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1×12 Compatibility Guide

To upgrade to 12 speed, you first need to work out which components you’ll need. Follow this guide to ensure you buy the right Ratio kit for your setup.

Ratio Upgrade Kits – Forward and rear cable exit

The Ratio 1×12 Wide Upgrade Kits are divided into two versions: Forward Cable Exit and Rear Cable Exit. To find out which Ratio kit you need, simply follow this rule:

If your chain stay/seat stay cable stop is over 70 mm from the dropout, use the 1×12 Upgrade Kit with Forward Cable Exit. If it is under 70 mm from the dropout, use the 1×12 Upgrade Kit with Rear Cable Exit.

To use the Forward Cable Exit, the cable stop must be over 70 mm from the dropout on the chain stay…
…or over 70 mm from the dropout on the seat stay. Otherwise the Rear Cable Exit version should be used
If the cable stop is too close, the cable will have to bend tightly. This causes drag which affects shifting
In the worst case, the cable may not be able to reach the Forward Exit derailleur at all

The derailleur cable generally exits mountain bike derailleurs (such as the Eagle™ derailleur) from the front. This leaves a smaller loop of cable to snag on undergrowth, but is incompatible with a number of road-orientated frames. In contrast, the derailleur cable on road derailleurs leaves from the rear – producing a large loop of cable that returns to the frame.

Mountain bike derailleurs generally have a forward-facing cable port, like the Forward Cable Exit kit
The cable leaves the Eagle™ derailleur with Rear Cable Exit kit like a road derailleur

The derailleur cable is secured to the frame with a ‘cable stop’ on the chain stay or seat stay. If it’s internally routed, there’s a similar point on the chain stay or seat stay where the cable enters the frame.

If this point is too close to the dropout (and therefore the derailleur) the cable may have to bend tightly to reach the derailleur, resulting in cable drag. In some cases it may be impossible to route the cable into the derailleur.

This frame is incompatible with Forward Cable Exit derailleurs: use the Rear Cable Exit kit

Shifters

The Ratio 1×12 Wide Upgrade Kits are compatible with all mechanical 11 speed SRAM shifters, whether for cable or hydraulic brakes*. This includes shifters from the Red™, Force™, Rival™ and Apex™ groups. As the 1×12 Wide kits are for 1x drivetrains, you can use 1x or 2x shifters. If you use 2x shifters, you can remove the left hand shift lever or use it to actuate a dropper post. The current S-700 Series™ 10 speed shifters are also compatible.

Most discontinued SRAM 10 speed shifters are incompatible with the Ratio kits as the cable spool in the shifter is a different design. This means that the Ratio ratchet cannot be fitted to these shifters.

Older 10 speed shifters are incompatible with the Ratio ratchet. These shifters can be identified by their white cable spool (image reproduced with kind permission from a Ratio 12 speed rider)

However, there are a small number of 10 speed models that use the newer 11 speed cable spool. This plastic cable spool can be identified by its red colour. To our knowledge, these models include ‘new shape’ 10 Speed Red™ SB-RED-B1 and some versions of the ‘old shape’ 10 Speed Red™ shifters. If in doubt, please visually check that you can identify the cable spool as the red (colour) 11 speed version.

Some 10 Speed Red™ shifters use red 11 speed cable spools, meaning they are compatible
(Images reproduced with kind permission of a Ratio 12 speed rider)

Derailleurs

The 1×12 Wide Upgrade Kits are designed for SRAM Eagle™ derailleurs. The Forward Cable Exit version of the kit should be used with derailleurs from the GX™, X01™ or XX1™ groups*. SX™ and NX™ derailleurs are incompatible because the cable fins on these derailleurs cannot be replaced; this means they cannot be used with road shifters.

The Rear Cable Exit version of the kit should only be used with X01™ or XX1™ derailleurs*. The Ratio Rear Cable Stop cannot be fitted to GX™ derailleurs using normal bicycle tools. However, we offer pre-modified GX™ derailleurs in a bundle: 1×12 Wide Upgrade Kit + Rear Exit SRAM GX Derailleur.

Cassettes

Our 1×12 ratchets have been designed to provide optimum shift positions on SRAM Eagle™ cassettes. Some customers have had good results using alternative cassettes with similar sprocket positions; we will update our guidance on cassettes as we complete more testing.

You can add a SRAM Eagle™ cassette to your kit order here.

Chains

As a general rule, drivetrains will shift best when the chain and cassette are supplied by the same manufacturer. This is because shift ramps on the cassette are engineered to engage with specific chamfers on a given manufacturer’s chain. When upgrading to 1×12 you should ensure you use a 12 speed chain. Note that Shimano 12 speed chains are not compatible with other manufacturer’s cassettes and chainrings.

You can add a SRAM Eagle™ chain to your kit order here.

Chainrings

1×12 drivetrains should be used with 12 speed compatible 1x chainrings. Using a non-1x chainring could result in the incorrect chainline for your drivetrain and your chain falling off the ring.

Although we don’t recommend using 11 speed chainrings, the teeth on these rings are around 0.1 mm wider than the teeth on a 12 speed chainring. Once an 11 speed chainring is worn, the teeth may be narrower. A 12 speed chain on a new 11 speed chainring will not clear mud as effectively and could fall off.

*Please note that modifying these components may void the original SRAM warranty. Ratio Technology Limited is in no way linked to SRAM LLC

22 thoughts on “1×12 Compatibility Guide”

  1. Do you know if it’s possible to run a 12 speed Eagle shifter with a Force/Rival 1x rear mech and 12 speed road cassette (eg 10-33), using the longer cable fin from an Eagle mech? Looking for a cheap-ish way to swap my existing AXS-compatible road wheels between bikes without having to swap cassettes.

    1. Hi Joe. Unfortunately not. The fin would allow you to run the Force 1 mech with the Eagle 12 speed shifter, but the catch is that the road 12 speed cassettes don’t have the same sprocket positions as Eagle. They’re sufficiently different (the road 12 speed cassettes are variably spaced, on average closer together) that you won’t be able to get the indexing right across the cassette. I’m really not sure what to recommend I’m afraid, short of finding enough demand for us to produce a road 12 speed ratchet for an Eagle shifter!

  2. Hi, can the ratchet be compatible with S-700 10 speed shifter? It is stated that the ratchet is compatible with 11 speed S series but as far as I know, there’s no 11 speed S series shifters except for the flat bar version.

    1. Hi. Yes, we believe our our upgrade kit is compatible with the SRAM® S-700 DOUBLETAP™ 10spd shifter. However unfortunately we haven’t been able to check that exact model of shifter. If you try it and experience any issues please get in touch at info@ratiotechnology.com. We’d also love to hear from you if you try it and it works too.

  3. Hi,

    I have found several online resources claiming that all 9-12 speed chains have the same internal width of 2.2mm (or 2.18mm, depending on the source)… your article states that there is a 0.1mm delta between 11 speed & 12 speed chainring tooth widths, so why does this 0.1mm delta exist if the chain inner dimensions are the same? Or is the info I found on chain inner widths actually incorrect?

    The background for my question is that I have a SRAM Force 1 x 11 system with 10-42 cassette, and I have purchased an Eagle X01 12 speed derailleur. I want to switch to a 10-50 cassette, and I don’t really want to have to swap out the cranks, so it looks like I have two options:

    1) Use a Ratio conversion kit plus an Eagle 12 speed 10-50 cassette and 12 speed chain; the downside would be that I would be running the “wrong” chainring width for the chain

    2) Swap out the cable fin on my Eagle derailleur with the one from my Force derailleur, and use a non-OEM cassette, e.g. Garbaruk 11 speed 10-50; the downside would be the bigger gaps in the shifts compared to a 12 speed cassette

    1. Hi Simon. Unfortunately (as usual in the world of bikes) things aren’t quite that simple. There’s no standard for chain dimensions and no incentive for the big drivetrain manufacturers to maintain compatibility with each other or the numerous after-market component makers. The reason that their dimensions tend to converge is simply that they’re working at the limits of materials and manufacturing processes when they release the newest chain design.

      As a general rule, most of the width reductions between chain generations come from the plate thickness rather than the roller width. That means your 2.2 mm figure is roughly correct, but that the void in the outer link (the one occupied by the wide teeth of a narrow-wide chainring) does reduce between generations.

      The width of these teeth is an engineering decision made by the chainring designer: Wider is generally better for chain retention but worse for mud clearance. When they were new, the wide teeth of your 11 speed chainring were wider than those of a 12 speed chainring. However, even when new they weren’t so wide that an Eagle chain wouldn’t fit. If your 11 speed chainring has covered any sort of distance, it’s highly probable that the wide teeth have already worn down to be close to the spec width of a 12 speed chainring.

      In summary, we feel quite comfortable recommending 12 speed SRAM Eagle chains for use with 11 speed chainrings, particularly if the chainring has already seen some use. The last thing we want is for people to scrap perfectly usable chainrings! If there’s anything I can clarify, please ask.

      1. That’s very clear, thanks for the detailed explanation! I’m planning to place an order later, once I figure out whether or not I need the rear cable entry version (looks quite borderline on my Stigamata frameset, so I need to double-check). Hopefully shipping to the US is OK…

  4. Hi guys
    I have a “regular” GX eagle derailleur (not lunar), and have bough the rear entry upgrade kit for my gravel bike.
    Am I correct in that if I grind off the rivet holding the pulley wheel, this upgrade set could work on this derailleur?

    Thanks
    Brad

    1. Hi Brad, you’re correct that you can fit the cable stop if you remove the rivet first. We don’t recommend that you try to remove the rivet without experience using power tools; be aware that you could damage the derailleur (or yourself) and that the removal is not a reversible process.

  5. If I understand Exact Actuation correctly, if I have a Force 1 setup (11spd shifters, derailleur, chain, cassette), then to convert to 12spd, I would only need to swap to your ratchet? Assuming I also change the to the correct chainring, chain, and cassette (max cog size accounted for). I assume that the XDR cassettes (XG-1270 and XG-1290) are the same spacing as the Eagle cassette.

    1. Hi Russ. Unfortunately, the catch is that the road 12 speed (XDR) cassettes have significantly different sprocket positions to Eagle. The 1×12 Wide Ratchet won’t shift well on these cassettes. The good news is that we’ll be launching a 1×12 Narrow kit later this month, specifically for use with SRAM’s 12 speed road cassettes.

    1. Hi, the road 1×12 kit will launch later this month with the 2×12 version following after – either later in April, or in May. The difference between the kits will be new jockey wheels designed for 1x or 2x derailleurs.

    1. Hi Volodya. The 1×12 Wide Ratchet is designed for Exact Actuation shifters. As the SRAM Rival derailleur is already Exact Actuation as stock, it will pair with the ratchet to give you the correct shift positions for a SRAM Eagle cassette. However, please be aware that the Rival 1 derailleur does not have capacity for sprockets over 42 teeth in size. To use this derailleur with a 50 or 52t Eagle cassette you’ll need an aftermarket jockey cage, such as those available from Garbaruk: https://www.garbaruk.com/rear-derailleur-cage-for-sram-11-12-speed.html?category=15

  6. Hi – if I want to utilize the existing Sram Force derailleur for a 12 speed build using an ETHirteen 12 speed cassette or similar, do I need a cable fin or will the shifter with the Ratio 12 speed kit work with correct cable actuation with the original 11 speed force derailleur?

    1. Hi, as the Force 1™ derailleur is already Exact Actuation™, there’s no need to change the actuation ratio using a replacement cable fin. A Force 1 derailleur and a shifter with our ratchet will give you the correct shift positions for an Eagle™ cassette. If you’re using an alternative cassette, you’ll need to make sure that it’s compatible with Eagle™ and that the Force 1™ derailleur has capacity for the largest sprocket.

  7. Hi. Im going to get a kit shortly,(or perhaps wait for the road version!?) and thought id note that i have a 10 speed force shifter that has a red spool. Im hoping its going to work. In any case…your product looks awesome and if it doesnt i’ll use it on another bike im sure.

    Thanks

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