BikesMachine

Bike Repair Guide

By Kristin Arzt

Bike Repair Guide

Bikes provide a fun, healthy, and sustainable mode of transportation, whether you are commuting to work or meeting up with friends for a group ride. Routine bike maintenance and proper repairs will keep your bike running in top condition. Below you will find some of the most common bike repairs—from fixing a broken chain to adjusting your handlebars.

Common chain repairs

Chains are made of pairs of outer plates and inner plates that are held together by pins. The chain ultimately engages the gears on your bike. If a chain is out of balance, your bike is likely unrideable. Here are some of the most common bike chain problems and how to fix them.

Fixing a slipped chain

Pick up the slipped chain and position it to the top of the correct gear while pedaling. Once the chain teeth are locked in place, slowly release the derailleur and push the pedal forward to move the back wheel. Continue pedaling until the rest of the chains are fit back into their original positions. Before you get back on your bike, shift to the lowest gear and continue pedaling. This movement should realign your chain and lock it back into place. Changing gears without pedaling can cause the chain to bind up, and should be avoided.

Fixing a broken chain

Fixing a broken bike chain requires a chain tool—a compact, universal multi-tool. Once you have your chain tool on hand, flip your bike upside down so that its wheels face up and it is resting on the seat and handlebars. Examine your chain and determine which end needs to be removed.

Place your chain tool into the groove at the spot you want to remove. Make sure to remove a pair of inner and outer plates from your chain so you can properly reattach it. Turn the crank on your chain tool to push the pin out of the chain, making sure you don’t push it all the way through. Next, feed the chain onto the sprockets and push the pin back in. Once it is in, your new link will be stiff, so work it back and forth until it loosens enough to bend around the gears.

Degreasing and cleaning a dirty chain

To degrease a chain, you will need a rag and cleaning solvent. We recommend using diluted citrus solvent at a 1:1 water to solvent ratio. Start by shifting your chain into the smallest sprocket on the rear wheel of your bike. Hold the top of the chain in place with one hand while firmly wiping the lower set of the chain with a damp rag soaked in solvent. Continue along the entirety of the chain.

Common tire & wheel repairs

There are a number of issues that you can confront between your tire, wheel, and tubes. These basic repairs will save you from getting stranded with a flat tube or misaligned wheels.

Replacing a tube

Remove the wheel and tire

If one of your wheels needs its tube replaced, remove the entire wheel from your bike, deflate the tire, and pull out the tube. You will need a tire lever, which is a small, mostly flat, plastic tool with a curved end. The tire lever will allow you to hook the bead, which is a thin wire cable embedded in the bottom of the tire that helps to seal the tire to the wheel.

Pull the tire to one side at the point completely opposite the valve, and try to hook the bead from underneath. Once hooked, you can slide the lever radially around the tire to pull it over the rim. Once one entire side is off, pull the other side off in the same direction. For large tires, this will be pretty easy, and it might be a bit difficult for smaller ones. You can pull the tube out from just one side at this stage to give yourself some more room to work with.
Inspect the tube

As you separate the tube from the tire, notice its orientation and placement. You will want to take time to inspect both the tube and the tire thoroughly. Check the tire for metal or glass that may have caused the flat.
Install the new tube

Once you are sure the tire is safe, take your new tube and inflate it until it is round in shape and confirm it holds air. Line up the valve of the tire and valve stem of your tube, then place the tube inside of the tire.
Reinstall the tire

Starting at a point next to the valve, push the tire bead inside the rim, and proceed along the entire wheel. The tire bead is the edge of a tire that sits on the wheel. Once the wheel and tube are on the wheel, inflate your tire slowly. As you inflate, make sure that the tire bead remains in place and that the valve stays straight. It is helpful to first inflate to 10-15 PSI, then go around the tire rocking it slightly back and forth. This will help the bead seat in its proper location. Finally, reinstall the bike wheel.

Patching a tube on the road

Find the hole

Remove your wheel and take the tube out of the tire. Find the source of the flat by pushing on the inflated tube. If it isn’t totally obvious, you can submerge your tube in water or spray the tube with water and watch for air bubbles.
Clean the hole and apply cement

Clean the area around the hole with an emery board or fine sandpaper. Once it is clean and dry, spread a thin layer of rubber cement in the area around the hole. Wait for the solvent in the cement to evaporate. It will take a few minutes. You can check if it has evaporated by smelling the area where it was applied. When it evaporates, you should not smell any alcohol.
Apply the patch

Apply the patch to the layer of cement so the hole is centered underneath. Place the deflated inner tube on a firm smooth surface and rub the tube to create a bond between the patch and tube. Remove the backing on the patch, then dust the area around it with a small amount of chalk, if available, to neutralize the glue. Insert the tube into the tire and reinstall the bike wheel.

Changing tires

Remove the tire

To change a tire, you will need at least one tire lever and a bike pump. Push both sides of the tire toward the center of the rim to loosen the bead. Insert one of your tire levers under the bead anywhere on the rim except right at the valve. If needed, insert your second lever about five inches away on the same side of the wheel. Continue to pop the bead out from against the wheel until you can run the level around the entirety of the wheel. Remove the second bead from the rim using tire levers as necessary.
Replace the tube

Now that you have removed your wheel, put your replacement tube inside of the new tire. Check for any recommendations on the sidewalls of your tire that state the tire orientation. It will likely have the word “Direction” printed on the tire with an arrow. Engage the valve stem into the rim and make sure that the valve is not at an angle. If it is a Presta valve, screw the valve nut onto the valve loosely to secure it to the wheel. Work one bead at a time around the rim. Once one bead is installed, make sure the tube is tucked all the way inside of the tire. See the section above for notes on how to replace a tube.
Install the tire

Install one bead at a time and start by working one tire bead onto the rim with your hands. Work the tube over the rim sidewall and inside of the rim. Install a second bead onto the rim with your hands or a tire lever. Check both sides of the tire to make sure the bead is properly set inside of the rim. Slowly inflate the tube to its recommended PSI.

Fixing a broken spoke

Remove the broken spoke

Spokes come in all different lengths and sizes, so make sure that your replacement spoke is the same size as your broken spoke. Begin by removing the wheel and tire. Move the rim tape to one side. From there, unscrew one side of your broken spoke from the rim. Remove the other end of the spoke by sliding it through the hub eyelet.
Install a new spoke

Once it is completely removed, slide the replacement spoke in. When properly installed, the spoke pattern should be consistent all the way around the wheel. Using a spoke wrench, tighten the nipple onto the spoke to match the same tension as the rest of the wheel. You can check the tension by plucking the middle of the other spokes on the same side and compare them to the sound of the new spoke. Finally, true the wheel, and re-install your rim tape and tire.

Realigning and truing a wheel

You can true a wheel by tightening or loosening the spokes. First, remove your wheel from the bike and tire from the wheel, and mount the wheel in a truing stand. If a truing stand is not available, the bike can be flipped upside down and the brake pads can be used as a rudimentary truing stand.

Use a spoke wrench to slowly adjust the tension of the spoke that you notice is out of alignment. You will only want to adjust the tension of each nipple one-half turn at a time, then check the deviation again. Repeat this process until your wheel is aligned. Your wheel is adequately true if it wobbles less than 1/16 of an inch.

Other common bike repairs

Bikes are mechanical structures with many moving parts. Below you will find some other common bike repairs and the simplest ways to fix them.

Fixing a loose seatpost

A loose seatpost is a sign that your post needs to be greased. Apply a thin coat of grease to the outside of the seatpost with your finger. Re-insert the post to your preferred height and clamp it in place. You can simply use standard bicycle grease if your frame and seatpost are made of steel, aluminum, or titanium. If you have a carbon fiber seatpost, use carbon assembly paste instead of grease.

Other possible reasons for a loose seatpost are a misused quick-release seatpost clamp, an untightened seatpost, or an incorrectly sized seatpost. Remove the seatpost and clean it thoroughly. If there is excessive rust on the seatpost, use a brillo pad or steel wool to clean it.

Tightening loose and aligning crooked handlebars

If you have threadless headsets, which is the more modern system, start by loosening your pinch bolts on the backside of your stem. Then, straddle your bike with an aerial view of your handlebars. Rotate the handlebars until they are lined up with the front wheel. Finally, tighten the pinch bolts.

If you have an older, threaded headset, the bolt will be directly on top of the stem. Loosen it, but don’t unscrew it completely. The anchor bolt at the bottom has a tendency to become stuck inside the fork, so it may take some force to move.

Adjusting and aligning a derailleur

Bikes have a small front derailleur and a larger rear derailleur, and both have various sprockets from which the chain can be rotated. To adjust your derailleur, first, mount your bike in a bike mount, or turn it upside down.

Set the limit screws

Move your bike into the highest gear and turn the pedals until the chain moves into the smallest cog on the cassette. Check that the top pulley of the derailleur is directly below the highest gear on the rear wheel. This ensures the high limit screw of the rear derailleur is properly set.

Next, pull on any exposed piece of the rear shift cable while pedaling to bottom out the derailleur on the low end. Check that the top pulley of the derailleur is directly below the lowest gear. This ensures the low limit screw is properly adjusted. In either case, if the derailleur does not move fully into the extreme gear, the limit screw needs to be loosened. If it travels too far, knocking the chain off the gears, the limit screw for that range needs to be tightened.
Tighten and adjust the cable

After the limit screws are properly adjusted, refit the gear cable by pulling it taut and tightening the securing bolt. If finer adjustments to the cable tensions are required, simply turn the barrel adjuster. Unscrewing the barrel adjuster tightens the cable, and screwing it in loosens the cable.