Rotor size?

rlb

Well-Known Member
I'll be upgrading to disc brakes over the winter (probably BB7s) but I'm not sure what size rotors to buy. I know larger rotors will give more stopping power. Are there any other advantages or disadvantages to larger rotors (aside from weight)? Any other factors I need to consider? (I have the wheels, and my fork and frame are disc ready).

Thanks,

Rob
 

walter

Fourth Party
For your everyday general cross country riding, like your bike was intended for, 160 mm disks will be fine.
 

gtluke

The Moped
you can run a smaller one on the back, since it takes less effort to stop that tire anyway. my epic has the tiny one on it and it works great.
the bigger the rotor, the more touchy they get and the more mass you have to move around. not a huge deal but i have the normal sized one on the front of my epic and i've never fet underbraked.
 

VanDbtRiver

Well-Known Member
i weigh a buck60, 160mm front and back are fine for mech disc. if u r heavy i would think a bigger front rotor would be beneficial, otherwise,... hydros.
 

TJYeti

Knows about bikes
I found that going from a 160mm to a 185mm in front made a big difference in stopping power.Way better.I'm weighing in at about 195 with a full camelback.
 

Fogerson

Former Resident Nerd
I found that going from a 160mm to a 185mm in front made a big difference in stopping power.Way better.I'm weighing in at about 195 with a full camelback.

Ditto; I'm about the same weight as you and running 180/160 with hydros.

They say you'll loose some modulation as you go bigger, but I didn't notice anything significant in that regard.
 

ADZ

Member
I'll be upgrading to disc brakes over the winter (probably BB7s) but I'm not sure what size rotors to buy. I know larger rotors will give more stopping power. Are there any other advantages or disadvantages to larger rotors (aside from weight)? Any other factors I need to consider? (I have the wheels, and my fork and frame are disc ready).

Thanks,

Rob


I have been running 160 on my mountain bikes for the past 8 years and had no problems. i must say that i had BB7 for about five years and i was constantly tuning them, since i switch over to hydraulic brake all i have had to do is change the pads. I do have a set of like new Avid Juices 5 that i am going to be selling. they are on my new GF at the moment and will be taking them off within the week. it will only be the levers and calipers, so you will need to get rotors for them, but this will give you the option to run 185 on the front if you wish.
 

jdog

Shop: Halter's Cycles
Shop Keep
I'll be upgrading to disc brakes over the winter (probably BB7s) but I'm not sure what size rotors to buy. I know larger rotors will give more stopping power. Are there any other advantages or disadvantages to larger rotors (aside from weight)? Any other factors I need to consider? (I have the wheels, and my fork and frame are disc ready).

Thanks,

Rob

I would keep saving and go for some Hydros. Well worth it.
 

don

Well-Known Member
The Avid Juicy's ADZ is selling could be nice. I have a pair of the Juicy 5's and love them. Like JDog said - it's worth the little extra for hydro. Mech's have their place and can work well but I think the Hydros work and feel better.

Like many other's I think 160 rotors would work fine. I'm on 185's but I'm also over 200 and it's on lighter freeride setup. I'd start w/ 160 front and rear and if you find you're needing more power - get a 185 up front.
 

rlb

Well-Known Member
Are the calipers specific to the rotor size? Or do you need a new caliper bracket when you change rotor size?

I was reading about the Juicy 5s and somewhere I saw that you need to rebuild the calipers (ie change seals etc) yearly. However I coldn't find any support docs on the SRAM site to confirm this. I this true for all hydros? Thanks for all of the input.
 

ADZ

Member
Are the calipers specific to the rotor size? Or do you need a new caliper bracket when you change rotor size?

I was reading about the Juicy 5s and somewhere I saw that you need to rebuild the calipers (ie change seals etc) yearly. However I coldn't find any support docs on the SRAM site to confirm this. I this true for all hydros? Thanks for all of the input.

you only need to change out the brackets for different rotor size. all calipers are the same as far as i know. As for rebuilding the calipers each year, i have never heard that before. I have been running shimano for the past couple of years and had no problems to date. and the same with friends that run Avid.

A
 

jdog

Shop: Halter's Cycles
Shop Keep
The reality is that almost no one does any service to hydros until they start causing trouble.

We sell tons of bikes that come stock w/ Avids and in reality I am rarely doing any service to them. Simply put, they are tough.

I personally prefer Magura or Shimano simply because they run on Mineral Oil vs. DOT toxic oil.


J-
 

rlb

Well-Known Member
Can the Avids be run w/ mineral oil, or will it eat the seals? The DOT fluid was a concern for me since it eats paint (does mineral oil?). And if you blow a seal or puncture a hose on the trail you'll be leaving the fluid behind...
 

jdog

Shop: Halter's Cycles
Shop Keep
Can the Avids be run w/ mineral oil, or will it eat the seals? The DOT fluid was a concern for me since it eats paint (does mineral oil?). And if you blow a seal or puncture a hose on the trail you'll be leaving the fluid behind...

Avids can only be run with DOT oil.

Dot will eat your paint, skin..etc

You could potentaily injest Mineral oil with little harm.

Shimano's new XT's are super btw.. I have Magura on ALL my bikes but I was impressed with the 09' XT's.
 

ChrisG

Unapologetic Lifer for Rock and Roll
Regarding modulation: I experimented with a 180 on the front of a rigid SS with a Salsa steel fork. While the braking power was tremendous, the fork chattered like crazy under heavy braking and the modulation was pretty much on/off. Running a 160 gave me a much more progressive lever feel, and at 145 lbs., I don't miss the power of the 180 very much.
 

Fogerson

Former Resident Nerd
Regarding modulation: I experimented with a 180 on the front of a rigid SS with a Salsa steel fork. While the braking power was tremendous, the fork chattered like crazy under heavy braking and the modulation was pretty much on/off. Running a 160 gave me a much more progressive lever feel, and at 145 lbs., I don't miss the power of the 180 very much.

No doubt at 145 lbs 180 would be too much rotor. It seems "just right" for me and I got a solid 50 lbs on ya'.
 

Ian F

Well-Known Member
I agree with running a 160 rotor... Unless you're doing lift-serve runs, there is no need for awhile larger and they're more vulnerable to rock damage. Even in the DH world, there is a trend towards running smaller rotors in the rear (for while athere 8" F & R was the norm). Second, many fork makers have a "max rotor size" spec for forks since larger rotors put a lot of stress on the drop outs.

I run Hayes and have to admit that I've done basically nothing to them since 2002. I have a can a ATE Super Blue waiting for a fluid change, but I haven't gotten around to it... :eek:
 
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