Running a SRAM 12-Speed Cassette on WHEELTOP EDS: App Setting, Chain and Calibration

This article sets out what we can confirm, how to configure it, and the points where it pays to be careful. It will not cover everything about every SRAM part, because we only write about what we know.

Speed count is a software setting, not a hardware one

WHEELTOP EDS derailleurs are not built for one fixed number of gears. The speed is set in the WHEELTOP app (free, iOS and Android), so the same rear derailleur can be set up for an 11-speed or a 12-speed cassette. In the app you open the RD tab, tap Flywheel settings and choose the speed count your cassette has.

Here is the detail that catches people out. The speed options in that screen are Shimano's, and there is no SRAM brand to pick. That is fine. If you run a SRAM 12-speed cassette such as a Force XG-1270, you simply set the app to 12-speed and carry on. It does not affect how the derailleur works. After that, do the initial calibration on the smallest sprocket (below).

Check the size limits first

Speed count is only half of compatibility. The other half is the largest sprocket your derailleur can handle, and that depends on the model and cage length:

• TX (road, drop bar): cassettes up to 36T.
• GeX (gravel, 1x only): 75mm cage up to 42T, 93mm cage up to 52T.
• OX 2.0 (mountain, flat bar, folding): 58mm cage up to 32T, 75mm up to 42T, 93mm up to 52T.

A 10–30T cassette, like the one a buyer asked about, is comfortably inside the TX limit on largest-sprocket size. If your cassette runs to 46T or more on a GeX or OX, you need the 93mm long cage.

Hub driver: the part that is easy to miss

The cassettes we sell in our full groupset kits are SUNSHINE-SZ units made for a Shimano HG freehub body. They do not fit SRAM XD or XDR drivers. That is about the cassette body, not the derailleur, but if your wheels have an XDR driver, check this before you order a kit with our cassette.

The chain: what is confirmed

We sell the CHOHO DSL hollow flat-top chain. The confirmation we have, from CHOHO's technical staff, is this:

• The 12-speed Z12-DSL works with SRAM AXS 12-speed cassettes and chainrings, and with Shimano 12-speed too.
• The 11-speed Z11-DSL is for Shimano 11-speed only. It does not suit SRAM.
• The 12-speed chain comes in 120 or 128 links and you cut it to length for your frame.
• The quick link in the box is single-use. Fit a new one whenever the chain is reopened.

If you are thinking of a different chain, check with us before you order. We have only confirmed the CHOHO chains above. The CHOHO chain listing has the lengths, weights and quick-link details.

Set-up steps once it is on the bike

Fit the derailleur, set the chain length, and check the hanger. The hanger must be straight, and the small tab next to the mounting bolt must sit on the step at the bottom of the hanger before you tighten the bolt, otherwise the derailleur will not swing back and forth properly. Then:

• Set the speed. RD tab, Flywheel settings, 12-speed for a 12-speed cassette.
• Calibrate on the smallest sprocket. Shift to the smallest sprocket, tap Next step, then nudge the guide pulley with the on-screen +R / −L controls until it sits directly under the smallest sprocket. Keep the cranks turning while you do this, and never calibrate while riding.
• Set the limit screws after calibration and chain tension. Run the smallest-sprocket screw in until it just touches, then back off a quarter turn, and repeat at the largest sprocket.
• Fine-tune each gear. If an up-shift or down-shift is uneven, adjust the fine-tuning distance on the RD tab, one gear at a time.

The fine-tuning screen is where most of the patience goes. One OX 2.0 buyer wrote:

A well built derailleur and shifter. Instructions weren't the easiest to understand for fine tuning and the new app has the fine tune adjustment + & - cut off the screen. Will use this weekend.

That buyer found the + and − fine-tune controls cut off the screen. If that happens to you, send us a message. The point of the process is to move one gear at a time and test it before moving on.

When a SRAM cassette skips in the middle gears

One OX 2.0 buyer this week had a SRAM PG1210 12-speed cassette that skipped an extra gear in the middle of the cassette, gears 7, 8 and 9, when shifting to a smaller sprocket. They had already fitted a new hanger with no change, and wrote that they find 12-speed SRAM very finicky to get right. They had ordered a Shimano 11-speed cassette and chain to replace it.

Our advice in that situation: if you have worked through calibration and fine-tuning gear by gear and a SRAM cassette still skips, a Shimano cassette is the better match for these derailleurs. After swapping, set the matching Shimano speed count in the app, redo the initial calibration on the smallest sprocket, and fine-tune each gear again. One more thing, so you do not chase the wrong cause: a little sideways play in the derailleur's parallelogram linkage is normal on a new derailleur, and it is not what causes skipping.

Which version should you pick?

• Road, drop bars, 2x: TX, up to a 36T cassette.
• Gravel or a single-ring road bike: GeX. Choose the 93mm cage for a wide-range cassette. The GeX groupset listing has the cage and cassette details. On UDH frames it is only partially compatible, so check clearance at the smallest sprocket after fitting the chain.
• Mountain, flat-bar, folding: OX 2.0, choosing the cage by your largest sprocket: up to 32T short, 34–42T medium, 46T and above long.

For further reading, see our compatibility guide and the app setup guide. If your specific combination is not covered here, send us a message before ordering and we will tell you what we know and what we do not.