Test of the Ratio 12-speed gearbox kit


British company Ratio wanted to access the excellent range of SRAM 12-speed gears with shift levers without having to go wireless. So they took SRAM’s 11-speed road shifters and created a conversion kit that was followed by a whole lineup to cover all possible combinations of cassette and cable routing. As long as you get the right kit for the SRAM road groupset setup you’re trying to achieve (and Ratio has a very comprehensive and honest guide on their site to make that easy) and you’re patient with installing the various parts of the kit, it is an easy DIY job. We installed the Eagle and 10-36T road kits and so far could not be more impressed with their efficiency.

The parts included in the Ratio 12 speed gear kit for a road bike

Kits come with all the parts needed for your specific drivetrain setup (Image credit: Guy Kesteven)

Design and performance

The key component of the Ratio kit is the small metal 12-speed cam that you replace with the existing 11-speed cam on any SRAM 11-speed cable shifter (or any SRAM to 10 speeds if you also use the Ratio cable spool). The assembly is a bit complicated as you have to unbolt the shifter from the bars and it is much easier if you also give yourself enough free pipe under the tape to properly manipulate the lever or disconnect the lever from the brake line and remove completely, which is very painful for a hydraulic system. Once you have the shifter free, all you have to do is unscrew the grub screw that holds the shaft and shifter mechanism together, then remove it using the gear ratio. screws supplied in the kit. You then carefully remove the spool, remove the existing ratchet segment, and replace it with the one from Ratio. Click it carefully in the seventh position, then wiggle and slide the whole thing back into place, re-drill it with the axle, place the grub screw, screw the lever back onto the bar and in terms of shifting, you are ready to go.

12-speed reduction kit mounted on an 11-speed SRAM lever

The key is to swap out the existing cam on the shifters with Ratio’s 12-speed cam. (Image credit: Guy Kesteven)

Things get a little complex at the end, as you’ll have to figure out exactly what kit and / or derailleur you need to get everything to work. In the case of the wide range kit that I mounted on my tandem to handle an Eagle 10-52T cassette, it needed an Eagle compatible mountain bike derailleur of GX level or above and the wide 1×12 upgrade kit with a new aileron and barrel adjustment (a simple circle and Allen key) for the “Exact Actuation” wire ratio. As the road conversion works with a road rear mechanism, there is no need for a different spoiler, but you have to swap out the jockey wheels for those supplied by Ratio.

You might find that you have to juggle the machine screws a bit to get the right clearances and everything is going well, but once that is done you will hardly notice anything different in the feel of the shifting compared to the other. to an 11-speed system. The feel might be slightly sharper, but that’s probably because our Force shifters were older, so you don’t just upgrade to an extra cog (and potentially 10-44 / 50 / 52T cassettes. if you go for the mule / eagle), but you also get a sharper shift set-up. Although we’ve only been using the kits for a short time, we haven’t seen anything that suggests reliability is compromised either, but obviously as soon as you start getting IVs with your controllers or pulling the mechanisms apart, you will void your SRAM warranty if any remains. .

12-speed Ratio gear kit mounted on a road bike

Despite adding a gear, the shifting performance is not affected (Image credit: Guy Kesteven)


We’re big fans of the wider gear ranges and smaller gear changes offered by SRAM’s Eagle, XPLR and Road 12-speed series cassettes. Ratio lets you access those gains of existing 11 (and some 10) speed cable shifter with nothing more than a few small component swaps and a little patience and the results are impressive.

Technical Specifications: Ratio 12 Speed ​​Gear Kit

  • Price: £ 66.50 – £ 94.50
  • Weight: Negligible variation of items in stock
  • Options: 1×12 road, 1×12 wide rear or front cable outlet

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