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Discussion Starter · #1 ·
well im about to order at least 1 set of AVID BB7 brake but dont know which size to get

my bike is a DB coil ex with a RS tora 318 u-turn fork

the bike has tektro IOX brakes on it now with 160mm rotors front and rear the rear does alright but the front just doesnt have the stopping power i would like

the fork manual says to use no larger than a 210mm rotor which would accomodate all BB7 rotor sizes

SO does the old saying Bigger is Better apply here? should i get 203mm rotors? or go in the middle and get 185mm? or stick with whats on it now and get 160mm?

i wanted to get 203 for the front and 185 for the rear

what are the advantages/disadvantages of larger rotors?

thanks for the help
 

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You included everything but the pertinent info.

How much do you way? What kind of riding are you doing?

Heavy? Fast? Long descents? All good reasons to upsize.

Pros of a bigger rotor is you'll stop more easily and manage heat build-up better.

Cons are you'll lose brake modulation, which could negatively affect your handling in slow-speed technical spots, and there's a minor weight increase and greater possibility of rotor damage.
 

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Discussion Starter · #3 ·
Speedub.Nate said:
You included everything but the pertinent info.

How much do you way? What kind of riding are you doing?

Heavy? Fast? Long descents? All good reasons to upsize.

Pros of a bigger rotor is you'll stop more easily and manage heat build-up better.

Cons are you'll lose brake modulation, which could negatively affect your handling in slow-speed technical spots, and there's a minor weight increase and greater possibility of rotor damage.
my weight is 150 lbs my bike weighs around 40lbs i ride old strip mine roads and pavement roads, but paved roads around here are pretty steep sometimes lol
and i ride as fast as i can, especially going down hill
 

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Old man on a bike
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I'd guess the 160 size would likely work well for you. You're going to get a much better brake itself, that alone is going to be your biggest improvement, especially if you use a lever that has a leverage adjustment (what levers are you going to be using?). I'd say 203 is definite overkill, maybe a 185.
 

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hondaman01 said:
my weight is 150 lbs my bike weighs around 40lbs i ride old strip mine roads and pavement roads, but paved roads around here are pretty steep sometimes lol
and i ride as fast as i can, especially going down hill
I was up close to 240 weight when I started using discs. 160 was good, but I constantly overheated it on a particularly long, steep and dusty descent from a local 2500' peak. I switched to 185 and that solved the heat problem, but I noticed the extra grabbiness in slow-speed stuff that I had to pick my way through.

At 150, I think you'll be very happy with 160 front and rear. Even potentially 140 rear.
 

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Discussion Starter · #6 ·
Speedub.Nate said:
I was up close to 240 weight when I started using discs. 160 was good, but I constantly overheated it on a particularly long, steep and dusty descent from a local 2500' peak. I switched to 185 and that solved the heat problem, but I noticed the extra grabbiness in slow-speed stuff that I had to pick my way through.

At 150, I think you'll be very happy with 160 front and rear. Even potentially 140 rear.
thanks for the advice, ill stick with 160 then

my levers are just the stock shimano v-brake levers that doubles as trigger shifters so they are not adjustable

but seriously thanks i tried searching but couldnt really find the answer i was looking for
 

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hondaman01 said:
thanks for the advice, ill stick with 160 then

my levers are just the stock shimano v-brake levers that doubles as trigger shifters so they are not adjustable

but seriously thanks i tried searching but couldnt really find the answer i was looking for
Doubt they came on that bike, but the upper level Shimanos do have the feature, off top of my head don't think below LX level, though. The leverage adjustment is nice to have, but in your case would be more $ to obtain.

The techdocs.shimano.com site can answer a lot of questions (the "EV" documents are drawings/part listings, the "SI" documents are installation/use instructions).
 

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Discussion Starter · #8 ·
Bikinfoolferlife said:
Doubt they came on that bike, but the upper level Shimanos do have the feature, off top of my head don't think below LX level, though. The leverage adjustment is nice to have, but in your case would be more $ to obtain.

The techdocs.shimano.com site can answer a lot of questions (the "EV" documents are drawings/part listings, the "SI" documents are installation/use instructions).
thanks for the website ill add that to my favorites

the bottom of my levers say ST-EF50 i think they are about the cheapest ones you can get with only barrel adjusters on them
 

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I see no reason to not go with the 203mm up front unless you care about the very small weight difference.

I had tektro 160mm on my bike stock and went with a 185 and then 203BB7s on the front. The larger rotor gave me BETTER modulation. A larger rotor requires less lever effort for the same braking force, more resistance to fade, and in my case better modulation. You may not require it but there are some advantages and the real question is why not? Brakes are one area you want overkill. I see too often people going with the minimum requirements and it makes no sense.
 

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Discussion Starter · #10 ·
BuickGN said:
I see no reason to not go with the 203mm up front unless you care about the very small weight difference.

I had tektro 160mm on my bike stock and went with a 185 and then 203BB7s on the front. The larger rotor gave me BETTER modulation. A larger rotor requires less lever effort for the same braking force, more resistance to fade, and in my case better modulation. You may not require it but there are some advantages and the real question is why not? Brakes are one area you want overkill. I see too often people going with the minimum requirements and it makes no sense.
yea that was my reasoning behind it, why not?
 

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hondaman01 said:
yea that was my reasoning behind it, why not?
Because overkill is overkill. Like Nate says, there can be uses for a larger diameter but it won't necessarily make the brake more effective. I tried 203s (and I'm 50 lbs heavier than the OP) and just found them overkill, too touchy for general riding (and my riding encompases plenty of descending). DH racing would be different.

PS like I said before, just the better brake can be a big difference...
 

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Discussion Starter · #12 ·
Bikinfoolferlife said:
Because overkill is overkill. Like Nate says, there can be uses for a larger diameter but it won't necessarily make the brake more effective. I tried 203s (and I'm 50 lbs heavier than the OP) and just found them overkill, too touchy for general riding (and my riding encompases plenty of descending). DH racing would be different.

PS like I said before, just the better brake can be a big difference...
yea i was worried that a 203 and the bb7 may be too much brake because i have nothing to compare these to just that i have to squeeze the piss outta them to get me to slow down
 

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hondaman01 said:
yea i was worried that a 203 and the bb7 may be too much brake because i have nothing to compare these to just that i have to squeeze the piss outta them to get me to slow down
If you want to split the difference, 185 might be a good compromise for you (I use 185 front, 160 rear on a few bikes, 160 fronts on others).
 

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hondaman01 said:
yea i was worried that a 203 and the bb7 may be too much brake because i have nothing to compare these to just that i have to squeeze the piss outta them to get me to slow down
I wouldn't go 203 unless you know you need it... but a 185 fr/160 rr is a very nice combo, imo. Not overkill. If you are swapping brakes anyway, might as well go up one size on the front rotor (assuming you are buying the rotors with the brakes). People don't often b!tch "my front brakes just stop me too well". It is only like a 16% difference in force from 160 to 185-not like a huge difference, but since you get more traction up front when braking, it just makes sense to me to offset with the bigger rotor, shows attention to detail. Motorcycles and dirtbikes have better brakes up front. If there was a big weight penalty, I'd say no, but the difference in weight from 160 to 185 is like nothing.
 

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Discussion Starter · #15 ·
Uncle Six Pack said:
I wouldn't go 203 unless you know you need it... but a 185 fr/160 rr is a very nice combo, imo. Not overkill. If you are swapping brakes anyway, might as well go up one size on the front rotor (assuming you are buying the rotors with the brakes). People don't often b!tch "my front brakes just stop me too well". It is only like a 16% difference in force from 160 to 185-not like a huge difference, but since you get more traction up front when braking, it just makes sense to me to offset with the bigger rotor, shows attention to detail. Motorcycles and dirtbikes have better brakes up front. If there was a big weight penalty, I'd say no, but the difference in weight from 160 to 185 is like nothing.
thats probably what i will do

if i dont like the 185 front i can always just put the 160 rotor and mount back on that i have now
 

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hondaman01 said:
thats probably what i will do

if i dont like the 185 front i can always just put the 160 rotor and mount back on that i have now
185 will be plenty but again there's no good reason not to go with the 203. I've never had a problem with the 203s being too touchy. You adjust and adapt to the new brakes and before long you don't notice how much easier the braking is until you ride a bike with the smaller brakes again. Mine have excellent modulation but if you do have issues with them being too touchy, the cure is $20 away with a set of speed dial levers to dial in more or less modulation.
 

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hondaman01 said:
thats probably what i will do

if i dont like the 185 front i can always just put the 160 rotor and mount back on that i have now
As long as the mounts are the same (not that familiar with the Tektro caliper/mount, though it appears they're the same), that's a good plan!
 

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Discussion Starter · #18 ·
Bikinfoolferlife said:
As long as the mounts are the same (not that familiar with the Tektro caliper/mount, though it appears they're the same), that's a good plan!
yea comparing pics they look tobe real close, close enough to where if i need to i can take them to work and machine whatever i need to make it work
 

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I like that plan, too. Good thinking.

You ever driven a car that's been sitting for a while, and has rusty, sticky brakes? Where if you're creeping in a parking lot you just tap the brake and the car lurches to an embarrassing stop? That's kind of what it's like to crawl through sticky terrain with an oversized rotor. With the BB7s, sure, you can "detune" the power to dial some of that "on/off" out, but then you're compromising your braking performance at higher speeds. That's where I'm coming from on my recommendation.

But since you've got the 160mm adapter and rotor, go for the 185. If you feel sufficiently motivated, try both sizes in a variety of conditions. Then you can come back and lend your first-hand experience to future discussions on the subject.
 

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Pick up a set of Avid Speed Dial 7 levers to compliment your BB7's. My bike came with Hayes MX 4 brakes plus Tektro levers and they were awful. I weigh 240 and on downhills the front brake would overheat and fail. I switched to BB7's with 160 rotors and haven't had a problem since. The Speed Dial 7 levers allowed me to adjust the amount of pull to the way I like it. You can pick up a pair cheap at Jenson right now.

http://www.jensonusa.com/store/product/BL306E01-Avid+Speed+Dial+7+Levers+08.aspx
 
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