How to Diagnose and Fix a Squeaky Chain

A squeaky chain is a common problem for bike owners, but fortunately, it's usually an easy fix. Here's how to diagnose and fix a squeaky chain:

Diagnosis:

1. Check for dirt and debris: Dirt, grime, and debris can accumulate on the chain and cause it to squeak. Use a degreaser and a brush to clean the chain and see if the squeaking stops.

2. Check for worn or damaged chain: Over time, chains can stretch and wear down, causing them to squeak. Check the chain for signs of wear, such as rust, corrosion, or elongation. If the chain is worn, it will need to be replaced.

3. Check for misaligned chain or gears: A misaligned chain or gears can cause the chain to rub against the derailleur or other components, resulting in a squeaking sound. Check the chain and gears to make sure they are properly aligned.

4. Check for loose bolts: Loose bolts on the chainring, derailleur, or other components can cause the chain to rattle or vibrate, resulting in a squeaking sound. Check all the bolts on your bike and tighten them as needed.

Fix:

1. Clean and lubricate the chain: If the chain is dirty or dry, clean it with a degreaser and lubricate it with a chain lubricant. Apply the lubricant to each link of the chain and wipe off any excess.

2. Replace the chain: If the chain is worn or damaged, it will need to be replaced. Chains are relatively inexpensive and can be easily replaced by a professional bicycle mechanic.

3. Adjust chain and gears: If the chain or gears are misaligned, they will need to be adjusted. This can be done by a professional bicycle mechanic or by following a step-by-step guide or video tutorial.

4. Tighten bolts: If loose bolts are causing the squeaking sound, tighten them with a wrench or allen key. Be careful not to overtighten, as this can damage the threads or components.

In summary, a squeaky chain can be caused by several factors, including dirt and debris, worn or damaged chain, misaligned chain or gears, or loose bolts. By diagnosing the cause of the squeaking and addressing it with proper maintenance or repairs, you can keep your bike running smoothly and quietly.

How to Fix a Slipping Chain and Gears

Tools You Will Need

Bike stand
Chain tool
Small screwdriver

One of the most important things to maintain on your bicycle is the drivetrain. This includes the shifters, chain, front and rear derailleur, the cassette and crankset. They all work together. Several of these parts can be responsible for slipping gears, making it important to perform regular maintenance of you bicycle. A well maintained bicycle increases the safety and enjoyment of your ride and decreases the chances of getting a gear stuck, jammed, or the chain slipping right off the gear cassette.

How to Fix a Slipping Chain and Gears

Step 1

Place your bike in a bicycle stand. This will allow you to clearly access all the parts and spin the pedals to see how the drivetrain is performing. If you do not have a bicycle stand, put the bicycle upside down and rest it on the seat and handlebars.

Step 2

Look over the chain for excess wear or bent links. Using a chain tool, slip each of its ends through the links of your chain and check your chain against its wear indicators. If the chain is worn out, replace it. Don't bother trying to fit it, once a chain is worn out it is no longer good for using on a bicycle. If a link is bent, either replace the link or the entire chain.

Step 3

Check your gear sprockets. The sprockets are under pressure from the chain, especially when climbing. If any of the edges are no longer rounded at the ends and instead resemble a shark's tooth, it's time to replace the cassette because it's probably causing your chain to slip.

Step 4

Examine your rear derailleur. If the chain and sprockets are fine, chances are this ghost shifting is caused by either a bent derailleur hanger or the derailleur is out of alignment physically. This is common, especially as new cable stretches, often causing the derailleur to shift incorrectly.

Step 5

Inspect the derailleur hanger from the rear. The pulleys should line up. If they appear out of alignment, the derailleur hanger is likely to blame for your poor shifting. This is a cheap and easy part to replace, but change it as soon as possible to decrease the chances of it breaking off or flying into your spokes.

Step 6

Adjust the limit screws on the derailleur with a screwdriver. If the hanger looks straight, adjusting the screws is the next logical diagnostic tool. There is a high- and low-limit screw on the derailleur as well as a tension-adjustment screw. These are marked by an "L," a "B" and an "H." These screws set the parameters on where the derailer can move.

Step 7

Adjust the B screw until the pulley is rubbing against the largest sprocket. When it is adjusted to just clear the chain, tighten the screw.

Step 8

Turn to the H-limit screw. First, relieve any pressure on the cable by loosening the cable adjuster. Examine how the chain is riding on the smallest sprocket. If it's rubbing on the next gear, loosen it until it's centered. If it appears to be moving toward the axle, tighten the screw. Readjust the cable tension and see if this solves the problem.

Step 9

Shift down to your lowest gear and check the L-limit screw if you are still experiencing problems. If the chain is pulling toward the axle as it rides on the sprocket, tighten the screw clockwise until it is lined up underneath. If the opposite is happening and the chain is pulling down, loosen the screw. Before riding, run through all the gears to ensure the derailleur will not shift into the axle.

Tada! You're done!

Keep on riding!

12 Step Derailleur Tuning

Want to learn how to adjust and fix your derailleurs? Here is the 12 step program as set forth by Jerzy "Smokey" Dymny of the Quadra Bike School.

1. Rear derailleur. Shift to high gear (small ring) and disconnect DR cable. (If DR has a reverse-rise spring the DR travels in opposite direction when released. In that case reverse these instructions for high and low cogs.)

2. Set high limit screw. Chain must travel smoothly on smallest cog but not go past it.

3. Check the complete cable path and reconnect rear derailleur cable.

4. To tune rear shifting, shift chain to middle chainring in front & tighten rear barrel adjuster until each shift click produces one clean downshift in the rear.

5. Adjust the low limit screw to let the chain reach large (low) cog but not shift past it. Check guide pulley spacing and adjust “B” screw to increase spacing if necessary.

6. Test up shifts. Turn barrel adjuster slightly in, if any shift is slow. Repeat till perfect.

7. Leave rear DR in low (large). Disconnect front cable. Adjust height of front derailleur 1–3mm above large ring.  Set front DR low limit screw. Tightening low limit screw pushes derailleur outward from frame.

8. Check complete cable path. Reconnect front cable.  Leave front DR in small ring. Test rear DR shifts up to second highest cog.

9. Shift front DR to middle ring. Test rear DR shifts through all gears.

10. Place Chain/String tool on smallest rear cog and largest chainring. Rotate front cage to match the cage engagement gap to the string angle.

11. Shift to the large ring. Set high limit screw. Test rear shifting to second lowest cog.

12. Check that front derailleur shifts through whole range & downshifts quickly.

© 2012, Quadra Bike School

How To Fix Your Derailleurs

Please help me I'm so stressed over this. I just bought a new Supercycle bike from Canadian Tire. They did not adjust the derailleurs at the store so I decided to try it but I wound up loosen the cable too much and it came out of the derailleur all together. I am planning a cycling trip to Toronto on the weekend and I don't want to rent a BIXI bike for the entire weekend because that would cost a small fortune. Is there anyway I can fix this myself in a hurry? PLEASE HELP ME. - Andrew in Whitby, Ontario

Not to worry Andrew, help is available but it won't be easy. Derailleurs are basically the most complicated things to fix on a modern bicycle.

#1. First check to see if you have a bent derailleur tab. (You probably don't because your bike is brand new, but lets follow procedure here in case other people have problems.) If it is please see this other post on "Fixing a Bent Derailleur Tab".

#2. Get yourself a copy of Barnett's Manual (the books aren't cheap so a PDF will suffice) and read chapters 33 and 34.

I cannot possibly fully explain all the intricacies of fixing derailleurs in one blog post. Barnett takes TWO chapters to do it, one for front derailleurs and another for rear derailleurs. If you view the PDF it is pages 591 to 649.

Failing that check out this website: sheldonbrown.com/derailer-adjustment.html which is reasonably helpful, but has really shoddy graphics and skips over a lot of parts (It should be sufficient to help fix Andrew's problem however). That site does however get the point across that derailleurs are basically the most complicated things to fix on a modern bicycle.

Maybe someday I will do a detailed post on how to fix derailleurs, but if I am anything like Barnett such a post would take me a week to write and be 50+ pages long.

Good luck Andrew!

Fixing a Bent Derailleur Tab

Got a bent derailleur? Its probably a Shimano, the most popular derailleur sold on the market.

Well you're in luck, they're usually pretty easy to fix... Usually its not the derailleur that is bent anyway, but the tab (also called a hanger) the derailleur attaches to the frame has become bent. (Its actually a very COMMON problem for bicycle mechanics.)

The derailleur itself is usually made from a very strong metal and the parallelogram design makes it highly unlikely to get damaged. The weakest point therefore is the tab and if the derailleur gets bashed hard the tab will usually bend inwards. If it gets bent really far your derailleur will end up rubbing or jutting into your rear wheel spokes. Even a minor bash to your derailleur can muck up your alignment if the tab is weak.

You can roughly check the alignment with your eyes, if you look at the derailer from the rear. The derailleur pulleys should be lined up vertically with no sideways slant.

Is the tab Steel or Alloy?

If the tab is steel it can be easily bent back into position and realigned.

If its alloy metal you may be able to bend it back into position, but the next time it gets damaged it will be even worse. If it gets damaged again and again eventually the tab will snap right off. (A bit like twisting the tab off a pop can.)

To do a really good job of fixing the tab you will need the proper tool. Bicycle mechanics usually have this special tool in their shops so its not something a person would normally have in their garage.

Because many new bicycles now have narrow chains, Hyperglide, 7-9 speed cog sets proper derailleur alignment becomes really important to shift normally and smoothly. You want the derailleur to be PERFECTLY aligned to the front gears and the chain.

So what you want is a Park Derailleur Hanger Alignment Gauge, which costs about $60 US to buy unfortunately... without it you will just have to make do with whatever tools you have.

STEP ONE: Place the chain on the smallest gear.

STEP TWO: Remove the derailleur from the derailleur tab, with a 5mm allen wrench.

STEP THREE: Remove the derailleur and chain.

STEP FOUR: Use a Park Derailleur Hanger Alignment Gauge to realign the derailleur tab. (The tool uses the rear wheel as a guide so make sure your rear wheel is on perfectly straight!) If you don't have that tool you will have to bend the tab using whatever tools you have available. If its an alloy tab try to be gentle with it.

DO NOT JUST YANK ON IT. You don't want to overcompensate and bend the wrong part by accident or break it off entirely.

STEP FIVE: Reinstall the chain and derailleur.

STEP: SIX: Check and modify your derailleur and derailleur screws to make sure your derailleur is functioning perfectly.