K2 / Proflex Riders Group

General => Tech Forum => Topic started by: bayarearider on November 21, 2003, 06:40:37 pm

Title: For the Disc folks..what size rotors are you runni
Post by: bayarearider on November 21, 2003, 06:40:37 pm

I have the option of using 165mm or 185mm rotors on my new build.  I am curious as to what size most of you guys are using on your rigs.  I know 160-165 is ideal for XC, but i can get 185 for the same price.  Will this be overkill?  what would you do?

hopefully i will be done by thanksgiving, that way i can update my gallery.  [smiley=laughing.gif] [smiley=laughing.gif]

Title: Re: For the Disc folks..what size rotors are you r
Post by: numbnuts on November 22, 2003, 12:32:13 am

I have 165's f & r and it is fine, did a long fast DH in torrential rain a couple of weeks ago and had no problem.The bigger rotors look cool and i suppose there is a reason why they're made and used other than that. I guess wt is a reason why smaller is better.

Title: Re: For the Disc folks..what size rotors are you r
Post by: Matno on November 22, 2003, 12:35:36 am

I run the original Avids, which I believe are 160mm. I can't imagine why you would need more power than that, but I guess some people actually do complain of brake fade... Then again, I'm not that big and never doubted the stopping power of my V-brakes either. The discs were just a way to avoid mud (and give me an excuse to make a cool adaptor...)

Title: Re: For the Disc folks..what size rotors are you r
Post by: Old Proflexer on November 22, 2003, 01:37:33 am

original 160's on the shimano xt disc - i'm 190 lbs

if i were to do it again, i'd seriously consider the 185's only for something different.  but, i have more than enough brake power as it is for xc and light duty downhill stuff.  if you're into componentry overkill, a 185 is a half step in that direction.  i guess that would be an 'agressive xc' build.

to once again echo matno's comments, the disc's to me are the alternative to the v's issues with mud and wetness (a common problem on my circuits) and i just love making things fit that wouldn't normally do so.

OP

yeah, why not.  i'd do the 185 on the rear where you'll use it the most and 160 or so on the front.  when doing a high speed double braking, i'm always telling myself
'right - rear, left - launch!' so i don't over power the front brake and do a 'left - launch!'
i'm inclined to say that modulation / feathering is more important on the front than the rear.  you can skid in the rear on occasion and work out of it but even a momentary lock up on the front end is not good.

Title: Re: For the Disc folks..what size rotors are you r
Post by: keen on November 22, 2003, 02:32:59 am

 160-165 should have plently if not more than enough stopping power for XC use. I currently run  Avid's 165's for aggressive XC, light downhill use. I get a little fade @ Downeiville or Mt. Diablo, other than that I have plenty of power and modulation. Loss of Modulation is the trade off w/ larger rotors. I have a Big Hit w/ 8" rotors that will stop on a dime but they are not forgiving. 8" rotors, on the trail, requires some thoughtfull applications or you will find yourself in an endo.

Title: Re: For the Disc folks..what size rotors are you r
Post by: Simon on November 22, 2003, 03:20:44 am

160mm front 140mm rear Formula B4's no problems with this set up,used mainly for XC with the occasional DH,not found a reason to change,loads of power no fade,Simon.

Title: Re: For the Disc folks..what size rotors are you r
Post by: bayarearider on November 22, 2003, 03:55:07 am

thanks guys

so no GO on the 185's?  In fact i already agreed to the seller that i will be picking them up tommorow with a load of other stuff.  I guess i'll just sell it off and get the 165's from another seller.

thanks for the replies

i am guessing the only downfall would be weight, and loss in modulation , but how much loss are we talking about here? 185 is still about 7 inches not quite 8 inches from which i think would be really overkill.  i am 180lbs  

Title: Re: For the Disc folks..what size rotors are you r
Post by: Matno on November 22, 2003, 04:23:09 am

I wouldn't worry about it one way or the other unless you're a serious weight weenie. I doubt the change in feel would be all that much different. (Uneducated opinion). Modulation can be adjusted at the levers with many mechanical brakes. Not sure about hydraulics.

I say just go for it if you have a deal. If you don't like them, you can always change later...

Keep in mind that different size rotors require different adaptors. Just another factor to consider...

Title: Re: For the Disc folks..what size rotors are you r
Post by: bayarearider on November 22, 2003, 04:23:42 am

I forgot to ask about adjustability.  I will be running the avid mech's, if i do decide to go with the 185 Front and Rear, can i compensate for loss in modulation by adusting the caliper to increase modulation?  I am unfamiliar with the adjustability features on disc brakes.

Title: Re: For the Disc folks..what size rotors are you r
Post by: Matno on November 22, 2003, 04:25:58 am

Two words:

SPEED DIAL.

Avid levers have modulation adjustment built right in, and it works quite well. I love mine! Pretty much everything about the Avid mechanical setup is easy to adjust. ENJOY!

Title: Re: For the Disc folks..what size rotors are you r
Post by: numbnuts on November 22, 2003, 07:03:57 am

If you've already got 'em stick em on and have fun