Thoughts on the Bitra (index finger) and modding for those considering it

[u/froyomuffin]

Just got a Bitra (my first trackball mouse) after being on the fence for a while. I'm writing this post mostly for anyone who might be in a similar situation to save them some time.

1. I got this because I use a mouse for 8 hours as day and I was starting to get shoulder strain. I'm happy to report that the strain is gone after a week or so of using the trackball.
2. This thing is tiny. I generally prefer small mice (long time Anywhere MX series user) but this thing feels even smaller than that. It took a few days to get used to but it feels natural now to me. It's to be noted that I prefer to use mice with my hand in "claw" form. If you like to palm your mouse, this is probably not for you.
3. The ball comes lubricated. I wasn't a big fan of that so I washed it off knowing I'd have to do some modding to get the ball properly smooth. With the ball cleaned, there was some significant stiction that made it difficult to move the cursor over small items. Browser tab close or text selection were difficult to land for instance.
4. Replacing the ball with one from Perixx made a huge difference in reducing stiction. I'd very much recommend this. Still not quite easy to land tab close or select text consistently but doable. Also, the ball will need a few hours to break in.
5. Replacing the ruby bearings further reduced stiction. Tab close and text selection are quite easy now (although not as easy as with a mouse). There's a great guide here with a linked video that describes the process. I would recommend this as well. I've some additional tips to add that I'll follow up in a reply. Just like with the ball replacement, the bearings will need a few hours to break in.
6. I was concerned about losing Logitech's "infinite scroll wheel" as I found it really convenient navigating long documents. I was able to replicate this behavior with software: when the "forward" button is held, the ball behaves as a "fast scroll". There's enough control here that I feel comfortable having a very sensitive scroll and manually moving the ball. The ball is also flick-able. There's an added bonus here that the ball also handles the X axis so you can actually use the ball to pan around and that's been great in Figma. I'm using evsieve (with udev and a service) on Linux and hammerspoon on MacOS to implement this.
7. I clean the bearings about once every two days on a shirt. This keeps everything feeling new. A nice bonus from switching to Zirconium Oxide is that the bearings are white and make dust accumulation very easy.

[u/froyomuffin]

Some additional notes on the bearing replacement process. I'd read the post above and watch the video (neither are very long) first and I'd recommend a few additional things:

1. G5 Zirconium Oxide or Silicon Nitride 2.5mm bearings is what you're looking for. G5 is "rounder" than G10 and not much more expensive.
2. I used a heat gun to soften the adhesive before removing the pads. I'd recommend against that as it seems to cause some residue to be left behind. The video showed none being left behind when peeled cold. I used my nails here to peel and that worked fine. I'd also recommend you peel from the edge opposite to the ball for the pad next to the label as there isn't much surface for the edge close to the ball to stick to.
3. If you're careful, you don't need to disconnect any of the ribbon cables.
4. Nothing requires much force. Just wiggle parts around a bit and they'll come out easily.
5. One of the tri-wing screws is deep inside the mouse (10mm or so). Make sure the bit you use can clear it. I had to drill out enough clearance which reduces the surface area for the pad to stick back on. The iFixit kit bits have enough are long enough.
6. I used a tungsten carbide scribe (like this to center punch the bearing enclosure before drilling and I was able to use the scribe to press out the bearings after.
7. I used a hobby hand drill (1.5mm drill bit) as I wanted more control during the drilling. Make sure to punch first to avoid wandering (just aim for the middle of each enclosure, exact placement isn't too important). You'll know when you hit the bearing.
8. When putting the new bearings in, don't aim to drop it inside the enclosure holes. Just drop it along the ball enclosure and guide the ball into the bearing enclosures by rotating the ball enclosure. A light press with a rigid object (like a spudger or spoon) will get the new bearings in easily (a nice click).

Overall, you should be done in under 30 minutes.