The official gear upgrade is probably fine for most Nireeka backers, but if you are into serious climbing or high speed it is necessary to further upgrade the front chainring.
There is no option for multiple chainrings with a derailleur, but there are other pretty fancy things you can do. We did discuss them on the previous gear upgrade threads, but as we know now what we get as an official upgrade, it is time to recap and get it all together in this new thread.
Let's go through them:
Update: Going to be reworked. The biggest chainring the Nireeka can mount is the 38t you already get with the official upgrade.
Waiting for confirmation of BCD do work out options for better low gears. And waiting for bottom bracket details to check compatibility of planetary gearboxes for better high gears.
1. Change the front chainring
Go for aftermarket chainrings that are compatible and you get for very little money a little better low or high gears. Make sure however that you get one with wide and narrow teeth. These perform better, avoiding chain drops and this is especially important with a wide range cassette as the chain will have low tension in the high gears. You can get these chainrings anywhere online or in your local bike shop.
1.1 - 30t chainring for climbing
If I am correct, the Bolt Circle Diameter (BCD) is 104mm. This allows for the smallest chainring to be 30t.
1.2 - 42t chainring for higher speed
It has been confirmed that it fits and that it is the biggest one you can mount.
2. - Get an oval chainring.
Steve pointed out this is like getting a combination of 2t down and 2t up. It can be less or even more depending on how oval the chainring is. They work by alleviating the dead point when the cranks are vertical and giving you more speed on the most efficient moment when the cranks are horizontal.
There are opinions of all sort about oval chainrings. The early models did not convince but nowadays it looks like they worked it out. Check out this article.
2.1 - 30t Oval chainring for climbing
A 30t chainring gives you 28t-32t. If the BCD is 104mm that is the smallest you can mount.
1.2 - 42t Oval chainring for higher speed
A 42t chainring gives you 40t-44t. There are bigger ones, but the frame design only can accommodate a 42t.
There is a number of manufacturers of these chainrings. Here are just a few:
Garbaruk - 32, 34,36, 38, 40, 42 teeth - $42-47
OneUp - 30, 32, 34 teeth - $47-60
Absolut Black - 30, 32, 34, 36 - $57-74
Osymetric - 34 - $65
To be continued with the Planetary Gearboxes and more...