[WTGPhoben]

For those who have run disc brakes in the past (all of you):

Can someone describe the difference in feel (lever feel, modulation, etc...) between a bike with a larger rotor in the front vs. matched size rotors. Which do you like better and why?

I already know all the physics - you don't need as big a rotor in the back, etc. etc... I'm looking for some nice qualitative impressions.

...and Please be a little more thoughtful than "I have XXX on my bike, and it's great".

Thanks!

(fyi, I'm looking at magura marta matched 180mm, or mismatched 160/180mm)

 

[OGRipper]

For me it's about friction, and the different amount of effort needed to slow down. More rotor means more friction per wheel revolution, which translates to less effort to brake. In my experience the lever feel is similar but you have better control with less effort.

 

[Toshi]

i've always been a fan of the front brake, as i read at a tender, impressionable age that skidding ruins trails.

thus i've never really minded having a 6" rotor out back, except on the dh rig: this is an admittedly bad example, but the 6" avid mechanical disc i ran for a while on the back of my canfield made me conscious of it, and that's not a good thing. the 6" hayes that i've also run at various points felt pretty similar, except maybe with less "give" in the lever.

so to actually answer your questions instead of giving random examples, i'd say that i've had no complaints with lever feel or modulation running either matched or mismatched avid or hayes discs, except on my dh rig where 8" all around was clearly superior imo.

 

[WTGPhoben]

so to actually answer your questions instead of giving random examples, i'd say that i've had no complaints with lever feel or modulation running either matched or mismatched avid or hayes discs, except on my dh rig where 8" all around was clearly superior imo.

so would you pay $30, and some number of grams EXTRA to match the rotors on an XC/vlight-duty freeride bike, or would you just run 180 up front and 160 in back?

 

[Toshi]

on such a bike i'd save the money and the weight and run mismatched rotors.

 

[sanjuro]

I already know all the physics - you don't need as big a rotor in the back, etc. etc... I'm looking for some nice qualitative impressions.

You are asking a very subjective question based on a lot of factors: Brakes, riding style, conditions, types of downhills, etc.

The only qualitative question you can really ask is weight vs braking power: do you need more braking power vs increased weight?

 

[WTGPhoben]

You are asking a very subjective question based on a lot of factors: Brakes, riding style, conditions, types of downhills, etc.

The only qualitative question you can really ask is weight vs braking power: do you need more braking power vs increased weight?

yes, I am deliberately asking a subjective question. I'm basically asking, does it feel strange to have two brakes that have different stopping powers (by about 10% says magura). Obviously, you're not going to NEED as much stopping power in the rear because all your weight shifts forward while braking, so the questions are more: does it feel "strange" (subjectively to you) to have one brake do X stopping for a given lever force and another do 1.1*X, and do you perceive there being any significant positive or negative effect to the fact that the rear brake is less powerful?

These may seem elementary questions, but I've logged about 5min lifetime total on bikes with discs, so I am merely looking for people's first-hand experience. It's ok that there are a lot of factors involved. I would hope that people would describe how some of these factors were involved in their impressions: "When I ride steep loose downhills I find that..."

 

[shiggy]

yes, I am deliberately asking a subjective question. I'm basically asking, does it feel strange to have two brakes that have different stopping powers (by about 10% says magura). Obviously, you're not going to NEED as much stopping power in the rear because all your weight shifts forward while braking, so the questions are more: does it feel "strange" (subjectively to you) to have one brake do X stopping for a given lever force and another do 1.1*X, and do you perceive there being any significant positive or negative effect to the fact that the rear brake is less powerful?

These may seem elementary questions, but I've logged about 5min lifetime total on bikes with discs, so I am merely looking for people's first-hand experience. It's ok that there are a lot of factors involved. I would hope that people would describe how some of these factors were involved in their impressions: "When I ride steep loose downhills I find that..."

No, it does not feel "strange" to me. In extreme conditions a larger front rotor means I am using about the same light effort (which is one of the reasons I use discs in the first place) on both levers.

 

[sanjuro]

yes, I am deliberately asking a subjective question. I'm basically asking, does it feel strange to have two brakes that have different stopping powers (by about 10% says magura). Obviously, you're not going to NEED as much stopping power in the rear because all your weight shifts forward while braking, so the questions are more: does it feel "strange" (subjectively to you) to have one brake do X stopping for a given lever force and another do 1.1*X, and do you perceive there being any significant positive or negative effect to the fact that the rear brake is less powerful?

These may seem elementary questions, but I've logged about 5min lifetime total on bikes with discs, so I am merely looking for people's first-hand experience. It's ok that there are a lot of factors involved. I would hope that people would describe how some of these factors were involved in their impressions: "When I ride steep loose downhills I find that..."

A lot of it has to do with riding styles. For example, I tend to drag the rear brake a bit, but just feather the front (which sounds like the opposite of Toshi).

Some of it is also riding locations. In Northern California, with alot of long straightaways, people tend to stay on the brakes, which larger rotors help with heat dissapation as well as modulation. From the places I rode in the East Coast, I found that most downhills were shorter and involved a bit turning, and I would often lock up my brakes, and having one larger rotor would probably not have helped me.

I plan on getting a 6-7 inch trail bike next year, and I am putting a 7 inch front rotor on that bike. I can't say that I have any experience with different sized front and rear rotors, but I will be doing a lot of long runs and more braking power without a major increase in weight is what I am shooting for.

 

[PaulE]

I'd only go for the larger rear rotor if you intend on doing long continually steep DH sections, where overheating is going to be a problem. Other than that, the extra power of a larger rear rotor is pretty much pointless, even with a 140mm rotor you can pretty much always lock the rear wheel.

[please realise I'm not recomending 140mm rear rotors - they overheat chronically on anything worth calling a descent]

 

[OGRipper]

No it doesn't feel strange to me. Front and rear brakes do different things and require different technique, regardless of rotor size, so either way you need to feel each out separately. More power with less effort means more control and less fatigue. I would not spend more to get a smaller rotor. The weight difference is minimal IMO.

 

[trailblazer]

i am with ogripper
weights of discs and tyres should never come into play. They are the backbone of your ride.
The smaller rotors will wear out the discs and they may bend if you do alot of DH runs...and doing any DH needs a 160 rear and a 180 front. I do DH with 160's and my front brake gets hot and the pads wear quick.
As far as fatigue goes....i notice it on my bb7s near the end of a ride and not on my XTR hydros.

 

[Quo Fan]

I have a bike with 6" rotors and a bike with 8" rotors. I have ridden the same trails with both bikes. I use less lever pressure with the larger rotors than with the smaller rotors, even though the bike with the larger rotors is heavier. In my experience, the larger rotors have more stopping power.

My braking style is to tap the rear brake to scrub a little speed when entering or riding through a turn, and the front for stopping and speed control while descending.

I hope this helps.

 

[zebrahum]

I've had two bikes with mismatched hayes hydros, and have never wished for more rear braking power. It doesn't feel weird, and I'm with Quo Fan; I find myself doing a few rear brake taps before some tech sections and in those situations, the smaller rear rotor is a benefit. You don't skid out from over braking, but your front brake is able to stop you fast.

 

[Sandwich]

I'm with pretty much everybody here. I have hope dh04s on my brooklyn, with 8/7" rotors, and 24" wheels. I ride a lot of steep rocky trails, and I don't find having a 7" in the rear to be a problem. Braking power is constant, and fade hasn't been too big of a deal except on super gnarly trails, and that may have more to do with my pads. My bike is about 50lbs, so weight isn't that much of an issue, but cost is- I have 3 7" rotors and no more 8". I don't think you'll notice an issue. Also, I have plenty of power to lock up the rear, and good modulation when it gets steep or fast.

I don't know if I'd really want another 8" unless I were doing super fast runs. Too much power and I'd be locking up all the time.

 

[skatetokil]

I have a 203 front/160 rear, both avid mechs.

I actually think the mismatch makes the levers feel more even since you reach the break loose point with about the same pull effort.

 

[trailblazer]

also since 80% braking is done by the front you don't need a large rear rotor.

I think it's all ok as long as they are all hydro or mech. Mixing hydro/mech feels wierd.