Upgrading my MTBs rear disc from 160 mm to 203 mm

2 minute read

Turns out my cycling style when on an MTB is quite intense on the rear brakes, so much that after only 130 km of using my new bike, the rear discs were already showing signs of overheating while the front ones were still shiny and with the original silver color.

Why only resize the rear ones?

This is a common misconception when upgrading brakes on an MTB. People usually tend to change the front disc as they think is the one getting the most “punishment” when on a trail. This is true for sudden stops and short braking events, but for most of the time the rear brake is the one doing the job.

Why is this? In my experience, when on a descent I always use the rear brake to control my speed and get more control on the front, this consistent friction at the rear for longer periods of time results in substantially higher temperatures, which leads to overheated brakes and ultimately losing braking capacity when you need it the most. This is being true for me in all the +100,000 km I’ve ridden in my life.

Another reason why I change the one in the back and not the front is quite simple: A 203 mm rotor provides a high level of braking force and, because the front fork is weaker, it will suffer from that extra torque. That’s dangerous. Instead, the rear fork looks quite strong.

Let’s do it

I only needed to purchase 2 things: the new 203 mm disc and one adaptor to install it.

The process is very simple so I won’t get into many details, there is a lot of great YouTube tutorials on this matter that will explain it better than me. I’ll limit myself to post the before and after of the bike. Enjoy!

The “before”

The “after”