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Disc Rotor Advice - Locking Power


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Promise this is going to be my last topic for a while :P

Some time ago, I read on this forum that some rotors give more bite and locking power. Can't get my head over why this might be, after all the brake pads are pretty solid so the shape shouldn't matter. Anyway if they really do differ in performance, I'd be very grateful if those of you who have some experience with various rotors could tell me which one of these shapes would give the most locking power. They'll be used with 8" BB7s.

I've narrowed my choices down to these four:

1.Accent SL

1312_1.jpg

2.Accent

53010236.jpg

3.Hayes

tarcza%20hayes%20203%20mm.jpg

4.Avid

8890.jpg

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My thoughts on it, don't think it's right but...

It's like xl monty pads and the short ones, they both work equally well (probably) because what the long lacks in concentration of pressure, they grab it back with more surface area and vice versa.

Same with disc, small surface area = large pressure on one bit, and vice versa.

I think that's a fairly good explanation of it, nice and concise, but i think i remember a respectable forum member, think it was either Tomm, or Janson rings a bell, telling me i was wrong.

If that was infact a shit explanation, do tell and i'll try write a better one.

Edited by Fat Pants
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Promise this is going to be my last topic for a while :P

Some time ago, I read on this forum that some rotors give more bite and locking power. Can't get my head over why this might be, after all the brake pads are pretty solid so the shape shouldn't matter. Anyway if they really do differ in performance, I'd be very grateful if those of you who have some experience with various rotors could tell me which one of these shapes would give the most locking power. They'll be used with 8" BB7s.

I've narrowed my choices down to these four:

1.Accent SL

1312_1.jpg

2.Accent

53010236.jpg

3.Hayes

tarcza%20hayes%20203%20mm.jpg

4.Avid

8890.jpg

INUR buy all of them, road test them and gives us a review, hehe, i was thinking of getting a accent rotor, but i havent dinged my disc yet so will possibly purchase one in the future,

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I know exactly what you mean, from my experience short pads actually work better (cousts for that matter).

With disc brakes however, if you take a rotor with very little braking surface like #1, you have to establish if the extra pressure exerted on the rotor will make up for there being less friction between the rotor and brake pads. Also, if the brake pads aren't dead solid (which they probably are), the wavy shape of the rotor would allow for more locking power.

Read about rotors making a difference in a post in which the author was writing about Leeson rotors and that they have extremely good bite. Thought it was Rich Pearson or the "Don't you just hate it when" chap, not sure though.

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Hope saw rotor is supposed to work really well with an Avid

you don't need lots of heat dispersion with trials brakes so the more material on the disc - the greater braking surface.

I have tried some avid one and the do lock well but tend to snap i think after seeing some pictures.

So go on - the more meat the better braking, but can cause over heating on heavy/constant braking

- the larger surface area the better heat dispersion, but less braking power/surface to pad contact

Rob

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With disc brakes however, if you take a rotor with very little braking surface like #1, you have to establish if the extra pressure exerted on the rotor will make up for there being less friction between the rotor and brake pads. Also, if the brake pads aren't dead solid (which they probably are), the wavy shape of the rotor would allow for more locking power.

Probably just cancels each other out. Or makes very little difference.

It's a bit like pushing or pulling a trolley (or something similar), either way it moves, just moving it in different ways.

OOO, better comparison (i think) soft pads on a smooth rim or hard pads on a ground rim, all the same!

Edited by Fat Pants
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I'm not sure about the rotor's power entirely, but the best avids i've ever used were running rotor number 4. I also know that rotors like number 1 have a large variation in pressure which results in the brake pulsating when you apply it. It makes the front end judder and sometimes the brake works instantly while other times it has a bit of a delay in the bite. A rotor like the hayes one doesn't have the same problem.

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I used to have those for a while.

And they are total crap.

41736575.jpg

Later I got your #1. You call them Accent SL. In the Russian bikeshops they are sold as Ashima. Togethger with Koolstop pads they work great on my martas.

It's just such a massive difference I got from the braking..

But surely, the next step is Hope Mono Trial 2007.

1312_1.jpg

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As I have posted before, friction is not a function of area or pressure, but a function of the force applied and the coefficient of friction between the two materials.

I have found the Avid Cleansweep rotors to work really well. They used to be the standard for BB7 I think, not the roundagon ones.

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As i understand it, more surface area the greater the braking, i cant quite rememeber the forumla to prove that. But the more holes ect wehich gives less surface area give greater heat dispertion, for trials that doesnt matter to much. Also people have said that with using gothic rotars ect that arnt just circular there brake judders. I would say just go with a simple rotar design like the normal hope rotar that has a decent amount of surface area and holes to get rid of the heat. I do use the avid ones meself one of the orignal ones not the wavey ones and have never had problems with it, some people have snapped them but i use a 203 one and have give it a couple of bangs and its been fine and it must be a year old now.

Edited by basher
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i didnt bother reading all the replys so sorry if someone has already said this, but i thought the more holes the better and the larger they are the better, as i thought the pads gripped around it, im sure i read that in another topic about rotors a little while back,and obviously theres more heat reduction with more/bigger holes

Edited by braintreetrials
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I used to have those for a while.

And they are total crap.

Funny you should say that, had an identical rotor and it was utterly useless.

Janson - indeed the cleansweep rotors are great, my friend has a 180mm one which is just as powerful as my 203mm Hayes (on the same brake of course). The only issue is the price. For the price of one CS rotor I can buy 4 Accents <_<

So to sum up, I should go for the rotor with the greatest surface area, ideally something like the old GustavM rotors or Plazmatics which didn't have any holes?

edit: do you know where one can get hold of such rotors (got to be made of steel)?

Edited by Inur
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No holes = bad, the pads glaze quickly.

Big holes = more bite, less holes = more lock (in my experience)

Try a Hope Bubble rotor if you can get one, as used on the old Mini brakes.

I also think there may be a difference between different materials, cheapo rotors generally aren't all that good...

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Thanks for making that clear Sir Tart. Will probably stick with the Cleansweeps. Any idea about how much an 8" might weigh?

Alrightt ,

Just ordered number 2 today so il let you know what its like when i get it (Y)

They're alright, used them for quite a while. One thing I noticed was that they were really durable and very heavy. While it took me 2 months to completely destroy a Hope Trials rotor, this one lasted me 7 months.

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