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  1. #1
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    brake questions

    Im working on my first build (Sultan with xx) and was wondering about brakes. Why are there different rotor sizes and what difference does it make and what size should I go for?
    Im not sure if this matters but the type of riding Ill be doing is local trails nothing crazy and probably a little street riding.

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    Simply put, a larger rotor provides greater leverage against the forces the brakes are trying to defeat. So... it is all relative, if you are a small guy riding mostly CC and road (relatively low forces applied), then a 6" rotor should me fine. If you are a bigger guy or wind up riding more aggressive stuff (greater forces being applied) a larger rotor might be in order. All that being said the power of you actual brake system is another variable, though if you go with the XX I am sure you will have plenty of grab. I am 165lbs and ride primarily trails with some pretty technical down hill stuff and I run 6" rotors in the rear and 7" rotors in the front. The front gives me plenty of power and I save a little weight in the rear. I hope this wasn't too convoluted.

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    thanks!

    That makes a lot of sense. I checked my current ride and they are 160 front and rear and I would would imagine that would be fine for my build because I dont have any issues with those at all and considering the type of riding I do. But Im curious why do you ride a larger rotor in the front and not in the rear?

  4. #4
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    Well its simple physics really your weight is going forward, so when you are trying to stop there is more of a force put on the front of the bike than the back, so it takes more force to stop the front wheel from spinning. I only weigh 120 lbs and I am running 160 rear 180 front

    but if what you have stops you fine already there is no reason why it wont stop you on the sultan.
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  5. #5
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    Quote Originally Posted by puckdaddy
    Im working on my first build (Sultan with xx) and was wondering about brakes. Why are there different rotor sizes and what difference does it make and what size should I go for?
    Im not sure if this matters but the type of riding Ill be doing is local trails nothing crazy and probably a little street riding.
    Sorry if this sounds harsh, but why on Earth would someone drop the $ on XX when they are not even in tune enough with bike components to know what rotor size does?

  6. #6
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    Quote Originally Posted by kapusta
    Sorry if this sounds harsh, but why on Earth would someone drop the $ on XX when they are not even in tune enough with bike components to know what rotor size does?
    I honestly was thinking the same thing, Sultan+XX buildup... seems like a serious project ($$$$) for someone who doesnt know the basics of building a bike.
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    I agree, but man you guys are harsh.....but maybe the OP is a brain-surgeon and has mega-bucks to spend on his first build ????

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    I ???
    Last edited by osmarandsara; 11-29-2009 at 09:10 PM.

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    no worries

    Quote Originally Posted by kapusta
    Sorry if this sounds harsh, but why on Earth would someone drop the $ on XX when they are not even in tune enough with bike components to know what rotor size does?
    The truth is I have more money than sense. I have no wife or kids and make good money. Also I wanted to keep the weight around 27 lbs. I also compared other components but in the end it only works out to be an extra 1k. Im doing this over time so its really not that bad. Im always searching for good deals. Right now all I have is the frame, fork, wheels, and crankset and have already saved $1200 off retail, not bad right?

  10. #10
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    Better he spend $600 on disc brakes and actually ride the bike than 2K on a Big screen TV and sit and do nothing. But Im sure he already has the TV

  11. #11
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    Quote Originally Posted by puckdaddy
    The truth is I have more money than sense. I have no wife or kids and make good money. Also I wanted to keep the weight around 27 lbs. I also compared other components but in the end it only works out to be an extra 1k. Im doing this over time so its really not that bad. Im always searching for good deals. Right now all I have is the frame, fork, wheels, and crankset and have already saved $1200 off retail, not bad right?
    But is 2x10 even what you want?

  12. #12
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    Quote Originally Posted by puckdaddy
    The truth is I have more money than sense.
    where do you live? - wanna be friends?
    Honestly... ahh I give up

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    Quote Originally Posted by puckdaddy
    Im working on my first build (Sultan with xx) and was wondering about brakes. Why are there different rotor sizes and what difference does it make and what size should I go for?
    Im not sure if this matters but the type of riding Ill be doing is local trails nothing crazy and probably a little street riding.

    In addition to the leverage thing, the bigger rotor provides more heat transfer so the brake stays a bit cooler...

    If you regularly cook your brakes (you will have brake fade and smoking clinking rotors) then you should consider a bigger rotor...

    I cook my 6 inch rotors, front and rear...so I will go to a 203 mm rotor up front, and leave the 6 inch on the rear...When things get hot I will have to use the front a little more...

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    Quote Originally Posted by kapusta
    But is 2x10 even what you want?
    Sure, I mean thats whats on my road bike and its not terribly hilly around here.

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    thanks!

    Quote Originally Posted by jeffscott
    In addition to the leverage thing, the bigger rotor provides more heat transfer so the brake stays a bit cooler...

    If you regularly cook your brakes (you will have brake fade and smoking clinking rotors) then you should consider a bigger rotor...

    I cook my 6 inch rotors, front and rear...so I will go to a 203 mm rotor up front, and leave the 6 inch on the rear...When things get hot I will have to use the front a little more...
    Thanks, thats good to know

  16. #16
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    Quote Originally Posted by puckdaddy
    Sure, I mean thats whats on my road bike and its not terribly hilly around here.
    You also have rim brakes and drop bars on your road bike.

    I'm just saying that xx was developed with competitive xc racers in mind. That does not mean it is necessarily BETTER for most riders. You say it is only $1K extra, but do you even know what you are getting for that and if it serves YOU better?

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    Be aware of clearance with your rack. I was running 185's with juicy 5's no problem, but when I went to 180 XT's the rotor is thicker and it hit the bike rack making it really hard to get the bike off the car. If I had gone with 160's there would have been no problem.

    So why did I go 180? Well I was replacing 185's. How could I go 160 again? (I know, lame).

    Personally I like the xx group. It's not much different then getting a 34T cassette on a 2x9. You get that higher climbing gear without having to drop down to the smaller ring upfront.

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    Quote Originally Posted by kapusta
    You also have rim brakes and drop bars on your road bike.

    I'm just saying that xx was developed with competitive xc racers in mind. That does not mean it is necessarily BETTER for most riders. You say it is only $1K extra, but do you even know what you are getting for that and if it serves YOU better?
    I think you are giving this product too much credit. So if this was designed for racing then it should perform nicely for what I want it for. Are you suggesting that I can't handle it that it's too much for me and that a cheaper drive system would be better. Please be specific as to why I shouldn't have it

  19. #19
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    Quote Originally Posted by puckdaddy
    I think you are giving this product too much credit. So if this was designed for racing then it should perform nicely for what I want it for. Are you suggesting that I can't handle it that it's too much for me and that a cheaper drive system would be better. Please be specific as to why I shouldn't have it
    I'm not saying you should not have it, but there are some things about it that make it desirable for a competative xc racer but not a trail rider, even a very strong and experienced one. They are at least things to think about. I for one would choose an X.0 group given the choice. Go look up threads on 10 speed drivetrains and you will see why some people have no interest in them.

    Have you decided what chainring and cassette option you want?

    Are you a competitive racer? Forgive me if I misunderstood, I though you were not. What kind of riding do you do?

  20. #20
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    let him get it!!!
    XX will be lighter and perform better than X.9 for instance.
    the sized rotors you should get depend on your weight and type of riding.
    i weigh 155 and ride flat XC with only minor downhill sections. i use 160 on F/R.
    its not like the Sid/Reba where the SID has some quality problems and won't last as long as the Reba.
    RH SL Pro

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    Quote Originally Posted by kapusta
    I'm not saying you should not have it, but there are some things about it that make it desirable for a competative xc racer but not a trail rider, even a very strong and experienced one. They are at least things to think about. I for one would choose an X.0 group given the choice. Go look up threads on 10 speed drivetrains and you will see why some people have no interest in them.

    Have you decided what chainring and cassette option you want?

    Are you a competitive racer? Forgive me if I misunderstood, I though you were not. What kind of riding do you do?
    Im not a racer just a 10-20 mile trail/singletrack rider. I havent seen too many negative opinions about a ten speed drivetrain but Ill look into it. Ive already purchased the crankset and its a 28/42 and probably just go with the 10 speed cassette that goes with the group. Is it possible to run a 9 speed in its place?

  22. #22
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    If you're going to run 2x? anyway, no reason not to go for the 10spd if price is no issue.

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    Quote Originally Posted by puckdaddy
    Im not a racer just a 10-20 mile trail/singletrack rider. I havent seen too many negative opinions about a ten speed drivetrain but Ill look into it. Ive already purchased the crankset and its a 28/42 and probably just go with the 10 speed cassette that goes with the group. Is it possible to run a 9 speed in its place?
    Nevermind my second guessing, you already have it, so just enjoy it!

    I'm sure it will be a very nice setup and you will be very happy with it!

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    no worries

    Quote Originally Posted by kapusta
    Nevermind my second guessing, you already have it, so just enjoy it!

    I'm sure it will be a very nice setup and you will be very happy with it!
    I did check some of the old forum posts and wow its a heated debate, the 10 speed drive. Worst case scenario I just make an expensive mistake right, but I think itll be fine. Thanks for all the help, Im definitely gonna have more questions as I go, this is a learning experience after all.

  25. #25
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    That is the thing about being new, you know you want the best gear you can possibly get. you hear that something is revolutionary and new and is going to rock the way we ride bike, and you go ahead and get it, not realizing that it might not be for you.

    I am sure you will love it really, I have demoed it, I ride AM-FR and I was very impressed by the shifting, the price point to me is a little nuts, and it just... it wasnt for me. People on these forums will ALWAYS help, even if they are a bit harsh at getting their points across sometimes, dont be afraid to ask questions before spending hard earned cash. Even if you do have a influx of cash right now, its a little silly to just blow it unless of course you are buying american, in which case go for it our economy could use the boost
    Last edited by ThePinkBarron; 12-01-2009 at 09:31 AM.
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    Have you already maxed out your IRA contributions this year? If not im sure most here would recommend you work on that before you spend it on a bike.

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    Quote Originally Posted by ThePinkBarron
    . unless of course you are buying american, in which case go for it our economy could use the boost
    Its funny you say that. It is my goal to keep it American as possible. I know all the components are made overseas, but Ill only by from American distributors not to mention the frame is American. But what I want people to realize is is that the guy who buys a Rolls Royce probably doesnt know anything about brakes and remember when was the last time you saw a mechanic driving a sports car. Take care!

  28. #28
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    Quote Originally Posted by puckdaddy
    Its funny you say that. It is my goal to keep it American as possible. I know all the components are made overseas, but Ill only by from American distributors not to mention the frame is American. But what I want people to realize is is that the guy who buys a Rolls Royce probably doesnt know anything about brakes and remember when was the last time you saw a mechanic driving a sports car. Take care!
    Well, keep in mind that one buys a RR largely as a status symbol (especially if they don't know why it is any better for them than something costing half as much). It says "I am well off", not "I am a skilled driver". It is almost all about show.

    A beginner rider a Turner with an xx build says "poser".

    While a RR may improve your image among its target audience , this bike will likely lower it. Not that this should be why you buy this bike, but since you brought up something like a RR as a comparison, it is worth mentioning.

    I am curious why you went with the 28/40 cranks. Are you sure you want a 28t ring as your lowest option on a 5" FS 29er? You say it is not hilly where you are, but might you not go somewhere else?. Maybe you are stronger rider than myself, but I would find that a real limitation for that bike. it would be different were it a hardtail or short travel FS (which are a lot better for standing and hammering than a 5" FS) or a 26" bike (which are basically a gear lower for a given cog/ring combo), but honestly that just seems like an odd choice for that bike.

  29. #29
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    Hi all ! It's his money , if he wants XX I say go for it . ( of course i'm the guy who just built up 2 IF bikes.....why ? cause I can )

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    Quote Originally Posted by kapusta
    Well, keep in mind that one buys a RR largely as a status symbol (especially if they don't know why it is any better for them than something costing half as much). It says "I am well off", not "I am a skilled driver". It is almost all about show.

    A beginner rider a Turner with an xx build says "poser".

    While a RR may improve your image among its target audience , this bike will likely lower it. Not that this should be why you buy this bike, but since you brought up something like a RR as a comparison, it is worth mentioning.

    I am curious why you went with the 28/40 cranks. Are you sure you want a 28t ring as your lowest option on a 5" FS 29er? You say it is not hilly where you are, but might you not go somewhere else?. Maybe you are stronger rider than myself, but I would find that a real limitation for that bike. it would be different were it a hardtail or short travel FS (which are a lot better for standing and hammering than a 5" FS) or a 26" bike (which are basically a gear lower for a given cog/ring combo), but honestly that just seems like an odd choice for that bike.
    So at what point do I not become a poser? Granted Ive only been riding 1 year, so is it 3 years, 5 years. I didnt buy this to impress anyone. Truth is I ride by myself because none of my friends ride. I appreciate your concern but I think Ill be able to handle it and if not Ill spend thousands more till I get it right. Take care

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    Quote Originally Posted by puckdaddy
    So at what point do I not become a poser? Granted Ive only been riding 1 year, so is it 3 years, 5 years. I didnt buy this to impress anyone. Truth is I ride by myself because none of my friends ride. I appreciate your concern but I think Ill be able to handle it and if not Ill spend thousands more till I get it right. Take care
    Right on Brother! buy what ever you want. ride what ever you want. If I had the money, hell yea I'd get a RR, and scudera for the weekend. You know what else? Most people can't tell the difference between 720p and 1080p, but I bet if the price wasn't different you'd buy the 1080.

    I don't need more then two pairs of underpants either, but I own several.

  32. #32
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    Quote Originally Posted by puckdaddy
    So at what point do I not become a poser? Granted Ive only been riding 1 year, so is it 3 years, 5 years. I didnt buy this to impress anyone. Truth is I ride by myself because none of my friends ride. I appreciate your concern but I think Ill be able to handle it and if not Ill spend thousands more till I get it right. Take care
    I'm sorry, but you brought up the RR analogy.

    It will be a sweet ride and you can be sure you won't want for something better.

  33. #33
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    Quote Originally Posted by mlepito

    I don't need more then two pairs of underpants either, but I own several.
    I own three.

  34. #34
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    . ( of course i'm the guy who just built up 2 IF bikes.....why ? cause I can )[/QUOTE]
    nice bikes, have you posted any pics?

  35. #35
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    Quote Originally Posted by BeaverTail
    Have you already maxed out your IRA contributions this year? If not im sure most here would recommend you work on that before you spend it on a bike.
    Good suggestion! The Roth IRA limit this year is $5000, use this over regular IRA if your financial situation allows. Contribute the max allowable to your IRA while you're young and let compounding interest increase your money. Before upgrading the bike, consider that $100 put into an IRA today at average return of 10% becomes $611.59 in 20 years and becomes $1586.39 in 30 years! I wish I learned this lesson when I was young.

    Let's now return to the original topic...

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