or so years.
Iride01 is online now  
Old 08-21-20, 08:28 AM
  #16  
Erzulis Boat
3rd Grade Dropout
 
Erzulis Boat's Avatar
 
Join Date: Oct 2005
Location: Santa Barbara Calif.
Posts: 1,271
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 149 Post(s)
Liked 77 Times in 37 Posts
Originally Posted by the sci guy View Post
actually i don't run out of clicks coming down, as i said above i can still move the shifter paddle all the way to the left, but nothing happens, so it just stays on the 2nd from last small cog.
If everything in your system checks out, I posted the fix above.
Erzulis Boat is offline  
Old 08-21-20, 08:57 AM
  #17  
the sci guy 
bill nyecycles
Thread Starter
 
the sci guy's Avatar
 
Join Date: Mar 2013
Location: Houston TX
Posts: 3,014
Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 636 Post(s)
Liked 163 Times in 88 Posts
Originally Posted by Iride01 View Post
Is everything GRX?

GRX is intended for bikes built to handle wider tires and the chainline is moved out further. So if you are adding GRX into something that wasn't before, there might be something off in that aspect. Though it would seem most would favor you getting into the small rear cogs.

But otherwise, any time I hear about not being able to get to the small cogs I suspect cable frayed in STI or elsewhere as that has happened to the bikes I work on 3 times in the last 3 or so years.
Yes everything is GRX. Like I said above it's brand new out of the box bike - like it literally showed up at my house in the box and I put it together.

Originally Posted by Erzulis Boat View Post
If everything in your system checks out, I posted the fix above.
I read through that but the issue is that i can't run it down until it doesn't click anymore - i wrote in my post above that the paddle still moves the full pull but nothing happens. like it knows it has 1 more shift, but can't get it to do it. so i can't get past your step 1.
__________________
Twitter@theSurlyBiker
Instagram@theSurlyBiker
the sci guy is offline  
Old 08-21-20, 09:04 AM
  #18  
Erzulis Boat
3rd Grade Dropout
 
Erzulis Boat's Avatar
 
Join Date: Oct 2005
Location: Santa Barbara Calif.
Posts: 1,271
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 149 Post(s)
Liked 77 Times in 37 Posts
Originally Posted by the sci guy View Post
Yes everything is GRX. Like I said above it's brand new out of the box bike - like it literally showed up at my house in the box and I put it together.


I read through that but the issue is that i can't run it down until it doesn't click anymore - i wrote in my post above that the paddle still moves the full pull but nothing happens. like it knows it has 1 more shift, but can't get it to do it. so i can't get past your step 1.
Then go to step 2 and loosen barrel adjuster to full slack. If it doesn't go slack, then loosen the cable clamp fastener.
Erzulis Boat is offline  
Old 08-21-20, 09:09 AM
  #19  
Erzulis Boat
3rd Grade Dropout
 
Erzulis Boat's Avatar
 
Join Date: Oct 2005
Location: Santa Barbara Calif.
Posts: 1,271
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 149 Post(s)
Liked 77 Times in 37 Posts
That is why I have step 3!
Erzulis Boat is offline  
Old 08-21-20, 09:19 AM
  #20  
Iride01
Hits [ENTER] b4 thinking
 
Iride01's Avatar
 
Join Date: Jul 2017
Location: Mississippi
Posts: 5,679

Bikes: '20 Tarmac Disc Comp '91 Schwinn Paramount '78 Raleigh Competition GS

Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 2199 Post(s)
Liked 938 Times in 703 Posts
Is there a bare cable you can hold onto while shifting down? I'll hold the cable running along the downtube between my fingers while shifting down when trying to find such things. If it you get more slack when you get to the problem cogs, then you know there is something up on the DR side with it not being able to get there. Still maybe a housing kink or badly shaped housing at the cut on the housing between your fingers and DR.

If you don't get any slack, then maybe your cable put up too short in the holdfast.


I've been ignoring the chain skips and sounds clicky parts of you comments as that might just be the result of the need for the things mentioned above. But maybe that needs to be explored more.

Last edited by Iride01; 08-21-20 at 09:25 AM.
Iride01 is online now  
Old 08-21-20, 09:30 AM
  #21  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 23,597

Bikes: Some silver ones, a red one, an orange one and a few titanium ones

Mentioned: 119 Post(s)
Tagged: 1 Thread(s)
Quoted: 3901 Post(s)
Liked 1,335 Times in 823 Posts
Originally Posted by the sci guy View Post
I didnít want to go all-in and take the chain off and start from scratch since this is a new out of the box bike and I was hoping it would pretty close to all set to ride.

I futzed with it a little more tonight and I got it to shift smoothly up and down the cassette but it still wonít go to the last cog. The shifter paddle pushes all the way but nothing happens. The chain appears to run smoothly through every other gear. The hanger is not bent as far as I can tell.

Iíll check again tomorrow but if I twist the barrel so it skips to the last cog, then adjust it each time moving back up the cassette, will that help?

First, eyeball the rear hanger to see if it is straight. It probably is but check just in case.

At this point, DO NOT GRAB A SCREW DRIVER!!!! Plug up your ears, oh Ulysses, and ignore the Sirenís song. Death on the rocks only awaits you if you grab that screwdriver!

I doubt this is your problem, however. Itís probably cable tension because shifting problems are almost always cable problems. In your case, I suspect that your cable is too tight. Shift to the high gear (lowest cable tension). The cable should be taut but not tight. If you pluck it with your finger it should vibrate but it shouldnít be like a guitar spring. If the cable is tight, back off tension some and watch what happens with the jockey wheel below the cassette.

It should move outboard (if the cable is too tight). If the cable goes slack (and if the alignment is right) and the jockey wheel doesnít move outboard, now you can grab that screwdriver that I know you want to hold, caress, and use (What is it about screwdrivers and bicycles that make people what to use one for ďfixingĒ a bike?) Turn the high limit screw enough to move the derailer so that the jockey wheels are aligned below the cog.

Once you got the limit screw adjusted, grind the damn thing off so that you arenít tempted to grab that irresistible screwdriver again! (Kidding but only slightly)
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is offline  
Old 08-21-20, 12:48 PM
  #22  
dsaul
Senior Member
 
Join Date: Jan 2013
Location: South Jersey
Posts: 1,843
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 559 Post(s)
Liked 363 Times in 261 Posts
Originally Posted by the sci guy View Post
actually i don't run out of clicks coming down, as i said above i can still move the shifter paddle all the way to the left, but nothing happens, so it just stays on the 2nd from last small cog.
It's been a while since I had a Shimano shifter, but I think the shifter paddle will still move after it runs out of clicks. If it doesn't click, you are in the lowest gear position on the shifter.
dsaul is offline  
Old 08-21-20, 01:14 PM
  #23  
Iride01
Hits [ENTER] b4 thinking
 
Iride01's Avatar
 
Join Date: Jul 2017
Location: Mississippi
Posts: 5,679

Bikes: '20 Tarmac Disc Comp '91 Schwinn Paramount '78 Raleigh Competition GS

Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 2199 Post(s)
Liked 938 Times in 703 Posts
Originally Posted by dsaul View Post
It's been a while since I had a Shimano shifter, but I think the shifter paddle will still move after it runs out of clicks. If it doesn't click, you are in the lowest gear position on the shifter.
Yes, you are correct about that. At least with what I've experienced.

Also a good reason to hold on to the bare cable as you click the paddles to know how the cable reacts to each click. Sometimes even after having reached it's limit it might feel like it's giving a click still.
Iride01 is online now  

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 My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.