Twelve speeds, a 10-tooth start, and 360% of range.

The XG-1250 is what makes X-Range gearing work. Starting at a 10-tooth cog instead of an 11 lets SRAM use smaller chainrings without giving up top-end speed — which is the whole reason a 48/35 crank outruns a 50/34, and the reason a 42T ring is enough for gravel.

Cog sizes: 10, 11, 12, 13, 15, 17, 19, 21, 24, 28, 32, 36.

Read the spacing, not just the range

The useful thing about this cassette isn't the 36 at the bottom. It's where the gaps are.

The first four cogs step one tooth at a time — 10, 11, 12, 13. That's the range you live in on flat road and fast group riding, and single-tooth steps mean you can actually hold a cadence instead of picking between too hard and too easy.

The jumps open up as the cogs get bigger, which is exactly where you want them. Nobody is fine-tuning cadence at 32 teeth on a 12% grade — they just want a gear that lets them keep turning the pedals.

What this gives you on the bike

On a 2x 48/35 setup: 48x10 at the top down to 35x36 at the bottom. That's a higher top gear than a traditional 50/34 with an 11-tooth cog, and a lower bottom gear than most compact road setups ever offered. Close to 500% total range from a road drivetrain.

On a 1x 42T setup: 42x10 down to 42x36 — 360% of range, with a top gear that holds pace on pavement and a bottom gear near 1.2:1.

If you need lower than that, this isn't your cassette. A 36-tooth large cog is the practical limit for a standard road AXS rear derailleur. Riders wanting a genuinely low climbing gear for loaded gravel or steep sustained dirt want an XPLR cassette with a 44 or 46 large cog, which requires an XPLR rear derailleur to match.

You need an XDR driver body

This is not a preference. It's physics.

A 10-tooth cog is smaller than the diameter of a standard HG freehub body — the cog can't fit over it. SRAM's answer is XDR, a driver body designed specifically for cassettes with fewer than 11 teeth on the small cog.

Check your rear hub before ordering. If your wheels have an HG or Shimano-style freehub, this cassette will not mount, and there is no adapter that changes that. Most wheel manufacturers sell an XDR driver body as a replaceable part for their hubs — it's usually a ten-minute swap, but you have to buy the right one for your specific hub.

XDR vs XD: they look similar and they're not the same. XDR is 1.85mm longer and built for road hub spacing. If you already have an XD driver from a mountain wheelset, that won't work here either.

FULL PIN construction

Rather than machining the cassette from a solid billet, SRAM stamps the cogs individually and pins them together — 123 stainless steel pins holding the stack. It's lighter than a solid cassette at this price and stiffer than a riveted spider design.

The open architecture between cogs also sheds mud instead of packing it, which is why this cassette works for gravel as well as road. A packed cassette shifts badly and wears fast.

Nickel chrome plating on the cogs adds hardness for a longer service life and runs quieter under the chain.

You will need a SRAM Flattop chain

SRAM's 12-speed road and gravel drivetrains use Flattop chains, a different design from standard 12-speed chains. A Shimano 12-speed chain will not work. A SRAM Eagle chain will not work. A generic 12-speed chain will not work.

Compatible: SRAM Road Flattop D1 or Road Flattop E1.

What you'll still need

• An XDR driver body on your rear hub — verify before ordering
• SRAM Road Flattop chain, D1 or E1
• A 12-speed AXS rear derailleur rated to 36T
• A cassette lockring tool — the standard 12-spline type

Fitment

• Driver body: XDR only. Not compatible with HG or XD.
• Speeds: 12
• Drivetrain: 1x or 2x
• Max cog: 36T — confirm your rear derailleur is rated for it
• Chain: SRAM Road Flattop D1 or Road Flattop E1 only

Specifications

• Model: CS-XG-1250-D1
• Gearing: 10-36T
• Cog sizes: 10, 11, 12, 13, 15, 17, 19, 21, 24, 28, 32, 36
• Speeds: 12
• Total range: 360%
• Construction: FULL PIN — stamped cogs, 123 stainless pins
• Finish: Nickel chrome plated, silver
• Driver body interface: XDR
• Drivetrain configuration: 1x, 2x
• Chain technology: Road Flattop D1, Road Flattop E1

Installation

Standard cassette install with one caution: XDR driver bodies are aluminum on most hubs, and an over-torqued lockring will bite into them. Use a torque wrench and follow the value in SRAM's documentation. A little anti-seize on the driver splines makes removal much easier a year from now.

Replace the chain at the same time if the old one is worn. A worn chain on a new cassette will chew the new cogs quickly, and you'll be buying both again.

Full documentation is available in SRAM's service hub for this model.

OE product information

Not intended for retail sale. This is original-equipment product supplied for dealer service, warranty replacement, and complete-bike build applications.

OE product is the same component that ships on complete bikes — identical specification, identical performance. What differs is how it's supplied:

• Plain bulk or poly packaging rather than a retail box
• No printed manuals or quick-start guides — all documentation is available free from SRAM's service hub, linked above
• No retail hang tags or display materials
• Small-parts and hardware content may differ from the retail pack
• Components may show minor handling marks from bulk packing

Warranty. SRAM's consumer warranty program does not apply to original-equipment components. Warranty and defect claims on this item are administered by State Bicycle Co. Contact our support team with your order number. Wear is not a defect — cassettes are a consumable.

Original equipment service item. Supplied in OE packaging for dealer service, warranty replacement, and complete-bike build applications; not a retail-packaged consumer product and not intended for retail sale. SRAM consumer warranty does not apply to original-equipment components — warranty administration on this item is provided by State Bicycle Co. Requires an XDR driver body; not compatible with HG or XD freehubs. SRAM, Rival, AXS, XG, XDR, X-Range, FULL PIN, and Flattop are trademarks of SRAM LLC. State Bicycle Co. is not affiliated with or endorsed by SRAM LLC. Specifications subject to change without notice.