203mm Rear Rotor on MTB

[wilhelm-S]

Hi There!

 

Has anyone tried a 203mm rotor on the rear brakes of a mountain bike.

 

My Specialized came out with 203mm rotor at the front and 180mm rotor at the back... but would it be possible to have a 203mm rotor at the rear?

 

I'm sure Ill need some spacer or bracket (similar to the front), but a larger rotor would give more braking power.

 

I use my rear brake 2 x often compared to the front one.

 

Anyone experimented with this?

[CJ Van]

Short answer: Yes, you can.  Just make sure you get an adapter for a 203mm rotor and not for a 200mm rotor.

 

Long answer:  If you ride fast enough or are heavy enough to justify a 203mm rotor at the back instead of an 180mm for more braking power you are maybe fooling yourself that you do not use your front brake that much.  Your front brake will give you much more stopping power. 

If you are indeed not using your front brake that much you should consider using it more to slow you down.  You will get more controlled braking by using both brakes and not just the rear.  Using only the back brake to stop you will probably just cause the back wheel to skid and not have enough tractions.

That is the reason that most bikes come standard with a bigger rotor at the front than at the back.

Remember, no skidding on the trails.

[Puncher]

Yup , I ride 203 front and back on my dh/enduro bike. You need an adapter for your frame though.

As an aside you should be using your front brake more - thats where most of the stopping power is generated and not from the rear. 

[wilhelm-S]

Thanks gents, good input.

 

It not that I prefer (choose) using the rear brakes more compared to the front ones... I see that my rear pads tend to wear 2x faster so that its evidence that I am harder on the rear brakes.

 

Then a again, the 180mm needs a harder squeeze to brake... and maybe thats why the wear quicker.

 

Ultimately, I want a 203mm at the back to be able to brake effectively with one finger - little effort... maybe an inexpensive way to use physics to my advantage ?

[Dirt Tracker]

203 front and back for me. Works brilliantly. 

[wilhelm-S]

203 front and back for me. Works brilliantly. 

 

Can you maybe share a pic of the bracket/spacer on your rear rotor setup?

[Simon123]

only on my DH bike.

[porqui]

If your rear pads wear quicker then it's not the rotor size but your braking - more braking needed up front. It's a mind set change that requires effort.

[stefmeister]

If your rear pads wear quicker then it's not the rotor size but your braking - more braking needed up front. It's a mind set change that requires effort.

 

Haven't thought this through exactly, but a bigger diameter rotor should/could also wear your pads quicker.

 

Rear brake pads tend to wear quicker, as you also use your rear brake more to throttle your speed.

[V18]

203f+r. I weight 115 on a skinny day and ride mostly gravity. On my gravel bike 160/160 is perfect. But that's a completely different story.

[Captain Fastbastard Mayhem]

Haven't thought this through exactly, but a bigger diameter rotor should/could also wear your pads quicker.

 

Rear brake pads tend to wear quicker, as you also use your rear brake more to throttle your speed.

Nope. Opposite.

Unless... pad wear is determined by pressure and amount of rotor passed through the pads... So it may be less, more or equal

[Dirt Tracker]

Can you maybe share a pic of the bracket/spacer on your rear rotor setup?

 

i will do when I get a chance but my frame is set for 180mm front and back and I just went and got a 180 >203 adaptor, bolted it on, bolted my calipers and went riding. 

[Dirt Tracker]

something like this but got it at Trail and Tar. 

 

https://www.rosebikes.co.uk/shimano-disc-adapter-180mm-to-203mm-disc-brake-front-rear-2664359

 

[stefmeister]

Nope. Opposite.

Unless... pad wear is determined by pressure and amount of rotor passed through the pads... So it may be less, more or equal

Bigger diameter rotor will travel faster, thus increase wear on the pads. Same same bigger tools cut or sand faster. No?

[Captain Fastbastard Mayhem]

Bigger diameter rotor will travel faster, thus increase wear on the pads. Same same bigger tools cut or sand faster. No?

Ja, but less force on rotor for same braki g power. So need to factor that in as well.

 

Increase in speed (more rotor through pad for given speed)

 

Vs

 

Less pressure for given braking power.

 

Would be interesting, but I'd gladly trade increased wear for better braking.

[stefmeister]

Ja, but less force on rotor for same braki g power. So need to factor that in as well.

 

Increase in speed (more rotor through pad for given speed)

 

Vs

 

Less pressure for given braking power.

 

Would be interesting, but I'd gladly trade increased wear for better braking.

Indeed you’ll have more torque exerted with the caliper placed further away from the pivot point (axle), therefore less power required. However you have two forces at play with the pads perpendicular to disc and angular momentum of the wheel and disc rotor.

It’s not static friction. It’s a bit more complex I think, but my brain is fried this week from migraine and earaches - so not too keen on frying it further [emoji23]