GARAGE FILES: CONVERTING TO 12-SPEED

CONVERTING TO 12-SPEED

Because of the increased demand for bicycles and interruptions in supply chains caused by the COVID-19 crisis, parts and accessories are becoming more difficult to find. Even our wrecking crew here at MBA has had trouble finding parts, such as proper brake pads, chains, hydraulic hoses and even tires for some of our builds. Be that as it may, we are also seeing an array of creative innovations in components to keep riders pedaling.

In this “Garage Files,” we cover some great ways for riders to change up their bikes. This article was inspired when we overheard a fellow rider say, “To use 12-speed, you have to buy everything that the brand specifies for the system to be compatible.” While this might be true for some systems, it’s not always the case. Let’s dive into some of the newer options we’ve found and see how they could work for your bike.

On most modern bikes with multiple gears, the freewheel is built into the rear hub and the whole assembly is called a freehub. Here we see the three most common freehubs for mountain biking currently:
(L to R) Microspline, XD and HG.

 

DO I NEED A NEW FREEHUB?

Lots of hub manufacturers offer the ability to change the freehub body. Currently, in the mountain bike world, we typically see three types: Shimano HG, Sram XD and Shimano Microspline. DT Swiss is a great example that offers conversions to the different styles mentioned; however, be warned that some hub manufacturers may not be as easy to deal with. Fair warning on what is coming up; this is going to go into some bike nerd lingo.

Let’s say you already have a Boost rear hub with a 1×11-speed cassette mounted to an HG freehub body. Now you want to put 12-speed to use. It is best to go with a dedicated 12-speed derailleur, shifter, cassette and chain. Typically, the newest SRAM 12-speed mountain cassettes require an XD freehub, while the latest Shimano cassettes use microspline. Now, what if you want to stick with the same rear wheel and not change the HG freehub? Luckily, there is a great 12-speed 11-52t option from Rotor that riders can use on their HG freehub body with SRAM’s 12-speed system. While we prefer the Rotor options to save the most weight, SRAM does offer an 11-50t HG-compatible option called the PG-1230. SunRace also produces an HG option with the MZ90 and MZX0 cassettes that have an 11-50t range.

The biggest trade-off when not utilizing a cassette intended for microspline or an XD freehub body is the highest gear. HG can fit an 11t, while the other two options only go to a 10t. The short answer is that there are now options so that you don’t need a completely new freehub or wheelset to run a 12-speed cassette.

Another mixed-brand example with TRP’s 12-speed derailleur combined with SRAM’s 10-50t cassette and a Shimano chain.

 

WHAT ABOUT THE DERAILLEUR/SHIFTER?

Most manufacturers of drivetrains would prefer that you stay in their ecosystem of products. Nonetheless, there are brands such as SunRace, Rotor and TRP that have engineered options to work with other brands. The biggest standout option (in our opinion) is TRP’s G-SPEC TR12 derailleur and shifter kit. Although the TR12 derailleur has a 50t max range, it can be used with e*thirteen, SRAM, Shimano and SunRace cassettes. This makes it very compatible with whatever the current bike is being upgraded to.

Rotor produces a 13-speed hydraulically actuated derailleur that can also be set to shift like its 12-speed cassette. Unfortunately, its 13-speed cassettes require a specifically designed hub that calls for a custom wheelset. On the other hand, the 12-speed cassette that Rotor produces is intended for HG, as we mentioned above.

DO THE CHAIN AND CRANKSET MATTER?

Most modern mountain bikes feature a 1x (one-by) drive system. This means they use just one chainring at the front (as opposed to two or three, which used to be the standard). This also means that there are crankset/chainring options for three different chain lines (142/148/157mm spaced hubs).

To get the best performance from your chain, experts recommend matching your drivetrain manufacturer to the brand of chain you will be running; however, this isn’t a must, as we’ve tested in the past. The main focus is having a chain that is made for the number of gears you are running. Although the shift performance might not be optimized, it will likely work just fine.

Box Components has created a 9-speed system that has a very similar range in comparison with SRAM and Shimano’s 12-speed options.

 

DO I NEED 12-SPEEDS?

While the large range and steps in between are what make 12-speeds so special, there are other worthy brands to consider to achieve a similar range. For example, Box Components is the first that comes to mind with its Prime 9 option. This is a nine-speed drivetrain that uses a cassette made for an HG freehub body with an 11-50t range. Not only are the nine-speed components rated to be more durable and have fewer teeth for saving weight, this also gives a rider the same gear ratio range he can get with a 12-speed. The kicker is that you must use a Prime 9 chain for this application, but any 10-,11- or 12-speed wide/narrow chainring is compatible.

Overall, we know there are some other nuances and bike-nerd specifics that will be brought up when swapping. Pricing can vary, depending on what you’d like to achieve with a swap. Although we didn’t touch on the budget, we realize that this could be the deciding factor that determines if a swap is even worth it. At the end of the day, this guide and info should give any rider a great starting point for looking at what we are currently seeing on the market in the forever-changing world of mountain bike drivetrains. 


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