Now that I have a shock I am happy with, time to move on to my other unhappy, the rear brake. My bike currently runs 185/160. I am not happy with the 160 in the rear. Both the fork and the frame are IS mount. This tells me that I could run the front caliper mount and rotor in the rear. Correct? Can i just run the 160 up front(which I hardly use anyway)? This would save me money, but if its not considered safe to run 160/185, then I wouldnt do it. If I cant run the 160 up front then I will just upgrade the front to 203 and move the current front 185 to the rear. Thanks.
^^ what he said. You should be using your front brake more than your rear because it does most of your braking. For your setup, you will need an adapter for the rear in order to use the bigger rotor. You might be able to use the one you have in front now, but you'll need a different one for the 203 rotor later. 203 is bit overkill unless it's a DH or you actually need the stopping power due to being a bigger guy, 185/185 should be fine.
Try using that front brake more, it gives you more of an actual slowing sensation than a skidding/sliding one. Also, depending on your suspension design, riding the rear brake can effect how your rear wheel reacts to bumps, actually giving you less traction. I run a 203 in the front and a 185 in the rear on my all mountain bike, but I am a pretty heavy guy and I like the modulation (amount of fine control) I can get with the greater leverage of the bigger rotors. -Al
203 on the front and 185 on the rear seams to be pretty standard. A good rule of thumb is either matching rotor sizes front/rear, or a larger rotor on the front since the front brake is used more for slowing you down.
I run 203/165 and I've never been concerned about rear stopping power. However, going to straight to 203 on the front has been wonderful in terms of power and modulation. The rear for me is all about scrubbing speed and helping the front to stop.
Here's the solution to your problem: http://www.socaltrailriders.org/forum/market-place/41915-shimano-disc-brake-adapter-203mm.html Buy a 203 rotor for the front, an adapter for your rear to 185 and sell your 160. Need I say more?
For the OP.... your front and read adapters are different, so you would need adapters to do what your thinking. Now as others have said.... Use your front brake more, life will be better
+1 on DMTDB's post. IS mounts are standards, but different for front and back. I.e. - your 185mm mounting hardware is specific to the front. I believe some mounting hardware can serve as dual duty. I.e. 160mm front mount can also serve as 140mm rear mount, but make sure you know what you're putting on the bike. To answer a more generic question: Yes, you can run 160mm rotors up front without issue. You'd just need the proper mounting hardware. Heck, run 140s if you want. The question of "safe" should be individual to the front and the rear, not really in tandem. However, if you're using your rear brake more than your front, you might want to check your braking technique versus your equipment.
Actually. most all mtn bike forks nowadays will not allow you to run less than a 160 rotor, everyone is going to post mount now, and even with IS, there is almost zero room to go smaller than 160.
Brakes The more you rely on the front, the less rotor size you'll need in the read. In fact, going bigger will likely just cause your rear wheel to lock up more, as the leverage on the wheel from the caliper is greater (think of the radius of the rotor working as a lever on the wheel...). Add to that the fact that hardly any weight is on the rear wheel when braking (especially downhill), and a bigger rear rotor practically guarantees a skid. I'm with those who recommend you start using the front brake more, and don't put on a bigger rear rotor. Have you looked at motocross bikes and moto gp bikes lately? The rear rotors are tiny, because making them larger just makes the rear brake too powerful.
I would love to upgrade to 185 in the front but unfortunately my silly Dart3 fork rec max rotor is only 160. will I risk breaking the fork if I upgrade anyway? that's only if I can find an adapter for it
