180mm rotor front 160mm rotor rear. But Why?

Hello all,

Im pretty new to all this and was looking at increaseing my rear rotors size to 180mm from 160mm. My logic being that I prefer to get my back wheel locking out when flying down a hill rather than my front wheel locking and me going a*se over t*t.
However looking on here and elsewhere it seams that alot of people have there front rotor at 180mm with their rear set at 160mm.

Am I missing something?

Thanks in advance

front brake is the main brake.

I seem to naturally favour useing my rear brake more. I think this stems from a fear of flying over my handlebars if im too eager with my front brake.

So I take it this isnt the norm?

When you brake, there is a weight transfer to the front of the bike giving the front wheel more grip. This means that the front brake does more of the work hence the ability to make the most of a larger brake. The back brake is used mainly for balance rather than out and out braking. A 160mm disc should comfortably lock a rear wheel anyway.

Have a look at most motorbikes. They have huge (often double) front discs and really quite small rears.

simple test you can do to illustrate the point, without sitting on the bike roll the bike forward and see how much force you can apply to each brake before the wheels lock up.

No it is not the norm. The majority of the braking should be on the front. Check out any large motorcycle. Two big discs on the front and one small on the rear.

Front brake is your friend but not during cornering.

Sounds like I need to grow some balls then! Learn to love the front brake.

Thanks for the answers it does make sense now.

Thanks to Matthew h for explaining it so a newb can understand!

Same with cars – and as you only have one brake pedal the bias is heavily frontwards. Just switched from 160/160 to 183/160 and it’s a nice improvement, less locking up at the back, more controlled. If you under-rotate, drop your heels and keep your weight pushing through the pedals you’ll be much less likely to go over the bars.

Whats the differance between 180mm and 183mm rotors? (Dont say 3mm!)

Whats the point of the two differant sizes?

It’s just different manufacturers having slightly different standards.

Grip is compromised when braking and “gone” when locked up. In an ideal works you don’t want either wheel to lock up.

As you weight transfer goes forward during braking, the rear of the bike gets “lighter” and therefore its mor likely the rear wheel will lock. Having a smaller and (arguably) less powerful rotor on the rear negates the ease of locking up the rear.

However, with modern systems that physics is negated slightly as 160 brakes are so powerful today that much more rider input to judge the anount of braking force not required to avoid lockup it needed – but it works on the simple premise that equal force is applied on the front and rear levers during a braking moment.

I have hope mono minis, which would i need or doesnt it matter?

Whats the differance between 180mm and 183mm rotors? (Dont say 3mm!)

I have hope mono minis, which would i need or doesnt it matter?

The answer is 3mm, it’s just different manufacturers making slightly different sized brakes, some are 185 as well. As a rule if you stick to components from 1 manufacturer they’ll work together nicely, the exception being hope who will make you whatever sized disk you want, so if buying 2nd hand hope bits make sure you know what size you need and it’s what you’re getting.

Also some rotors are not the size they say they are, for example hayes 6″ (150mm) rotors are in fact 160mm, so the sizes are only nominal anyway.

I’m using hope X2 callipers, shimano addapters and aligator rotors and 180mm is fine.

I think I will just get Hope stuff to keep it simple.
Thanks for the advice

I used to comfort/trail brake with the rear brake until Jedi broke my habit. The rear brake just makes the bike go sideays, and you lose control instead of gaining it. With a measured approach with the front brake you can hit the braking zone a lot faster and still make the corner. Well that’s what I found anyway.

Rear brake is for slowing down and front brake is for stopping.

I’m using a 225mm rotor on the front brake over here 🙂

185mm on the back..