# Rotor size change?



## janser23 (Apr 29, 2011)

is it possible to change rotor size on a bike if you buy a whole new kit? im not sure if every bike can only have a certain size rotor, or if they are interchangeable
Thanks!


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## mtbnozpikr (Sep 1, 2008)

janser23 said:


> is it possible to change rotor size on a bike if you buy a whole new kit? im not sure if every bike can only have a certain size rotor, or if they are interchangeable


That all depends on what is in the kit. If you are going to larger rotors you want to make sure that your fork is built to take the extra stresses that accompany such a change. You will also need appropriate adapters that fit to your fork and frame to put your caliper in the correct position to accommodate the larger rotor.


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## janser23 (Apr 29, 2011)

I have 203mm rotors now, I think that's the largets they make, I want to go down to a 160 mm. The kit comes with everything, so I guess I'm asking if downsizing is okay.


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## mtbnozpikr (Sep 1, 2008)

janser23 said:


> I have 203mm rotors now, I think that's the largets they make, I want to go down to a 160 mm. The kit comes with everything, so I guess I'm asking if downsizing is okay.


Believe it or not, 220mm rotors exist. Downsizing should be no problem but you will still need the correct adapter to put your caliper in the correct position to engage the rotor.


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## janser23 (Apr 29, 2011)

Will the stopping power be different? 
Thankyou for your help, not sure if these are dumb questions or not, just getting into dh this year


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## mtbnozpikr (Sep 1, 2008)

janser23 said:


> Will the stopping power be different?
> Thankyou for your help, not sure if these are dumb questions or not, just getting into dh this year


Stopping power will be less depending on what size you go to. Larger rotors=more power (I'll spare you on the mechanics behind this). I'm happy to help where I can but be careful because some are quick to criticize on this forum.


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## janser23 (Apr 29, 2011)

Alright thanks, would you recomen


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## janser23 (Apr 29, 2011)

Alright thanks, would you recomend just staying with the 203mm and just get new calipers and levers?


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## mtbnozpikr (Sep 1, 2008)

janser23 said:


> Alright thanks, would you recomend just staying with the 203mm and just get new calipers and levers?


You're not giving me much information to go by. Are you trying to get into serious DH? What kind of bike are you referring to? What kind of brakes are you running? What are you trying to accomplish by switching brakes (more power I presume)? Give some information and it will be much easier to help.


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## nmfly (Sep 28, 2007)

In general terms stopping power is directly proportional to rotor size. Think of the larger rotor being a "cheater bar" increasing the lever arm distance from the hub. Heat generation somewhat throws the straight forward impact off, but in general bigger is more braking, but also more weight.

Assuming you have excess braking capacity for your riding conditions - downsizing isn't neccesarily bad.


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## whoda*huck (Feb 12, 2005)

If you're getting new brakes and the mounting type is the same as the old ones (post vs. I.S.) you can use your old adapters and rotors. Rear post mounts on frames are usually set up to run a 160 w/o an adapter, I think it's the same for forks. I also think you'd regret dropping from a 203 to a 160 in the front.


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## NWS (Jun 30, 2010)

whodaphuck said:


> I also think you'd regret dropping from a 203 to a 160 in the front.


Ditto. I went from 183 to 203 to get more power up front. 160 sounds frightening.


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