Bicycle Drivetrain Builder

Apex 1 11-Speed Shifter/Ekar 13-Speed Derailleur/11-Speed Cassette

Shifter: Apex 1 11-Speed (SB-APX-B1)
Derailleur: Ekar 13-Speed (RD21-EK13)
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Speeds:11 Use these numbers on a website like gear-calculator.com to find gearing that suits you and is compatible with this combo.
Max Tooth: 44
Chain Wrap: 35

These combinations are not supported by the manufacturer. Use at your own risk.

Cassettes

Cassette Part Number Support
SRAM 11-speed sram-11-speed Not Supported
Shimano 11-speed shimano-11-speed Not Supported

Compatibility Analysis

Show Compatibility Analysis

Each click of the shifter will move the jockey by 3.69 mm on average. Manufacturers generally to target a cog pitch that is between 0.7% smaller to 6.9% larger than this number.

In practice, no groupset aligns the jockey wheel perfectly for every shift. Manufacturers generally allow the chain to make up to a 1.2° angle from the jockey wheel to the cog.

Pull Ratio: 1.28
Cable Pull: 2.88 mm
Minimum Cog Pitch: 3.67 mm
Maximum Cog Pitch: 3.95 mm
Maximum Chain Angle: 1.2°
Table of relevant compatibility numbers

SRAM 11-speed

Cog Pitch Versus Average Shift

The cog pitch of a SRAM 11-speed cassette is 3.72 mm, which is 0.7% larger than the average shift. This value is within the typical range for measured groupsets.

3.72 mm Cog Pitch 3.69 mm Avg. Shift Range 3.67 mm 3.95 mm
Average jockey wheel movement per shift (left) compared to average cog pitch (right). Compatibility range on the right.

Worst Case Misalignment

This combination with a SRAM 11-speed cassette puts the chain at up to a 0.7° angle to the cog. This amounts to a sideways difference of 0.40 mm between the jockey wheel and the cog. This value is within the typical range for measured groupsets.

0.4 mm 0.7° 1.2° max
Cog and jockey in the worst-case scenario of alignment.

(Positions and angles are exaggerated for illustration. Numbers do not include the free play resulting from the cog being thinner than the rollers.)

Cog Positions vs Jockey Positions

2024-12-08T18:15:30.756078 image/svg+xml Matplotlib v3.9.2, https://matplotlib.org/
Comparison between cog positions and jockey positions for each shift. Cog positions are measured from the outside of the dropout.

Shimano 11-speed

Cog Pitch Versus Average Shift

The cog pitch of a Shimano 11-speed cassette is 3.75 mm, which is 1.5% larger than the average shift. This value is within the typical range for measured groupsets.

3.75 mm Cog Pitch 3.69 mm Avg. Shift Range 3.67 mm 3.95 mm
Average jockey wheel movement per shift (left) compared to average cog pitch (right). Compatibility range on the right.

Worst Case Misalignment

This combination with a Shimano 11-speed cassette puts the chain at up to a 0.9° angle to the cog. This amounts to a sideways difference of 0.48 mm between the jockey wheel and the cog. This value is within the typical range for measured groupsets.

0.48 mm 0.9° 1.2° max
Cog and jockey in the worst-case scenario of alignment.

(Positions and angles are exaggerated for illustration. Numbers do not include the free play resulting from the cog being thinner than the rollers.)

Cog Positions vs Jockey Positions

2024-12-08T18:15:30.936853 image/svg+xml Matplotlib v3.9.2, https://matplotlib.org/
Comparison between cog positions and jockey positions for each shift. Cog positions are measured from the outside of the dropout.