6 DIY HOME-MAINTENANCE STEPS
Beyond the normal ABCs
Bike shops have been busier than ever during the recent boom in
popularity of mountain biking. With supplies being limited, bikes and
components are highly sought after, and some shops experiencing long wait times for maintenance. In light of this, we thought it would be helpful to cover some basic maintenance that can be done at home. This may require some cost up front for some essential tools, but it will save any mountain bike rider money and time in the long run. Let’s be real here; bike maintenance is a wide-ranging topic. Like most riders, we want to ride more, and spending a little time giving your bike some TLC will go a long way towards keeping your bike functioning well on the trails. First, we will cover the mountain bike version of the ABCs (air, brakes and chain).
CHECKLIST OF TOOLS MENTIONED:
• Bike-tire pump
• Shock/suspension pump
• Hex keys
• Torx keys
• Reliable measuring calipers
• Bike cleaning supplies
• Bike chain lubricants
• Chain-wear tool
• Torque wrench
• Bike stand
Running proper air pressure is important. More riders are now running tubeless tires that tend to lose a few pounds when sitting for a few days, but even if you run a tube, check your pressure regularly. Just like car tires, bike tires are labeled with recommended pressures. A reliable Schrader/Presta-valve bicycle pump is ideal, but it is just as important to know the tire size you are running, as pressures will vary. For example, in a 29×2.4-inch all-mountain tire, we typically run 23–25 psi; however, with a 26×4.0-inch fat tire, we’ve seen riders running 10–15 psi or lower. Before filling tires with proper air, inspect for potential cuts/tears, cracked sidewalls and bald spots. Replenish the tire sealant if it’s dried up. Sealant typically needs to be replaced every 2–12 months, with low humidity usually warranting more frequent intervals. If in doubt, check your sealant levels at least every six months.
Some forget that tires are not the only part of a mountain bike that can require air. You need to check the pressure in your fork and shock as well; however, before you do this, it’s best to refer to the torque section of this article to make sure everything is buttoned up. If all is properly secure, you are ready to start adjusting the air pressure in your fork or shock. You may recall our “Five Steps of Suspension Setup” in our May 2021 issue. While that article dives deeper into each step, there is a basic formula to follow. First, set the sag. It should generally be set between 25 and 30 percent on the shock and around 15 to 20 percent on the fork. From there, the rider can adjust the rebound and compression damping if applicable. Manufacturers’ setup recommendations can vary, so it’s worth taking a look to see what is recommended for your particular suspension components. Don’t take suspension setup for granted, as it is key for a rider to be confident and in control.
Squeezing your front and rear brake levers to make sure that the brakes engage properly and smoothly is crucial before a ride. More often than not, mountain bike brakes are hydraulic rather than cable-actuated. Be that as it may, some of our tricks and tips will work just the same no matter the brake style.
Besides regular bleeding or cable replacement, brakes and rotors will wear and need to be changed over time. Manufacturers provide minimum thicknesses for their rotors. As an example, Shimano recommends that its rotors, which start out 1.8mm thick, should be replaced when the braking surface has been reduced to 1.5mm. Just as with rotors, SRAM recommends replacing the brake pads when the total thickness of the backing plate and the pad material is under 3mm. Shimano says that when the pad material alone is less than .5mm thick, it needs to be replaced.
Have a bit of squeak? There is a chance the rotors/pads are contaminated with oils. If that is the case, you can sometimes remove the pads and sand them down a bit with high-grit sandpaper; however, if the oils have seeped too far into the porous brake-pad surface, then the rotors will keep getting contaminated, and new pads are in order. For a deep rotor clean, we typically use a dedicated brake cleaner to help keep our brakes squeak-free!
Pads and rotors are all clean but there’s still some rubbing noises? One of our biggest pet peeves is rotor rub, and we’ve attempted just about every trick to help realign a brake caliper and pad properly. To tackle this efficiently, we prefer to use the Hayes Feel’r gauge alignment tool. The tool has several functions—aligning pads, a testing surface for caliper pistons when pads are removed and a piston press. We mainly use the Feel’r gauge to create a gap between our pads and rotors for proper alignment.
For best performance, Shimano recommends bleeding brakes every six months. Depending on how much you ride, there is a chance that in that six months you will also need new pads. Replacing cables and housing is typically easier on a cable-actuated system. At any rate, this goes a bit beyond basic home-mechanic skills, so we recommend looking into what your brake manufacturer suggests, whether it’s learning how to replace cables or bleed a hydraulic brake system.
Keeping the bike clean is not usually high on most riders’ priority list, but at the very least, it’s important to keep your drivetrain clean, lubricated and inspected regularly. For the ultimate deep clean (usually done at the end of riding season), we’ve taken the crankset, chain, cassette and derailleurs off of a frame for a scrub. For the average rider, a dab of Dawn dish soap with warm water and a bike drivetrain brush can go a long way. If you ride in ultra-muddy conditions, we recommend making sure your drivetrain/bike is cleaned often to help prolong the life of your components. In our dry Southern California conditions, we do a more thorough cleaning of the drivetrain every two to three rides.
If your chain is looking dry, it’s time to apply lube! This is one of the easiest home tips and should be done regularly. When applying lube (note: wet or dry formula options depending on the environment you ride), apply small drops to every roller that is in between each plate link. The rollers are the most crucial part, since they come in physical contact with teeth throughout the drivetrain. From there, any remaining lube that is not primarily on the rollers can be wiped with a shop rag to make sure you avoid attracting more dirt. (Pro tip: We pedal backward for this, and we also run a rag over our derailleur pulleys to clean off any unwanted debris at this stage as well.)
At some point, a chain will stretch and not settle correctly onto your cassette, chainring or the derailleur pulley teeth. If the chain is not replaced when stretched past its recommended limit, it can cause damage to the other parts of the drivetrain. To avoid replacing more expensive parts, we like to use a chain-wear tool. This simple tool indicates when a chain reaches wear of either 0.5 percent (get a new chain) or 0.75 percent (cassette and chainring might be worn as well).
GOING BEYOND THE ABCs
Now that we’ve covered the basic ABCs (air, brakes and chain), let’s talk about another task to do at home. It is a popular belief that vibrations can cause fasteners to come loose over time; however, the most common reason a threaded fastener comes loose is that it wasn’t tightened properly when initially installed. Before going wild with your Allen (hex) and Torx keys on your bike’s fasteners, it is important to note that there are certain nuts and bolts (stem, brake caliper, linkage hardware for example) that may require a thread locker. Or, on some fasteners, it’s better to use grease. It’s always best to check with the component or frame manufacturer to see what’s specified. Grease has two key functions: First is to keep key components moving and prevent water from entering. Second is to protect places of static metal to metal contact from seizing up or “cold welding” (pedal threads, bearings, axles, seat tube, etc.). Yes, grease and lube are two different things and have different applications. Thread locker prevents loosening and also prevents corrosion.
When it comes to snugging up bolts, there is nothing on a bike that needs to be tightened with excessive force. This isn’t a car after all, so parts are much smaller and more delicate. There are some simple tools that can be used for most applications, but be warned that there are also some ridiculously specific tools needed for certain jobs. As a simple rule of thumb, any fastener should be tightened as tight as possible without the failure of the thread or the component parts. This means the weakest part of the joint determines the limits of tension, which leads us to the topic of torque specs.
Each fastener is designed for a certain range of tension (torque). Too much tightening will deform the threads or the parts. Too little preload will mean the fastener will loosen with use. Most amateur wrenches tend to make the mistake of over-tightening small fasteners like stem bolts and under tightening large ones like crank bolts. The common unit used to measure torque is the Newton meter (abbreviated N/m) or inch-pounds (abbreviated in-lb.). When you look closely at some of your components, you might notice indicators that give you an N/m rating. These markings can usually be found on your stem, crankset, rotors, pivot bolts and even the axles.
If torque specs can’t be found on or near a particular fastener, check with the bike or part manufacturer to get the proper torque specifications. To be consistent when changing parts or making adjustments, we like to keep a torque chart checklist that is filled in for the particular bike we are working with. Engineers will intentionally pick a thread size large enough to handle the anticipated stresses, but without indicators or markings, it’s always important to look up and confirm what the manufacturer recommends for the nuts and bolts of that component. There are several kinds of torque wrenches for bicycles, but you will typically see a beam or a click type. Regardless of the type, it is important to purchase a reliable option. A proper torque wrench is usually not the cheapest tool, but it is worth it to be confident that your components and accessories are tightened to the recommended torque. After all, no one likes breaking bike parts, especially the carbon bits, by going heavy-handed.
How to adjust a derailleur could be an article in itself. Not too long ago, mechanics had to take on the task of adjusting a front and rear mechanism. Now, 1x drivetrain systems are all the rage and are spec’d on most modern mountain bikes. The good news is that most rear derailleurs work in a similar fashion. Without going too far down the bike nerd rabbit hole, here are the steps to work through.
There are four fundamentals that have to work together for a rear derailleur to function properly. The H-limit (high-limit) screw restricts the movement from the highest gear (smallest cog), while the L-limit (low limit) restricts the movement in the lowest gear (biggest cog). The main purpose of the H- and L-limit screws is to prevent the chain from going into the spokes or into the frame. Then, there is the B-tension screw that adjusts the spacing of the guide pulley to the cassette cogs. The last aspect to consider is indexing. This is where a barrel adjuster is used to line up the guide pulley with the cogs so that each incremental shift lines up with each cog.
A. Derailleurs are a systematic setup. As such, if you reach a step and things still are not going correctly, go back and try again from the top. Start with the derailleur in the highest gear (smallest cog), and make sure there are no more clicks left at the shifter. It is also smart to turn the barrel adjusters fully clockwise with one full turn out (you’ll see why soon). Assuming the shift housing and cable are not in need of replacement, they can now be re-tensioned. Undo the cable anchor bolt, lightly pull on the shift cable, making sure it is aligned in the proper area, and while still holding tension, re-tighten the cable anchor bolt.
B. Most limit screws are marked, but if not, pick one and turn it in and out while watching the derailleur. At this stage (in the smallest cog), the H-limit screw will cause the derailleur to move. The idea is to use the H-limit screw until it sits directly below the smallest cog. The L-limit will adjust where the rear derailleur sits when in the easiest gears (biggest cogs). This will provide the most protection from the derailleur shifting the chain beyond the largest cog and into the spokes. The ideal adjustment for the L-limit will mean changing shifts to the lowest gear happens smoothly but doesn’t over-jump into your spokes. The guide pulley of the derailleur usually lines up slightly inboard from the cassette on the L-limit.
C. Remember those barrel adjusters that were turned in before adding cable tension? The process of indexing is to line up the guide pulley with the cogs so that each incremental shift lines up with each cog. The barrel adjuster allows us to make these adjustments. Starting in the highest gear, shift up to the next biggest cog. If the chain did not jump up to the next gear, add more tension by turning the barrel adjuster out (counterclockwise). From there, you can continue to shift up the cassette and make adjustments with one turn at a time to the barrel adjuster. The key idea to remember is that turning the barrel out (counter-clockwise) will add cable tension and prompt the rear derailleur to move to lower gears (bigger cogs), while turning the barrel in (clockwise) will decrease tension, moving the derailleur back down the cassette to a higher gear (smaller cogs). It will take some time to find the sweet spot where the derailleur moves to each gear smoothly.
D. Last, the B-tension can be turned in (clockwise) to increase the gap or loosened (counterclockwise) to decrease the gap. This is best checked when in the largest cog at the back. As a standard, there should be about a 5- to 6mm gap between the front of the derailleur’s top pulley guide and one of the top teeth on the cog. As we mentioned, this is a simple step-by-step guide that doesn’t dive into other variables. Don’t expect to get this right the first time. Our best advice is to start at the very beginning and try each stage again to get your shifting dialed in.
Now that you have some basic knowledge to make a fix at home in the garage bike stand, don’t let it be wasted when you head out for a ride! We end this “Garage Files” with a photo of our riding toolkit essentials that we carry. Whether it is a short or long ride, we like to keep our bikes performing at their best and to be prepared for the typical trailside issues that could come our way.