Bike Gears Explained

Bike Gears Explained: What You Actually Need to Know

Bike gearing has gotten complicated with all the speeds and ratios flying around. As someone who was completely confused by shifting when I started cycling, I learned everything there is to know about making the clicking actually make sense.

Shifting gears confused me for way too long. All those numbers, the clicking, trying to figure out why harder pedaling didn’t always mean going faster. Eventually it clicked – literally. Here’s the explanation I wish someone had given me.

The Basic Concept

Probably should have led with this section, honestly. Gears change how hard you have to pedal to maintain speed. Lower gears = easier pedaling, slower wheel rotation. Higher gears = harder pedaling, faster wheel rotation.

The goal isn’t to be in the “right” gear – it’s to maintain a comfortable pedaling rhythm (cadence) regardless of terrain. Going uphill? Shift to easier gears. Going fast on flat ground? Shift to harder gears. Your legs should feel consistent effort while the bike does the work of translating that to appropriate speed.

The Mechanical Parts

Chainrings – The gear teeth attached to your pedals. Road bikes usually have two (big and small). Mountain bikes often have one.

Cassette – The stack of gears on your rear wheel. Typically 9-12 different sizes.

Derailleurs – The mechanical arms that push the chain between gears. Front derailleur moves chain between chainrings, rear derailleur moves it between cassette gears.

Shifters – What you push to change gears. On road bikes, integrated with brake levers. On mountain bikes, usually separate triggers or dials.

The Practical Application

When to Shift

Shift before you need to, not during the hard part. See a hill approaching? Shift to an easier gear while you’re still on the flat. Already grinding up the hill and can barely turn the pedals? Too late – shifting under heavy load is hard on the drivetrain and might not work.

How Many Gears

Modern bikes advertise 11-speed, 12-speed, even 13-speed. This refers to the cassette in back. More gears means smaller jumps between each, smoother transitions. It doesn’t make you faster.

Front chainrings (1x, 2x) determine range. 1x systems (single chainring) are simpler but have less total range. 2x systems offer more range but add complexity.

Gear Combinations to Avoid

Don’t run big-big (large front chainring with large rear cog) or small-small (small front with small rear). These cause cross-chaining – the chain runs at an angle that wears components faster and shifts poorly.

Instead, use the big chainring with the smaller half of the cassette, and the small chainring with the larger half of the cassette.

What the Numbers Mean

A 50/34 crankset means two chainrings: 50 teeth and 34 teeth. An 11-32 cassette means smallest cog has 11 teeth, largest has 32.

Gear ratio = chainring teeth ÷ cassette teeth. Higher ratio = harder gear. A 50/11 combination is much harder than 34/32.

You don’t need to memorize this. Just understand that more teeth in front and fewer in back = harder pedaling.

How to Get Better at Shifting

Practice on flat, empty roads. Shift through the full range. Feel how each gear changes the effort required. Notice when shifting feels smooth vs clunky.

Good shifting is anticipatory. Experienced riders shift constantly, keeping cadence steady while terrain changes. They rarely grind in too-hard gears or spin uselessly in too-easy ones.

Maintenance Basics

Keep your chain clean and lubed. Dirty chains wear faster and shift poorly.

If shifting becomes inconsistent – skipping gears, refusing to shift, clicking noises – something needs adjustment. Cable tension, derailleur alignment, or worn components might be the cause. Learn basic adjustments or take it to a shop.

Chains stretch over time. Replace before they wear out cassettes, which are more expensive.

The Bottom Line

That’s what makes understanding gears endearing to us cyclists who’ve figured it out. Gears are tools for maintaining consistent effort across varying terrain. Don’t overthink the numbers. Shift to keep your legs comfortable. Anticipate changes. Keep your drivetrain maintained. Everything else is details.