From the Workbench: General Drivetrain Maintenance 3
Few parts on your bike require more attention than your drivetrain. The drivetrain is exposed to the elements as well as the stresses your legs put on it as you motor up and down the trails. While bike maintenance may seem a daunting task to some, we're here to show you that working on your bike to keep it running smoothly is something we can all do.
General drivetrain maintenance involves equipment checks, repairs and routine preventative tasks. We guide you through the processes while showing you the proper tools needed to ensure your bike runs smoothly and shifts on command.
- Chain Tool
- Chain Wear Indicator
- Diagonal Pliers
- Link Pliers
- Hex Keys
- Torx Keys
- Cable Cutter
- Crosshead Screwdriver (Shimano derailleur only)
- Shock Pump
- Multi-Purpose Lube
- Shifter cable(s)
- Shifter cable housing
- 4mm ferrules - Our bike uses four ferrules due to the non-continuous housing. Your setup may vary.
- Cable tip(s)
How-To Check Your Chain If Your Chain Is Worn
First, check your chain for excessive wear. This is one of the easiest and most important steps to maintaining a properly running drivetrain. Failing to regularly check your chain for wear can result in a chain that slips under load and accelerated wear to both the cassette and front chainring(s).
Lower the chain wear indicator onto your chain.
Let the chain wear indicator tip slide between the links and note at which point it stops. If it slides all the way to the .75 indicator, it's time for a new chain. If it slides all the way to the 1.0 indicator and the tool lays flat on your chain, there is the possibility your cassette is worn out as well and will no longer work properly with a new chain.
- If you decide to only replace the chain when the chain wear tool indicates 1.0, take caution when first putting load on the drivetrain. If the cassette is worn, it may slip under power, possibly resulting in injury.
It's good habit to do this simple check after your post-ride chain cleaning and lube as it takes only a few seconds. We're assuming you already know how to clean and lube your chain. If not, follow this quick tutorial on general bike lubrication.
How-To Replace Your Chain
If your chain was worn to at least .75 like ours was, it's time for a new chain. Depending on your specific drivetrain, there are a few different ways to make the replacement. Since we're using a SRAM 1x11 drivetrain, we'll be using SRAM's method on chain installation and measuring. Please refer to your specific manufacturer's directions when doing this job.
- If this is your first chain install, now is a good time to pull out your cell phone and snap a quick photo or two of how your chain is routed around your cassette and through your derailleur for future reference.
Step One - Checking Chain Length
Attach a shock pump to your rear shock and note the pressure you're running. Keep in mind you can lose up to 10PSI by just attaching the shock pump, so use this number only as a guideline and be sure to measure your sag when you inflate the shock after the chain replacement.
Once you've noted your shock's pressure, deflate the shock completely. This is necessary in order to cycle the suspension after the new chain is installed, ensuring your chain is long enough throughout the bike's travel and to measure the new chain while the bike's wheelbase is at its longest.
Shift the chain into the biggest gear on the cassette. If you're running a 2x or 3x drivetrain, shift the front derailleur so that the chain is on the biggest ring up front. Place the bike on the ground and cycle the rear suspension to see if your chain is at an acceptable length. If the drivetrain is put under obvious stress as you cycle the suspension, your chain is too short.
Put the bike back in the stand and shift both front and rear to the smallest ring and cog to verify the rear derailleur maintains tension on the chain. If there is too much chain slack in this gear configuration, your chain is too long.
If the old chain passes these two tests then it is the correct length and you can use it as a guide to measure your new chain, saving time in Step Three below.
Step Two - Removing Old Chain
There are two tools you may use here; a normal chain tool or the chain link removal tool (SRAM only). Since our chain is a SRAM chain, we're using the link removal tool. As mentioned above, if you're new to the this process, make sure you're aware of how the chain routes through the system.
Locate the the SRAM Powerlink and use the link removal tool to unsnap it. Remove the tool and links and you can now remove the chain from your bike.
Step Three - Measuring New Chain Length
If you can not use your old chain as a guide for chain length, it may be necessary to have someone help you with this step as you'll need to compress the bike's rear suspension while measuring the chain simultaneously. It should be noted that these are directions specified by SRAM for chain installation, but we usually skip the compressing-the-rear-shock portion of measuring a new chain. However, since we're doing this by the book, we recommend you do the same.
Have your buddy compress the rear shock while the bike is out of the stand. While the rear end is compressed, run your new chain around the biggest gear on the cassette and the biggest ring up front. There is no need to run the chain through the rear derailleur at this point. Grab both ends of the chain and bring them together. Mark the link at which one of the ends overlaps the other while the chain is reasonably taut.
- Note: With a SRAM chain and its use of a Powerlink, you'll be cutting the chain so that the male portion of the link will now be the end. Since Shimano chains use a chain pin, you'll be marking the chain so that the female portion of the link is on one end of the chain and the male portion is on the other. Refer to the diagram below for reference.
Step Four - Cutting New Chain
Now that you've marked the link where your chain becomes taut, count the appropriate additional links to determine where you'll make your break. Via SRAM's instructions, we need an additional two links to our chain from the mark we made.
- Note the "x" is only the mark you made where your chain is taut, not where you'll be breaking the chain. The actual break will be made by using the "x" to count out the additional links required to account for chain-growth. For our SRAM chain, we left two additional links as pictured above.
Now that we know where to make the cut, place the chain in the chain tool making sure the pin in the chain lines up with the pin in the chain tool. Once lined up, turn the chain tool's pin handle clockwise to drive the chain pin completely out.
Step Five - Installing the New Chain
Chain installation. Our SRAM 1x11 rear derailleur cage can be locked-out making chain installation easier. Extend the cage by hand and push the button with a picture of a pad-lock on it.
Run your chain through your rear derailleur, around your cassette and over your front chain ring. If you're unsure of how to route the chain through the derailleur, hopefully you took a cell phone picture like we mentioned earlier. If not, use the picture below for reference. For this step it's easiest to have the chain run on the top of your side of your drivetrain so both ends can dangle.
- Note: Narrow//wide users, it's important to make sure you line-up the wide portion of the link with the wide teeth on both your front chainring and rear derailleur pulleys.
- Note: Shimano users, chains are directional and you always want the male end of your chain (the small link) to be pulling the female link. Refer to Diagram 1 in Step Three above.
Once you've properly routed the chain, bring both ends together and install either the Powerlink (SRAM) or the chain pin (Shimano). Note that Powerlink for 11-speed are directional, indicated by an arrow on the link. When installing the Shimano chain pin, you will feel a distinct click once the pin has been fully pressed-in. To remove the excess part of the pin, we usually just use the flip-side of our chain tool to snap it off. You can use needle-nose pliers as well. For SRAM users, to make sure the Powerlink has fully seated, rotate your crank so the Powerlink is on-top and between your cassette and front chainring. While holding your rear wheel or rear brake, give your drive-side crank a little thump with your hand in the same direction you pedal and it should snap in place.
Step Six - Checking Chain Length
Shift into the biggest ring both up front and on your cassette, place the bike on the ground and compress your rear suspension, making sure the derailleur doesn't max-out at any point in the bike's travel. Then put the bike in the smallest cog out back and smallest ring up front and check the the derailleur is still tensioning the chain. If both tests are successful, you've properly sized and installed your new chain. We'll cover how to adjust your derailleurs later on in this tutorial.
How To Replace Your Shift Cable And Housing
One of the most important elements to maintaining smooth and easy shifting is staying on-top of your cable and housing maintenance. Worn, blown-out or grimy housing adds friction to the system making your derailleur lag when shifting into higher gears and more difficult to shift into lower gears. While replacing your cables and housing may seem a bit intimidating, especially with internally routed frames, we have a few tricks to keep this repair as simple and straightforward as possible.
Set your barrel adjuster(s) completely in by turning the barrel clockwise.
Note how your cable is run through and clamped in your rear derailleur. This is a good time to take a photo for later reference as there are a number of ways the cable can be mounted and it varies from derailleur to derailleur. Our SRAM derailleur uses a T25 bolt as the cable-anchor, but it's not uncommon for this bolt to use a 5mm allen and sometimes even a 4mm. Be sure to use the proper tool specific to your derailleur.
Shift the rear derailleur into the highest (smallest) gear so the shifter cable has the least amount of tension on it. Using the proper tool, which in our case is a T25, loosen the cable anchor bolt until you can remove the cable. This is also a good time to check that your derailleur is snug to the frame by using the T25 to check the derailleur mounting bolt.
Using your pair of diagonal pliers, snip the end of your cable off to get rid of the cable tip and any frayed wires. This will make running the new housing a lot easier. You can now pull the cable completely out of the rear derailleur, but DO NOT pull the cable from any of the housing yet.
Remove any housing guides. Our bike uses small zip-ties to secure the housing to the frame, but some bikes come with frame-specific guides that can use a 2.5, 3 or 4mm allen key. Be sure to use the proper tool for the job, which in our case was the diagonal pliers.
- Note: These next couple steps are specific to internally-routed frames. If your bike uses all external cable routing, skip ahead to Step Nine.
Now that your housing is free from the housing guides, carefully slide the rear portion of housing out of the back of the chainstay, making sure to leave the cable through the stay. You will use the cable as a guide when installing the new housing. Note how our housing is damaged, if there are any areas on your housing that look like this, it's time to replace it. While our bike still shifted fine like this, the damaged area is a huge weak spot in the housing and could easily blow-out completely during a shift and ruin your ride.
Using your old housing as reference, cut the new housing to the same length with your cable cutters. It's common to deform the inner-sleeve of the new housing while making this cut which you will have to fix. Our Birzman cable cutters have a handy built-in poker, but if your cutters don't have this feature (most don't), a push pin, small nail or a sharpened spoke will do the trick. The goal is just to re-open the deformed inner-sleeve so that you can easily run the new cable through it.
Use your old cable to carefully guide the new housing through the chainstay. It's easiest to use your right hand to hold the exposed part of the cable between the stay and the downtube to keep it from pushing through while you run the new housing. Once the housing is completely through the stay, you can pull the cable completely out of the rear housing. Leave the cable through the front triangle, you will use it as a guide in the next step.
Since our frame has no internal housing in the front triangle, we removed the housing-stops where the cable enters and exits the down tube, leaving the existing cable running through. This allows us to run an old piece of housing through the downtube of the frame using the existing cable as a guide for the new cable. Once this piece of housing is through the downtube, you can pull the old cable out completely, taking care not to let the housing come out of place. For some bikes this isn't necessary as either the housing runs through the frame already or there is an internal guide already installed. If your frame has neither of these features and you can't use old housing as a guide like we did, it's a matter of manually fishing the new cable in and out of the front triangle. A bent spoke to use as a hook and a flashlight is often needed in this situation.
Step Eight - Replacing the Cable
For this step, it's easiest to remove your shifter completely. Our SRAM shifter is mounted using a T25, but it's not uncommon for the shifter to be mounted using a 5mm or 4mm allen bolt. Using the appropriate tool, remove the shifter.
Next, we're going to remove the top-plate of the shifter in order to remove the old cable and install the new one. For other shifters, this step is sometimes not necessary and the cable can be removed without opening the shifter. Check your manufacturer's directions for specifics.
Using a 3mm allen key, unscrew the bolt holding the top-plate on and completely remove it. The cable end is located under the spring on the red-plate. Making sure the shifter is still in the highest gear, carefully push the cable from the barrel adjuster side to remove it. Sometimes it is necessary to use a spoke or poker to free up the cable end, as was the case for us.
Remove the old cable and install the new one, running the cable through the red-plate and out the barrel adjuster. Re-install the top-plate and mount the shifter back to your bars with the new cable dangling.
Repeat the sizing procedure from Step Five to cut and prep the new front section of housing. We like to use a small amount of multi-purpose lube like Birzman's Chain Lube, Maxima's MPPL lube or Tri-Flow. Use the lube on the housing ends and a little inside the housing. This prevents the housing ends from rusting and helps reduce friction in general. Once you've lubed the housing, install the ferrules to both ends of the housing, making sure to completely seat them to prevent shifting issues in the future. Repeat this process for the rear portion of housing.
Using your fingers, apply a small amount of grease to the entire length of cable and slide the new section of housing with ferrules installed onto the new cable and seat the top ferrule in the shifter. It's important not to forget to put the housing stop which was removed to run the old housing on the cable at this point, too. With loose end of the cable, use the old housing you just installed to guide the cable through the downtube and out the other end. You can now remove the old housing from the front triangle.
Seat the other end of the top piece of housing into the housing-stop where the cable enters the front triangle. From here you can run the cable through the rear portion of housing you installed in Step Six and prepped in this step. Seat both ends of the housing, one end in the frame and the other in the rear derailleur. Then, using the photo you took in Step Two, route the cable through the derailleur.
While slightly pulling on the cable to create some tension, make sure the cable is properly positioned under the cable-anchoring bolt and use the proper tool, a T25 in our case, to secure the cable to the derailleur.
We like to leave at least two fingers worth of extra cable exposed after the anchor-bolt. Using your diagonal cutters or cable pliers, snip off the excess cable. Put the cable tip on and using the diagonal pliers, gently put two or three indents in the cable tip to secure it to the cable.
Now that your new cable and housing are installed, it's time to adjust the rear derailleur.
How To Adjust Your Rear Derailleur
There are two main steps to properly adjusting your rear derailleur: setting the limit screws to prevent over-shifting and putting the proper amount of cable tension on the cable to provide quick and positive shifting.
Your barrel adjuster on the shifter should already be turned all the way in from a previous step, but if not, now's the time to do it. With the highest gear selected, locate the two limit screws, usually on the back portion of the rear derailleur. Sometimes they will be marked "H" and "L," for high and low. Our SRAM derailleur doesn't indicate which is the high-limit and which is the low-limit, but by putting the chain in the highest gear we can try turning each limit-screw to see which moves the derailleur slightly. The high-limit screw will only move the derailleur with the highest gear selected while the low limit will do nothing. For reference, our high-limit is the screw on the left and the low-limit is the screw on the right, pictured above.
Using a 3mm allen key for SRAM or a crosshead screwdriver for Shimano, eyeball the top pulley and your highest gear to see if they are in-line with each other. If the pulley is on the outside of the highest gear, slowly tighten the high-limit screw to bring the pulley in. If the pulley is too far inside the highest gear, loosen the high-limit screw until it lines up.
Shift the into the lowest gear (biggest) on the cassette. Repeat the eye-balling procedure from Step One but adjust the low-limit screw. We will fine tune the limits in a later step.
Shift back down into the highest gear. While pedaling the bike slowly in the stand, shift down from the highest gear to the second-highest and pay attention to how quickly it shifts, if at all. If it's slow to shift or doesn't shift at all, there's not enough tension on the cable. Using the barrel adjuster on your shifter, back the adjuster out a half turn or so and try shifting from the highest gear to the second highest again. Repeat the process of backing the barrel out a little at a time until there's enough tension on the cable to make this shift crisp and fast. Sometimes it's necessary to un-anchor the cable, pull it a bit tighter than you did the first time you mounted it, then re-anchor it. Note that every time you have to anchor the shifter cable, both the shifter and the chain need to be in the highest gear. After a while, knowing how much to pull the derailleur cable before anchoring it becomes more intuitive, but for beginners this may take some trial and error.
Once you've found the proper tension that allows the bike to shift from high to low, check that it shifts from low to high properly. If it doesn't want to jump down on to the high gear, you have slightly too much tension. Turn the barrel adjuster in clockwise a single indent and try the shift over. Repeat the process until you're shifting smoothly from low to high. The check again from high to low. You should be able to shift in both directions quickly and without skipping or over-shifting.
Repeat this process but now in the low gears. Shift all the way to the lowest gear (1) and try shifting to 2. The chain should drop into place quickly. Then shift back to 1 making sure it's properly adjusted. If your adjustments on tension in the high gears was properly done, you should be shifting well in the low gears and throughout the range of the cassette. If you're shifting properly from high to low in one area of your gear range, but not in another, it's possible your derailleur-hanger is bent. Unless you have the specific tool for straightening it, we suggest either replacing it completely or taking your bike in to your local bike shop for repair.
Cable Tension Break Down
A simple way to break this down is if your bike is slow to shift into a higher gear, your cable is too tight. If your bike shifts into higher gears fine but is slow to shift into into a lower gear, you cable is too loose. When you turn the barrel adjuster counterclockwise, you add tension to the cable. When you turn the barrel adjuster clockwise, it removes tension from the cable. Knowing these fundamentals should allow you to properly adjust the tension on your cable to get you shifting in both directions properly.
Fine tuning your limits. Now that you're shifting, it's time to dial in the limits of the derailleur properly. Shift the bike into the highest gear. While pedaling, use your left hand to manually push the derailleur into the middle of your cassette and quickly let go, allowing the derailleur to rapidly return to the highest gear. It should go right to the highest gear but not over shift and drop the chain. If the chain drops, turn the high-limit screw in (clockwise) just a tad and repeat this process until you stop over-shifting. If the chain stops just before dropping into the highest gear, turn the high-limit screw out (counterclockwise) and repeat the process until the chain drops into place.
Now, shift into the lowest gear. While pedaling the bike slowly in the stand, use your left hand to try and push the derailleur off the inside of the cassette. If the chain goes between the spokes and cassette, you'll have to turn the low-limit screw clockwise and repeat the process until you stop over-shifting. If the chain doesn't want to shift from 2 to 1 at all and you're cable tension is good, you need to turn the low-limit screw counterclockwise until it shifts into the lowest. gear.
Wrap It Up
Give all your hard work one last review. Do single gear shifts from low to high and back down, one at a time, making sure every shift is smooth, fast and precise. If the bike is slow in either direction, adjust the tension via Step Three until the bike is shifting properly.
You're ready for the trail and now you have a guide to general drivetrain maintenance to keep your bike running smoothly.
Stay tuned for more From The Workbench tutorials covering a variety of topics.