Compatibility calculator for bicycle drivetrain components – check rear derailleurs, cassettes, and shifters from Shimano and SRAM

Bicycle Drivetrain Components Compatibility Calculator (Shimano, SRAM)

Select the drivetrain components you want to use on your bike, and the calculator will show whether they are compatible.

The calculator results are not officially verified or endorsed by component manufacturers; it simply compares how well the components match each other based on technical parameters (cable pull, derailleur ratio, sprocket pitch, capacity, cassette sprocket size).

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Components Compatibility Table

This table lists the parameter values used in the calculator that affect drivetrain component compatibility – shifter cable pull, rear derailleur ratio, and sprocket pitch.

Why do some values differ from those found online?

You can find a lot of different information online regarding cable pull, derailleur ratios, and sprocket pitch. But these values aren’t always accurate for several reasons:

• First, it’s extremely difficult to measure these values precisely using regular tools like rulers or calipers. Even small errors – tenths of a millimeter – can have a significant impact.
• Second, it’s often unclear who performed the measurements, how they were done, and what equipment was used. These numbers are frequently revised and may differ between sources.
• Third, values often change inconsistently across the shifting range – especially at the extremes of the shifter’s travel.

For example, let’s say we want to measure cable pull on an 11-speed Shimano Deore shifter. At first glance, it seems logical and more accurate to measure the total cable travel between the first and last gears and divide by 10 shifts. But the issue is that the cable pull at the first and last shifts is usually significantly larger than the average in the middle. So it’s more accurate to exclude those outliers.

This is a screenshot from a video showing measurements from the Booth’s Bike Projects channel, where the author uses specially designed tools to take more precise measurements:

Here we see that the average cable pull (excluding extremes) is ~3.4 mm, although it’s commonly stated that 11-speed Shimano MTB shifters have a cable pull of 3.6 mm. This is likely because the full range was measured with less precision.

And this isn’t an isolated case – many sources cite figures that aren’t entirely accurate. That’s why the values used in the table and calculator are, to the best of my knowledge, the most reliable ones available, based on trustworthy measurements, calculations, and data comparisons. However, not all values are fully verified and may still be adjusted as new information becomes available.

If you have relevant insights or data on this topic, feel free to share them in the comments or via the contact form in the “Contacts” section.

How to Use the Compatibility Calculator (Instructions)

The calculator consists of four blocks (Crankset, Rear Derailleur, Shifter, and Cassette), connected by lines that indicate compatibility based on the selected components. A green line and check mark indicate compatibility, while a red line and cross mean incompatibility. A block turns green if all connected components are compatible, red if none are, and gray if only some are compatible.

Below each block, you’ll see the parameters that influence compatibility. These are also color-coded to show whether the components match, and if not, the issue is highlighted in red. For example, the screenshot below (note that block placement differs slightly on mobile) shows that the derailleur’s capacity is insufficient to handle the total drivetrain capacity (from both the crankset and cassette). However, if a 1x or 2x setup with a 10T front difference is used, the derailleur capacity would be adequate, and all blocks would turn green.

The calculator also checks whether the calculated gear pitch matches the cassette pitch. A tolerance (error margin) of 3.3% is used. If the deviation exceeds this, an error is shown, since this could lead to serious shifting misalignments on some gears.

It also calculates the theoretical deviation between the derailleur guide pulley and cassette sprocket at the maximum gear change. For instance, a deviation of 0.27 mm means that if the derailleur is adjusted for the 1st sprocket, by the 10th sprocket it will be offset by ~0.27 mm. This is negligible and purely theoretical. If tuned to the middle sprocket (5th or 6th), the maximum deviation drops to ~0.15 mm (0.3 * 5).

Additionally, the calculator checks whether the selected cassette falls within the derailleur’s stated minimum and maximum sprocket size range. However, manufacturers don’t always list the true limits – just what is officially supported. The calculator includes either the official range or verified working values based on real-world data.

Finally, it checks if the number of shifter speeds matches the cassette. Sometimes this mismatch can be overlooked (if other parameters are compatible) – for example, if you’re installing a higher-end shifter with more clicks than needed. In that case, you just won’t use the extra click, and if you’ve properly set the derailleur limit screws, it won’t cause issues.

How Bicycle Gear Shifting Works

When you click the shifter, its internal mechanism tightens or loosens the shift cable. The other end of the cable is attached to the rear derailleur, which moves the cage and guide pulley across the cassette sprockets, thus shifting the chain.

The amount of cable pulled by the shifter and the derailleur’s cage movement are typically not equal (even with claimed 1:1 systems) and depend on the derailleur’s “derailleur ratio.” For instance, on a 6-speed Shimano drivetrain, the cable pull is ~3.2 mm, while the cage shifts ~5.5 mm. From this, the derailleur ratio is:

5.5 mm / 3.2 mm = 1.72

Or, knowing the cable pull and derailleur ratio, we can calculate the derailleur’s lateral movement:

3.2 mm × 1.72 = 5.5 mm

If this matches the sprockets pitch (the spacing between adjacent sprockets), then shifting will be accurate. But if the derailleur movement significantly differs from the pitch, shifting will be poor and the components won’t be compatible.

*However, there are two more compatibility factors to consider:

1. Derailleur capacity (listed in the specs) must match the drivetrain’s total capacity. For example, a triple crankset with 42/34/24T and a cassette of 11-34T results in a total capacity of (42 – 24) + (34 – 11) = 41T. The derailleur must have at least this capacity, or some gears will be unusable.
2. Derailleurs are designed to handle cassettes with sprockets in a specific size range (also listed in the specs). For instance, a road derailleur designed for 11-14T small and 25-30T large sprockets may not work with an MTB cassette with 11-42T. It won’t shift onto the larger sprockets, and under load, this could even damage the drivetrain.

If you have any questions, can’t find your derailleur or cassette, or want to share a working component combo from your own experience, feel free to leave a comment.