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Mountain Bike Blog



Brake disk rotor size upgrade 180 to 200mm, 160 to 180mm


In this blog I want to explain the quite simple process of upgrading an Avid Elixir 180mm front / 160mm rear to a 200mm front / 180mm rear.  I've done a couple of trial runs down my VERY steep street the additional stopping power is quite amazing.

Being a 110kg bloke who loves descending I've long considered upgrading my brakes from the stock Avid Elixir 5's.  It would seem logical to go for a serious downhill kit but unfortunately the budget didn't reach that far so instead I decided to increase my rotor size.

At first the rotor size upgrade seemed quite a daunting exercise but some tips from an online source and the brain power of my 16 year old son made the whole process quite simple. 

First and most importantly I only needed to buy 1 x adaptor/screw set and the 200mm rotor, which meant the upgrade was less than $100.

The most confusing part was trying to work out which adaptor to buy.  Rather than guess I sought the help of my not-so-local online bike shop.  Importantly I sent a link to the spec page of my bike - always a good idea because then the tech knows exactly what they are dealing with.

For my setup I needed a Avid 40 Post mount and screws.  The screws were needed as were all the other mounting parts current setup - so make sure you order a kit with screws or you will probably end up having to head out to your LBS. 

The new rotor came with mounting screws meaning the only bits left over were the 140mm rotor and the old rotor mounting screws.

The numbers in the notes below refer to the image.  Left is before, right is after.  Click on the image to see a full size version.

  1. The 180mm front rotor becomes the new 180mm rear rotor
  2. The front post mounting bracket becomes the new rear mounting bracket note the smaller end is at the rear and the bigger end at the front (I hope I got this right)
  3. The front post mount screws become the new rear mount screws
  4. The rear post mount screws become the new front screws that connect the brake calliper with the new mounting bracket
  5. The new 200mm front rotor
  6. The new 40P front mounting bracket and the 2 small screws that came with the mounting bracket

Step 6 was probably the most confusing.  If you look carefully you can see that the mounting bracket is screwed into the fork (step 6) and a different set of screws attach the brake calliper to the mounting bracket (step 4).

I spent more time realigning my callipers than the rest of the job.



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There are plenty of great websites out there with a wealth of information about Mountain Bike Trails,
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