How to Choose a Cassette Gear Ratio? Complete Comparison of 11-28, 11-30, 11-34 for Climbing

Cassette Gear Ratios: Every Tooth is a Strategy

If the chainring determines your “big picture,” the cassette is the key to fine-tuning your pedaling rhythm. The arrangement of 11 or 12 sprockets on a cassette directly affects whether you can maintain an optimal cadence across different terrain.

Common Cassette Configurations Overview

Shimano 12-Speed (R7100/R8100/R9200)

SRAM AXS 12-Speed

Close-Ratio vs Wide-Range: The Core Trade-off

Close-Ratio Cassette (e.g., 11-28T)

Advantages:

• Small tooth jumps between sprockets (mostly just 1-2T), so cadence is barely interrupted when shifting
• Easier to find the “perfect” gear
• Ideal for steady output on flats and gentle climbs

Disadvantages:

• Largest sprocket is only 28T, which may not be easy enough on steep climbs
• Narrow gear range offers less flexibility to adapt to changing terrain

Wide-Range Cassette (e.g., 11-34T)

Advantages:

• The 34T large sprocket provides powerful low gears for climbing
• Wide gear range lets one cassette handle all kinds of terrain
• Paired with a 34T small chainring, you can achieve roughly a 1:1 gear ratio

Disadvantages:

• Larger tooth jumps at the big end (e.g., 27-30-34), causing noticeable cadence changes when shifting
• The middle section may lack some gear ratios you commonly use

Tooth-Jump Analysis: The Devil is in the Details

Using Shimano 12-speed as an example, let’s compare the tooth-jump patterns of each cassette:

11-28T tooth jumps: 1-1-1-1-1-1-1-2-2-2-2-3
→ Extremely dense in the first half, ideal for fine-tuning cadence on flats

11-30T tooth jumps: 1-1-1-1-1-1-1-2-2-3-3-3
→ Balanced approach; still dense in the mid-to-high speed range, with reasonable spacing at the big end

11-34T tooth jumps: 1-1-1-1-1-2-2-2-3-3-3-4
→ Slightly less dense at the small end, but the climbing capability of the 34T is a clear upgrade

Cassette Recommendations for Taiwan’s Terrain

Riverside Bike Paths, West Coast Flats

• Recommended: 11-28T or 11-30T
• Reason: Almost entirely flat; a close-ratio cassette lets you control your rhythm precisely
• Matching chainring: 52/36T works best

North Coast, Northeast Corner (Rolling Coastline)

• Recommended: 11-30T
• Reason: Frequent short climbs and descents; 30T is sufficient, while the close-ratio section maintains cruising efficiency
• Matching chainring: 50/34T or 52/36T

Yangmingshan, Fengguizui, Highway 106

• Recommended: 11-30T or 11-34T
• Reason: Moderate climbs; 30T is enough for most riders, but 34T offers more peace of mind for those with weaker legs
• Matching chainring: 50/34T

Wuling, Hehuanshan, Alishan

• Recommended: 11-34T or 11-36T
• Reason: Long, sustained climbs; a large cassette is your lifeline
• Matching chainring: 50/34T, or even 46/33T

Island-Wide Touring

• Recommended: 11-34T
• Reason: Island tours feature varied terrain, requiring the widest possible gear coverage
• Matching chainring: 50/34T is the standard setup for island touring

The Relationship Between Speed and Cadence

Using 700x25C tires (circumference approx. 2.1m) as an example, here are the speeds at different gear combinations at 90rpm:

12-Speed vs 11-Speed Differences

The biggest benefit of upgrading to 12-speed is having one extra sprocket within the same gear range:

• The gear density of an 11-speed 11-30T ≈ the gear density of a 12-speed 11-34T
• 12-speed lets you have both a wide range and reasonable gear density

This matters greatly for Taiwanese riders: in the past, you might have struggled between an 11-28T (dense but insufficient for climbing) and an 11-32T (enough for climbing but with big jumps). Now, the 12-speed 11-34T solves both problems at once.

Cassette Replacement Practicalities

Things to note when replacing your cassette:

1. Freehub compatibility: Shimano 12-speed requires a Micro Spline freehub; 11-speed uses an HG freehub
2. Rear derailleur capacity: Confirm the maximum cassette sprocket size your rear derailleur supports
   • Shimano RD-R7100: up to 36T
   • SRAM Rival eTap AXS: up to 36T
3. Chain length: A larger cassette may require a longer chain
4. B-Tension adjustment: A larger cassette requires adjusting the rear derailleur’s B-Tension screw

Cassette Weight Comparison

The weight difference mainly comes from the added large sprockets. For most riders, a 30-60g difference matters far less than getting the gear ratios right.

Key Takeaways

Core principles for choosing a cassette:

1. Better to have it and not need it: A large cassette installed but unused is far better than needing it and not having it
2. Think about it together with your chainrings: A cassette can’t be considered in isolation; you must calculate gear ratios in combination with your chainrings
3. Consider the routes you ride most: Choose a setup that covers at least 80% of your riding scenarios
4. Make the most of 12-speed’s wide range: Since 12-speed offers the advantage of dense gearing, don’t hesitate to choose a wide-range cassette

Taiwan’s terrain is characterized by climbs that are “short but steep.” Even if you mainly ride flats, the occasional bridge ramp or small hill still calls for an easy gear in reserve. Therefore, the 11-30T is the safest all-round choice for Taiwanese riders; if you frequently head into the mountains, go with the 11-34T without hesitation.

Related Reading

• Climbing Gear Ratio Selection: Compact vs Standard Full Analysis
• Bicycle Gear Ratio Selection and Drivetrain Matching Guide
• Gear Ratio Selection for Climbing Races: Chainring and Cassette Setup Recommendations Before Race Day
• Road Bike Chainring Tooth Count Guide: 50/34 vs 52/36 vs 46/33