The Five Most Overlooked Bolts in Bicycle Maintenance

Introduction: When Was the Last Time You Checked Your Bolts?

“Bolts? Aren’t bolts just something you tighten and forget about?”

If that’s your answer, you might not realize that bolts on a bicycle gradually loosen over time under the influence of vibration, temperature changes, and stress. Most riders pay attention to stem bolts and seatpost clamps, but there are five bolt locations that are frequently overlooked—until they cause problems.

Number One: Bottle Cage Bolts

Why Are They Overlooked?

Because the bottle cage “looks stable.” You see it there every day, so you assume it’s fine. But in reality:

• Every time you pull a bottle out or push it in, lateral force is applied to the bolts
• Road vibration affects them continuously
• Taiwan’s rough roads accelerate loosening even faster

What Happens?

• Minor: The bottle cage rotates, and the bottle doesn’t sit securely
• Moderate: The bottle falls out mid-ride (my bottle! An NT$800 insulated bottle!)
• Severe: The bolt falls out and is lost, leaving the frame’s threaded insert exposed (affecting corrosion resistance and appearance)

How to Check

1. Shake the bottle cage by hand
2. There should be no play at all
3. Use a 4mm or 5mm hex wrench to confirm tightness
4. Recommended torque: 3-5 Nm
5. Bonus: Apply a small amount of threadlocker (medium-strength blue Loctite) to the bolts

Special Caution

Never overtighten bottle cage bolts on carbon fiber frames! The threaded inserts on carbon frames may use metal rivnuts, and overtightening can cause the insert to spin loose inside the frame—this is nearly impossible to repair.

Number Two: Cleat Bolts

Why Are They Overlooked?

Because cleats are underneath your shoes, out of sight. And many people install their cleats and never touch them again.

What Happens?

• Minor: The cleat shifts slightly, affecting pedaling efficiency
• Moderate: Cleat angle changes mid-ride, causing knee discomfort
• Severe: The cleat comes off, making it impossible to clip in, or even causing a crash

How to Check

1. Flip the shoe over and visually inspect the cleat
2. Try to move the cleat by hand—there should be no play
3. Check the mounting bolts with a 4mm hex wrench
4. Recommended torque: 5-6 Nm
5. Also check the cleat for wear

Special Note for Taiwan

Many Taiwanese riders walk a short distance after a ride (from where the bike is parked to the front door). Walking on tile or concrete floors in cycling shoes will quickly wear down the cleats and loosen the bolts. It’s recommended to use cleat covers or change shoes before walking.

Number Three: Computer Mount and Light Mount Bolts

Why Are They Overlooked?

Computer mounts and light mounts are usually secured with plastic or rubber straps, so they don’t get checked regularly. But:

• Vibration is the biggest enemy of computer mounts
• Computer mounts installed on carbon handlebars tend to loosen because of the slippery surface
• Some aluminum computer mounts use very small bolts

What Happens?

• Minor: The computer wobbles, making the data hard to read
• Moderate: The computer flies off mid-ride (an NT$5,000-15,000 computer disappears)
• Severe: The computer falls into the spokes and locks up the front wheel (yes, this has happened)

How to Check

1. Gently shake the computer mount—there should be no obvious play
2. Check whether the mounting strap has aged or degraded
3. For bolt-type mounts, check bolt tightness
4. Verify that the latch between the computer and the mount works properly
5. Recommendation: Use a safety tether to connect the computer to the handlebar

Number Four: Rear Derailleur B-Tension Screw

Why Is It Overlooked?

Because most riders don’t even know this screw exists. It sits next to the derailleur mounting bolt and is a small adjustment screw.

Its Function

The B-tension screw controls the distance between the derailleur guide pulley and the cassette:

• Too close: The guide pulley may contact the cassette sprockets
• Too far: Shifting response becomes sluggish
• Correct: Approximately 5-6mm gap between the guide pulley and the largest sprocket

What Happens?

• Shifting becomes rough (especially on the largest sprocket)
• Unusual noises from the rear derailleur
• The guide pulley hits the cassette, causing damage

How to Check

1. Shift to the largest sprocket
2. Observe the gap between the guide pulley and the cassette
3. Adjust the B-tension screw with a screwdriver
4. Set the correct gap according to the manufacturer’s instructions

Number Five: Shift/Brake Lever Clamp Bolts

Why Are They Overlooked?

Because they’re hidden under the bar tape and can’t be seen from the outside. Unless you replace your bar tape, you might not touch them for years.

Where Are the Lever Clamp Bolts?

Usually under or on the side of the rubber hood cover:

• Shimano: Peel back the rubber hood; the hex bolt is at the bottom of the brake lever
• SRAM: Similar location
• Campagnolo: You may need to remove the bar tape to see it

What Happens?

• Minor: The lever rotates slightly during hard braking
• Moderate: Lever angle changes, affecting feel and ergonomics
• Severe: The lever slides on the handlebar during hard braking, making it impossible to brake effectively

How to Check

1. Grip the lever and try to rotate or push it
2. There should be no movement at all
3. If it moves, peel back the rubber hood to find the clamp bolt
4. Tighten to the recommended torque (usually 6-8 Nm)
5. Always check this when replacing bar tape!

Bonus: General Bolt Maintenance Tips

A Torque Wrench Is an Essential Tool

Type	Range	Price	Best For
Ratchet (large)	10-60 Nm	NT$1,500-3,000	Pedals, cassettes
Ratchet (small)	2-15 Nm	NT$800-2,000	Carbon components
Preset	Fixed value	NT$300-600	Specific applications
Digital	1-50 Nm	NT$2,000-5,000	Maximum accuracy

Threadlocker Usage Guide

Strength	Color	Use	Removability
Low	Purple	Small bolts, frequent assembly/disassembly	Removable by hand
Medium	Blue	Most bicycle bolts	Removable with tools
High	Red	Rarely used on bicycles	Requires heat to remove

Dealing with Seized Bolts

Seized bolts (especially aluminum bolts in aluminum threads) are a common problem:

• Apply a thin layer of anti-seize compound during installation
• Or use carbon assembly paste (for carbon frames)
• Don’t use threadlocker where anti-seize compound should be used

Regular Inspection Schedule

Frequency	Check Location
Before every ride	Quick releases / thru-axles
Weekly	Stem, seatpost clamp
Monthly	Bottle cages, computer mounts, shift/brake levers
Quarterly	All bolts on the bike (using a torque wrench)
Every bar tape replacement	Shift/brake lever clamp bolts

Conclusion

Bolts are the smallest yet most important components on a bicycle. A loose bolt might just cause an annoying creak—or it could create a serious safety issue.

Develop the habit of regularly checking your bolts, invest in a torque wrench, and you’ll avoid most bolt-related problems.

Spending 10 minutes checking your bolts could save you NT$10,000 in repair costs—or more importantly, prevent an accident. Go check your bottle cage bolts right now.

Related Reading

• The Science of Bicycle Bolts: A Complete Guide to Materials, Specs, and Torque
• Ten Common Bicycle Maintenance Mistakes: How Many Have You Made?
• Adjust Your Rear Derailleur Yourself: No More Skipping Gears and Noise
• Bicycle Cleaning and Rust Prevention: Protecting Your Bike in Taiwan’s Humid Climate