Single Speed And Fixed Gear Chain Length: How Long Should It Be?

For single speed and fixed gear bikes, chain length is set mainly by chainstay length and sprocket sizes so that the wheel sits in the dropout with enough adjustment room to tension the chain correctly.

Unlike derailleur bikes where the derailleur takes up chain slack, single speed and fixed gear bikes rely on correct chain length and proper axle position to maintain tension.

How Single Speed Differs from Derailleur Bikes

Feature	Single Speed/Fixed	Derailleur Bike
Chain tension	Set by axle position	Set by derailleur spring
Dropouts	Horizontal or adjustable	Vertical
Chain slack tolerance	Very low	Moderate
Gear changes	None	Many

The key difference: you must get the chain length exactly right because there's no derailleur to compensate.

The Basic Principle

Your chain length must allow the rear wheel to sit:

Not too far forward (chain too tight)
Not too far back (chain too loose)
Ideally in the middle of the dropout adjustment range

This gives you room to adjust tension as the chain stretches over time.

Calculating Single Speed Chain Length

The Formula (Modified)

For single speed bikes, the standard formula simplifies because there's only one gear:

L = 2 × C + (F + R) / 4 + 0.5

Where:

L = Chain length in inches
C = Chainstay length in inches (with wheel centered in dropout)
F = Front chainring teeth
R = Rear sprocket teeth

Note the +0.5 instead of +1. Single speed bikes need slightly less slack.

Example Calculation

Track bike setup:

Chainstay length: 390mm (15.4 inches)
Chainring: 48T
Rear cog: 17T

L = 2 × 15.4 + (48 + 17) / 4 + 0.5
L = 30.8 + 16.25 + 0.5
L = 47.55 inches

Number of links:

Links = 47.55 / 0.5 = 95.1

Since you need an even number, this could be 94 or 96 links.

But wait - the exact number depends on your dropout adjustment range. Read on.

The Dropout Position Method (Recommended)

The calculation gives you an estimate, but the practical method is more reliable:

Step 1: Install Wheel in Center of Dropouts

Position your rear wheel so the axle sits roughly in the middle of the horizontal dropout slot.

Step 2: Wrap Chain Around Gears

Thread the chain around the chainring and rear cog (no tensioner needed).

Step 3: Pull Chain Ends Together

Pull the chain ends together with no overlap:

If they just meet or barely overlap: Perfect - this is your length
If there's a gap: Chain is too short for this gear combo
If there's too much overlap: You can shorten the chain

Step 4: Account for Chain Tensioning

The chain should have about 12mm (0.5 inch) of vertical play at the midpoint between chainring and cog when tensioned correctly.

Understanding Dropout Types

Horizontal Dropouts (Track Ends)

The most common on fixed gear and track bikes:

Axle slides forward/backward in a slot
Full adjustment range for chain tension
Must use chain tugs or careful positioning

Typical adjustment range: 15-25mm

Sliding Dropouts

Common on modern steel frames:

Whole dropout assembly moves
Often has more adjustment than traditional horizontal
May include derailleur hanger option

Typical adjustment range: 20-35mm

Vertical Dropouts with Tensioner

Some single speed bikes use:

Standard vertical dropouts
Chain tensioner or eccentric hub
More forgiving of chain length

Eccentric Bottom Bracket

Another solution:

Standard dropouts
BB shell rotates to adjust chain tension
Found on some commuter and cargo bikes

The Half-Link Solution

When you can't get the right tension with full links, half-links save the day.

What is a Half-Link?

A half-link is exactly what it sounds like - a link that's half the length of a standard link (0.25 inches instead of 0.5 inches).

When You Need Half-Links

Chain is too loose with X links but too tight with X-2 links
You're running an unusual gear ratio
Your frame has limited dropout adjustment

How to Use Half-Links

Determine how many full links you need
If you need to add or subtract half a link of length, use a half-link
Half-links can be purchased separately or some chains include them

Note: Some people prefer to avoid half-links as they can be a weak point. If possible, adjust your gear ratio to work with full links.

Common Gear Ratios and Chain Length

Track/Fixed (15" chainstay)

Chainring	Cog	Ratio	Approx Links
48T	17T	2.82	94-96
46T	16T	2.88	94-96
49T	17T	2.88	96
48T	16T	3.00	94-96

Urban Single Speed (16.5" chainstay)

Chainring	Cog	Ratio	Approx Links
44T	18T	2.44	98-100
42T	17T	2.47	98
46T	18T	2.56	100
44T	16T	2.75	98-100

BMX Style (14" chainstay)

Chainring	Cog	Ratio	Approx Links
25T	9T	2.78	82-84
28T	10T	2.80	84-86
30T	11T	2.73	86-88

Adjusting Chain Tension

Proper Tension

12mm (0.5 inch) vertical play at chain midpoint
Chain should not be guitar-string tight
Should not sag significantly

Signs of Incorrect Tension

Too Tight:

Tight spots as crank rotates (indicates bent chainring or cog)
Premature bearing wear
Stiff pedaling at certain positions

Too Loose:

Chain drops off
Skipping under power
Noise and vibration

Converting to Single Speed

If you're converting a geared bike to single speed:

Using the Existing Chain

Remove derailleur
Shorten chain significantly (often 15-20+ links)
Use the dropout method to find correct length

Common Conversion Challenges

Vertical dropouts require chain tensioner
May need to try different gear ratios for good chain line
Original chain may be too worn to reuse

Tips for Fixed Gear Riders

Safety First

On a fixed gear, you cannot stop pedaling. A chain that breaks or derails is dangerous.

Check chain tension before every ride
Inspect chain for wear regularly
Replace chain at first sign of stretch

Skid Wear

If you skid to slow down:

Chain wears faster on fixed gear
Certain gear ratios wear the chain more evenly
"Skid patches" are worth considering for cog selection

Use the Calculator

Our Bicycle Chain Length Calculator works for single speed bikes too. Enter:

Your chainstay length (wheel centered in dropout)
Chainring size
Cog size

Then fine-tune using the dropout method.

How To Calculate Bike Chain Length - General method
Bicycle Chain Length Formula - The math explained
Is Your Chain Too Long or Too Short? - Troubleshooting
How To Shorten A Bike Chain - Chain tool guide
Bike Chain Length Chart - Reference tables