Sunday, January 2, 2022

Fnhon DB12: SRAM GX AXS Shifter

For this project to convert the Fnhon folding bike from 11 speed to 12 speed, quite a number of components need to be changed. Starting from the rear hub (change to XDR freehub body), the cassette and chain, and also the rear derailleur, the next component is the shifter.

What I like about the SRAM AXS system is that I can mix and match road and MTB components freely, subject to some physical limitations of course. This concept is the same for Shimano Di2 components as well, but it gets a bit more complicated if you are using a front derailleur.

Normally, we start by choosing the cassette based on the type of riding (road or MTB). Then, the compatible rear derailleur is chosen (road based or MTB based). As for the shifter, you can choose either flat handlebar type or road drop bar type, depending on your type of bike.

Now, for the Fnhon folding bike, I will be using the Force AXS road rear derailleur, and I need to pair it with a flat handlebar shifter, which will come from the MTB AXS system. The compatibility chart below shows the compatibility across the different AXS components.

Looks a little complicated, but it also shows that many components are cross compatible.

I chose the SRAM GX AXS shifter, instead of the more expensive X01/XX1 version. I think the function is basically the same.

Such a big box for such a small component!

Here is the GX AXS wireless shifter, which is powered by a single CR2032 battery.

There is a function button and LED below, for pairing and adjustment purposes.

The lever is the unique part of this shifter, unlike any other shifters I have seen. It's like a rocker switch where you push it upwards or downwards with your thumb.

The same lever extends to the back of the shifter, where it can be operated by the knuckle of the index finger.

From the side view, it is clear that pushing UP on the top fin (left side) is the same as pushing DOWN on the rear button (right side), since they are connected as a single piece.

Toggling the lever operates the electrical switches behind. There is some lever looseness, which is not ideal, but not a deal breaker.

On the aluminium bracket, you will choose one of the two holes for mounting the clamp band, or directly to the Matchmaker brake lever. This  moves the shifter to the left or right, depending on your ergonomic preference.

If you are mounting a clamp band, having 2 holes is redundant as you can just shift the clamp band on the handlebar itself.

Weight without clamp band, but inclusive of the battery is 68 grams.

Weight of clamp band (included with shifter) is 11 grams.

Here is how it looks with the clamp band assembled!

Weight of complete shifter is 79 grams, which weighs in between an XTR and Deore XT Firebolt switch.

Just to make things more tricky, I decided not to use the provided shifter clamp band. Instead, I want to mount it on the XTR brake levers that I already have on the bike. I love the XTR brakes, as they have so much power that I only need to press lightly with one finger to stop confidently. For me, using high quality brakes is not about having more absolute braking power, but to reduce the amount of finger force needed to generate sufficient braking force.

Therefore, I need a third party adapter, to that I can attach the SRAM GX shifter (using Matchmaker mount) to the XTR brake lever (using I-Spec EV mount). I found one online by ZRACE, which does what I want exactly. Let's see if it works or not. If it doesn't work, the backup plan is just to use the clamp band instead.

Here it is! I think it should be called BL and SL integrator, instead of BR.

It comes with the special nut on the left for I-Spec EV brake levers, and a bolt as well.

This side will be fixed to the I-Spec EV brake lever.

This side will be fixed to the Matchmaker shifter.

The adapter weighs 11 grams, which is exactly the same as the stock clamp band.

Using the adapter on the right, instead of the stock clamp band on the left.

Adapter mounted to the SRAM GX shifter. 

To move the shifter sideways, I can either switch to the other mounting hole on the shifter bracket, or slide the adapter along the brake lever. I will try to find the optimum mounting position later on, when it is being installed onto the bike.

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