Drivetrain Overhaul:

Your guide to maintaining your drivetrain.

So let’s take a look at what you can do at home to keep your bike’s drivetrain in tip-top shape, including basic maintenance of your crankset, bottom bracket, chain and derailleurs.

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Crankset and Bottom Bracket Overhaul:

In order for your bike to move forward, your physical effort (aka: pedaling) is transmitted to the bike directly thru the cranks which in turn, propels the bicycle. The crankset is a major part of the bicycle’s total drivetrain. With proper care, your cranks and bottom bracket will last a very long time. In this section we will focus on maintaining your crankset and bottom bracket (we’ll refer to it occasionally as a “bb” throughout this section), including inspection, tools needed, removal and installation.

Please be advised: We are primarily focusing on standard square-tapered and splined (Hollowtech or ISIS) style setups as these are the more common setups that you will encounter. We will cover one-piece and other styles of cranksets/bb in the near future.

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Crankset and Bottom Bracket Anatomy:

The crankset is composed of the following basic parts:

- Crank arms

- Chainring

- Chainring bolts

- Crank bolts

Now we will look at the bottom bracket, but before we go into the anatomy, let’s go over the differences between a “sealed” bb and one that is not:

Most (if not all) modern bb’s are generally a “sealed” unit (see photo below), meaning that it is a self-contained mechanism.

Older bottom brackets are not self-contained and can be taken apart for maintenance (compare bb's in photo below). However some of them have a plastic sleeve that protects them from the elements. These bb’s were referred to as “sealed” as well but should not be confused with the bb’s shown above.

Regardless of the style, all bb’s share the following common parts:

- Spindle

- Bearing cups

- Cartridge bearings or loose bearings (either ball or pin bearings)

- Bearing cup lockring

For more information on the different styles of bottom brackets, check out the “Drivetrain” section in Bike Anatomy.

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Signs you need a crank/bb overhaul:

Here are a few signs to signal that you need to perform a crankset/bb overhaul:

- Sluggish or tight pedaling.

- Grinding noise when pedaling.

- Crankset/bb feels loose or wiggles.

- You’ve ridden your bike through deep water (mountain bike, of course).

- You see visible damage to the crankset/bb.

- Your bike has been sitting out, exposed to the elements for a significant amount of time (6 months to a year).

- Anytime your bike has been involved in a major crash. You’ll not only check your crankset, but all your major components as well as the frame and fork.

- You’ve been riding for a year and your bike feels fine. Huh? No it’s not a mistake. A crankset/bb overhaul should be performed every year as part of your normal bike maintenance. Very important in the overall drivetrain overhaul scheme of things. ______________________________________________________________________________

Tools Needed:

For general crankset and bb maintenance or a major drivetrain overhaul, you’ll need the following tools:

- Crank Extractor: This tool is used to remove the cranks arms from the bottom bracket. Get the specific tool for the particular style of crank/bb combination that you have. Example: The crank extractor for a square tapered crank will not remove a crank with a splined setup.

- Adjustable wrench/socket wrench/large allen wrench: Depending on a the style of the crank extractor, you will need one of these style of tools to turn the extractor. The allen wrench/socket wrench is also used to remove the crank bolts (if appropriate for your bike).

- Large screwdriver (not shown): For removing dust caps on older cranksets.

- BB bearing cup removal tool: This tool is used to remove the bearing cups and body assembly of a bb from the frame’s bb shell.

- Spray lubricant/degreaser/cleaner: You need this for hard to remove parts and to clean you bb’s bearings, spindle and bearing cups (if overhauling an older style bb).

- Multi-purpose grease: For re-lubrication of bearing parts and threading on frame’s bb shell prior to installation of bb.

- Workstand: For holding your bike while you work on it. Highly recommend to make your job easier.

- Rags: To wipe-up/clean-up grease and grime from parts and bike frame.

- Drop cloth: To catch loose bearings and any other small parts, plus keeps your work area clean. ______________________________________________________________________________

Removing the crank arms:

When performing a drivetrain overhaul, the first thing you must do is to secure your bike on a bicycle repair stand (if you have one) and place your drop cloth under your bike. If you don’t have a work stand, lean your against a wall or other solid surface, but make sure you have a good handle of your bike while working on it or you could damage it or even hurt yourself.

Remove crank bolts/dust caps from crank arms using the appropriate tool for your style of crank.

Slowly thread crank extractor tool onto crank arm. Use care when threading the tool in since you risk damaging the threads on your tool and/or your crank arm if you rush it. Once it is seated in the crank arm, use your adjustable wrench to tighten down the extractor tool.

Hand-tighten the extractor portion of the tool until it stops. Attach your wrench to the extractor.

Grasp one crank arm with your left hand and the wrench with your right hand. Slowly turn the wrench clockwise while counteracting with the crank arm. You will feel the crank arm slowly move out.

Once the crank arm is off, take the chain off the chainring and your crank is now removed. Repeat on the opposite crank arm if removing entire unit. You now have access to the bb.

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Removing the Bottom Bracket:

Insert and properly seat your bearing cup removal tool into the bb (non-drive side first).

Insert wrench into the removal tool. Grasp the bicycle frame with one hand and with your other hand, turn the wrench CLOCKWISE to remove the bb lock cap.

Repeat on opposite side (drive train side) but this time you will turn the wrench COUNTER-CLOCKWISE.

Older style bb’s have a separate lockring that requires the use of a lockring tool.

Once you have removed the bb assembly, place it aside.

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Cleaning the frame’s BB shell:

First, start off by spraying the bb shell with a degreaser/cleaner. Spray liberally and allow to sit for a few minutes or longer, depending on how dirty it is.

Use an old cloth/rag to wipe it dry.

If you have a plastic bristle brush, scrub the threads of the bb shell to remove any old grease or dirt that is caked into the threads. A toothbrush will also work.

Use a screwdriver or an ice pick to clean hard-to-remove dirt/grease on the threads.

Run your fingers lightly over the surface of the bb shell treads to check for irregularities and to locate any potential damage to the threading.

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Cleaning the BB:

For sealed mechanisms: Place the bb in to an old plastic container. Spray the entire outer portion of the bb assembly and allow to sit for a minute or longer. Wipe dry.

Check spindle by turning it to feel for any roughness or resistance. If BB feels notchy or rough, that would be a good indicator that it is time to replace it.

For bb’s that are not sealed: Spray bearing cups, lockrings, spindle and bearings with a degreaser and allow to sit for a few minutes. Wipe all components dry.

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Reassembly of the BB:

On older BB’s, apply a layer of grease inside the bearing cups prior to reinserting ball bearings.

Apply grease on threading of bb assembly/bearing cups.

Apply grease on entire interior of bb shell on the bike frame, not just on the threads. This will aid in waterproofing the bike frame and is especially beneficial for steel frames.

Installation of bb is the reverse of the removal instructions listed above.

Once installed, apply a thin layer of grease on spindle surfaces that make contact with the crank arms.

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Cleaning the crankset:

Before you reinstall your crankset, it would be wise to clean them as well to aid in better shifting performance.

Spray a degreaser/cleaner on the chainrings and allow to sit for a few minutes. If your time permits, removing the chainrings from the crank arm would aid in more thorough cleaning.

Use a stiff bristled brush to scrub the chainrings. Then wipe dry.

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Clean your front derailleur now:

And while we’re at it, you might as well clean your front derailleur and the surrounding area while you have the crank off. Use your degreaser and brush to remove any caked on dirt and grease.

Spray lubricant to moving parts and wipe any access fluid off to prevent attracting dirt. Check shifter cables for rust and worn strands.

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Reinstalling the crankset:

Reattach chain to chainrings and insert crank onto spindle of bb. (As shown above) Reinsert other crank arm in opposite side. Make sure both cranks arms are seated on spindle properly by pushing the cranks towards the bb.

Once in place, reattach mounting bolts and tighten using appropriate wrench.

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Maintaining your chain:

Another important step in your drivetrain overhaul is the maintenance of your chain. The chain is essentially the backbone of your drivetrain. Without it your bike wouldn’t go anywhere. The chain is probably the most “stressed” item on your bike.....and sometimes the most neglected. So in this segment of your drivetrain overhaul, we will look at how to take care of this essential component of your drivetrain. We will cover both minor cleaning with your chain still attached to your bike and major cleaning with directions on how to remove/reinstall your chain.

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Signs you need to maintain your chain:

Here are a few indicators that your chain is in need of a little TLC:

- Sticky links.

- Squeaking noise from chain while pedaling.

- Links are dry (no lubricant) or rusted.

- Links appear visibly worn.....scuffed.

- Bike shifts poorly or skips even when not shifting.

- Chain breaks under load (while pedaling).

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Tools needed to maintain your chain:

For general maintenance of your chain or a major drivetrain overhaul, you’ll need the following tools:

- Chain Tool: This tool is used to split and reattach the chain. It accomplishes this by pushing the chain pins away or towards a link. Newer chains usually come equipped with a special link that comes undone without the need for a chain tool. But a chain tool comes in handy for these types of chains as well if the chain needs to be shortened for whatever reason.

- Chain Hanger Tool: This tool is used to hold a chain together when it is being split or reattached. Like having a third hand.

- Plastic bristled brush: For cleaning hard-to-reach areas of a chain. A toothbrush can also be substituted for this.

- Steel brush: Use this if your chain has surface rust.

- Chain cleaner tool/chain cleaning fluid (Optional): This is a self contained cleaning device that is much more thorough then a standard brush, but costs more as well. But it is well worth it since it makes cleaning your chain not as messy and faster, without having to remove the chain from the bike. Some chain cleaning fluid also contain a lubricant, so you clean and lubricate your chain in one step.

- Spray lubricant/degreaser/cleaner: You need this for hard to remove parts and to clean your chains links if you don’t have a chain cleaner tool

- Old container: For soaking your chain to break apart old grease and grime.

- Workstand: For holding your bike while you work on it. Highly recommend to make your job easier.

- Rags: To wipe-up/clean-up grease and grime from chain and bike frame.

- Drop cloth: To catch small parts, plus keeps your work area clean.

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Minor cleaning of your chain:

For minor cleaning jobs that don’t require a major drivetrain overhaul, you can clean your chain right on the bike using a chain cleaner tool as shown above or using a degreaser spray, your brush and a rag as shown below.

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Removing your chain for a major cleaning:

Attach your chain hanger to one link of your chain and pull down a section of chain. Attach other end of chain hanger to another link as shown in photo above. Position your chain tool as shown, if you have a chain equipped with a removal link, you can skip this step and just undo your chain.

With the chain tool in position, aim the tool’s pin extractor to the chain’s pin and slowly turn the “t-handle” of your chain. As you turn the handle, the pin extractor pushes the chain pin off the chain. BE CAREFUL! Make sure you don’t turn the handle so much that you end up pushing the chain pin completely off the chain. If you do that, it will be extremely difficult to reinstall. Push the chain pin out just enough so that the links can be separated.

Once you have split the chain, you can thread it off the drivetrain for cleaning.

Place your chain in a container and pour your chain cleaning fluid directly on to it . Allow to soak for a few minutes. Scrub chain while in the fluid. Remove chain from fluid and dry off with a cloth.

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Clean your rear derailleur now:

Part of the drivetrain overhaul is proper maintenance of your derailleur. So while you have your chain off, take the time to clean your rear derailleur and the surrounding area (including the frame’s chainstay and dropouts) by using a spray degreaser and a rag.

Use the tip of a standard screwdriver and scrape off any caked on grease and grime on the pulleys and any other parts of the derailleur.

Spray some lubricant to all moving parts and wipe off access.

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Reinstalling your chain:

Thread your chain thru the derailleurs, cassette and cranks. Attach your chain hanger tool to both ends of your chain as shown in the photo above.

Join the links together and position your chain tool’s extracting pin so that it will push the chain pin back into the links, which in turn, reattaches the chain. Make sure that the links are aligned so that the chain pin goes in smoothly and straight.

Once the chain pin is in place, you will notice that the links appear to be stiff. This is completely normal. To remedy this, twist the stiff links side to side and move back and forth so that it will loosen.

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By periodically conducting a drivetrain overhaul on your bicycle, you will ensure many happy miles of worry free riding.

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