[IthonEng]

Change of Topic

Now that i've got some valuable input on brake mounts, its time to move onto another - headset specification.

--------------------------------

Morning fellow Monkies!

I used to post on hear years back but drifted away for one reason or another. I thought i'd pop back and try and tap into the experienced folk here and have a good old fashioned technical discussion......on brake mounts. Exciting stuff!

So why brake mounts? Well after drifting away from the sport i'm getting back involved and would like a new bike. Problem is I don't want to be giving up my hard earned cash to any one of the companies already out there....i'd rather do it myself.

So to the question - Post mount or IS?

A few years back IS used to be pretty much standard, but now it seems post mount is having a bit of a resurgence.

I always used to favour Hope and IS, until I picked up a set of Hayes brakes and was impressed with the 'easier' set up of the caliper with the disc.

So what are your opinions on this? I guess some people aren't too bothered but if any of you have good technical reasons why one may be better than the other it would be good to hear your input.

Thanks in advance!

 

[Huck Banzai]

Most, or all, brakes are post mount these days; or at least have a post mount option. IS mounts are retreating and have all but been abandoned for forks.

I dont think there's any advantage to IS unless you like your brake setup to be challenging. The only dig I ever saw go at post mount is "What if you tear the threads out" - which is pretty unlikley outside of some power-ham-fisted wrenching.

eh?

 

[IthonEng]

Thanks for the input Huck. That is my thinking but wondered why it has taken so long to go this way.

The comment about stripping threads is valid but you are right, unless your extremely heavy handed then it shouldn't be an issue. Or have replaceable thread inserts. Thats a idea right there!

 

[SkullCrack]

The comment about stripping threads is valid but you are right, unless your extremely heavy handed then it shouldn't be an issue. Or have replaceable thread inserts. Thats a idea right there!

i really like Turner's rear post mounts:

 

[IthonEng]

Thats a neat idea. Can't help thinking its encouraging people to be heave handed. But from a customer satisfaction point of view its a nice touch - no angry customer complaining their 2k frame is threaded!

Any obvious/not so obvious disadvantages to Post mount?

 

[iRider]

Any obvious/not so obvious disadvantages to Post mount?

Manufacturers have to decide which size disc their customers want to run (PM160, PM180, PM200) to avoid adapters. However, if you wan to run a different size disc then the manufacturer thinks you should then you can only go bigger, not smaller. Annoying for lighter riders to not be able to ride a 160 mm disc on some enduro/AM frames that have PM180.

 

[IthonEng]

iRider thats a valid comment.

I suppose from a function point of view if you are designing an AM/Enduro frame then you can make the assumption that most people will probably ride a 140/160mm rotor. Even larger riders wont need to go bigger than 160. So you could design in for 140 and then there is the scope to increase to 160 (or higher in the rare occasion it might be needed). Again the same can be said for a DH frame. Most riders will probably run a 180/200mm rotor, so design accordingly.

If someone decides they want to run a 140mm brake on their V10 then somethings not quite right!

On this topic though, and I may be missing something here, but how is the above constraint different for IS mount? You can't go smaller than the minimum rotor size it is designed for.

 

[Huck Banzai]

On this topic though, and I may be missing something here, but how is the above constraint different for IS mount? You can't go smaller than the minimum rotor size it is designed for.

Arent the IS mounts standardized in location and you can use w/e adapter to go 140/160/180/200, whereas the posts set a minimum size, and you can only step up 1 size w/ adapter?

Lots of ?'s but I think fundamentally thats the main diff

I find it rare that anyone runs anything but a 200mm up front, bar a few light brake users, and those that want to appear more pro.. (like the moto lever swappers (not all of themm...) OH NO YOU DINT...), and most people run a 180 or 200 in the rear, so as far as building a DH frame as long as you have that option in the rear, most people will be happy (and still most will run the 200mm out back as well)

 

[IthonEng]

I wasnt aware that you can only increase by 1 size on post mount. That would go a long way to explain it.

As it turns out its a AM/Enduro frame i'm looking into so 140/160 is probably the way to go.

 

[iRider]

I wasnt aware that you can only increase by 1 size on post mount. That would go a long way to explain it.

You can go up by two sizes with PM, no problem. At least on forks. But a real problem seems to be to step up from PM180 to PM203 as most adaptors only cover PM160 to PM203.

@Huck Banzai: If you have real brakes and are not obese 180 mm front discs are a real possibility on not too steep or too long courses.

 

[marshalolson]

You can go up by two sizes with PM, no problem. At least on forks. But a real problem seems to be to step up from PM180 to PM203 as most adaptors only cover PM160 to PM203.
.

pm160->pm180 is same adapter as pm180->pm200

 

[IthonEng]

iRider - Thanks for the clarification on that. Theres also nothing to stop custom adapters should somebody want to go 180 - 203.

Any other disadvantages of PM? Or maybe, advantages of IS?

 

[iRider]

pm160->pm180 is same adapter as pm180->pm200

You are right, but I have seen a couple of cases where the caliper was placed weird (not perfectly aligned with the disc) when done this way. So I was under the impression it doesn't work always.

Edit: just realized that we are talking about two different things: 200 and 203 discs!
Maybe this was the reason it didn't work?

 

[samnation]

I think that as long as AM/XC bikes come with a 140mm PM mount with an adapter available to do everything up to 180/185mm rotors and DH bikes come 180 with the option to go to 185/200/203 there would be no complaints about not being able to run small enough rotors.

That's my thoughts on it all.

 

[IthonEng]

Samnation, im inclined to agree. Im now decided on post mount and will look more closer into rotor size as times goes on. But your right 140 upwards for AM seems the best solution.

Change of Topic

Now that i've got some valuable input on brake mounts, its time to move onto another - headset specification.

The same discussion applies but there are more options available:

Size
1 1/8 Top and Bottom
1 1/8 Top - 1.5 Bottom
1.5 Top & Bottom

Type
Zero Stack
Integrated
Conventional Press in Cups

Remember its for a AM/Enduro bike so can likely afford to go something lighter duty than DH. But still required to be durable.

So advantages/disadvantages of them. Problems you have had in the past or failures you've experienced?

 

[TWeerts]

http://www.parktool.com/blog/repair-help/headset-standards

check the chart near the bottom

 

[samnation]

If you are going to run a tapered fork or think you may run a tapered fork you will want to do a ZS44 top and ZS56 bottom, if the 1 1/8 is more your jive go ZS44 top and bottom.

 

[IthonEng]

Guys think you've gone a bit off topic. I appreciate the different types of headsets but wanted your opinions on preferred type, based on technical differences.

E.g - Zero Stack allows the front end to be lower - some people like, some not so bothered.

or 1.5 provides greater stiffness etc etc

 

[herbman]

Guys think you've gone a bit off topic. I appreciate the different types of headsets but wanted your opinions on preferred type, based on technical differences.

E.g - Zero Stack allows the front end to be lower - some people like, some not so bothered.

or 1.5 provides greater stiffness etc etc

i like the idea of a full 1.5 head tube, that way you can just buy the headset to match the steerer that you want to run.

 

[IthonEng]

Herbman, do you mean with full 1.5 you can choose to run either 1.5 or 1 1/8?

 

[herbman]

yup, full one point five. that way you can run a 1 1/8, 1.5 or any tapered combo inbetween, like 1.5 to 1 1/8 or giants 1 1/4 to 1.5 setup. just match the head set to the steerer and your away

 

[IthonEng]

Is 1.5 really required though? The reason for questioning its requirement is:

1 - Its an AM/Enduro bike - weight is important and its not developed to be sent over 50' gaps to hang up on or drop 20' to flat.

2 - For years, up untill recently, 1 1/8 has been sufficient. Ive never had a headtube failure on any bike racing DH and don't personally know of anyone who has. Not to say it doesnt happen though. But I think frame design can go a long way to eleviate the problem.

Im not interested in keeping up with the latest fashion, just developing something that is fit for purpose. So to me the 1.5 craze seems a little unnecesary.

Maybe I am wrong?

Also zero stack or conventional press in cups? I like zero stack - lower weight, lower/more comapct front end.

 

[Dogboy]

I prefer the ZS44/ZS56 headtube.

 

[Optimax150]

I would go for a full 1.5 headtube for more versatility. As for as break mounts there is no difference, just one extra piece for IS mounts, or for maybe for PM depending on size.
Maybe a little off topic, but your really overthinking things here. If you really don't know the standards search over the Internet, a bunch of info for you to catch up on. I can only imagine your next inquiry about suspension, breaks, cranksets, handle bars which in its own could be a monster for you.
Just my .02, there is plenty of info out there for you to find and catch up on the times.

 

[IthonEng]

On the top of low stack height there is the option for zerostack/integral or integrated.

I like integrated, again lowering weight over a standard integral/zero stack. But I cant help thinking that if there was damage to the bearing surface thats integrated into the frame, its not easily, if at all, fixable.

No one wants to replace their frame because the bearing surface was damaged. Thoughts on this?

 

[IthonEng]

Optimax, its not a question of 'knowing' the standards.

Its a technical discussion on pros and cons of the standards. Hence why trying to keep it on that track.

Essentially trying to get peoples input. As an individual you cant have tried, at least not for long enough, all the options to know the pros/cons. Collaboration helps everyone

 

[Sandwich]

Is 1.5 really required though? The reason for questioning its requirement is:

1 - Its an AM/Enduro bike - weight is important and its not developed to be sent over 50' gaps to hang up on or drop 20' to flat.

2 - For years, up untill recently, 1 1/8 has been sufficient. Ive never had a headtube failure on any bike racing DH and don't personally know of anyone who has. Not to say it doesnt happen though. But I think frame design can go a long way to eleviate the problem.

Im not interested in keeping up with the latest fashion, just developing something that is fit for purpose. So to me the 1.5 craze seems a little unnecesary.

Maybe I am wrong?

Also zero stack or conventional press in cups? I like zero stack - lower weight, lower/more comapct front end.

I cannot see any logic behind not going for a full 1.5" headtube, unless you have a steel frame. It gives you so many options. You can run reducer cups and have the equivalent of a zero stack (zs44) headset, or you can run a tapered headset with ZS on top, or you can run full 1.5, or you can run an extended cup
reducer headset, or you can run reducer cups and regular cups on top. The only thing it really can't do, I think, is a tapered zero stack top and bottom setup. Seems like most people are moving in that direction until the next standard is released, but I think most people would probably be ok with 5mm of cup sticking down from the bottom so they have the option of running any fork ever. 1.5 also allows you to really easily mess with geometry, with angled headsets.

Otherwise, I'd go with zs44/zs56 as you get most of the benefits.

 

[IthonEng]

Sandwich, I do see where you are coming from.

1.5 top & bottom does offer a whole lot of versability. I guess its not always a case of what is best, but where the trend is going.

 

[Optimax150]

Optimax, its not a question of 'knowing' the standards.

Its a technical discussion on pros and cons of the standards. Hence why trying to keep it on that track.

Essentially trying to get peoples input. As an individual you cant have tried, at least not for long enough, all the options to know the pros/cons. Collaboration helps everyone

For you knowing the standards will let you know what you want or looking for. If you don't know the standards you don't know what your looking for. Yes collaboration helps everybody but the person asking needs some sort of knowledge. If you don't know than just ask "what's up with nowadays headsets? Or break mounts?". Honestly I think if you would've done you research over the Internet you would have found your answers, or at least had more specific questions. Next your going ask the difference between a two pot and a four pot break caliper, sintered and organic break pads, a short cage or medium cage or even what's different about DH and FR frames?

 

[IthonEng]

Optimax - Sorry you've lost me. Im not here for an internet arguement or to impress you with my knowledge of the standards.

If you've got nothing useful to say, dont say it at all!

 

[kickstand]

@Huck Banzai: If you have real brakes and are not obese 180 mm front discs are a real possibility on not too steep or too long courses.

What's the advantage of this?

I can't see any sort of logic in wanting smaller rotors, I don't see a major weight savings, l don't see a major clearance advantage, etc....

I'd rather have larger rotors that take less energy to stop with, then having to squeeze harder with smaller rotors....every little bit of energy I can save in my grip means more runs in a day for me.

Am I missing some sort of logic that makes smaller rotors better?

 

[Optimax150]

Optimax - Sorry you've lost me. Im not here for an internet arguement or to impress you with my knowledge of the standards.

If you've got nothing useful to say, dont say it at all!

Sorry. Didn't mean for it to be a arguement or test of knowledge.
All I was trying to say is I think a lot of info could be found on the internet if you searched for it. This site search option and also, sorry to say but pinkbike also have a lot of info on it just need to sort the BS.

 

[Sandwich]

Sandwich, I do see where you are coming from.

1.5 top & bottom does offer a whole lot of versability. I guess its not always a case of what is best, but where the trend is going.

It's not always where the trend is going, but with bikes it's where is the trend going to go next. As if the 1.125" standard that's been around since 1996 isn't good enough, or that the 1.5" nor tapered 1.5 to 1.125" steerers corrected its shortcomings, giant has decided we need another standard in the format of 1.25", almost specifically to screw over the people who have collected stems in a variety of sizes for the past 15 years, or the people who jumped on the 1.5 bandwagon early.

With a larger diameter headtube, you're ahead of the curve, and anytime somebody invents another "standard", you can adapt it when they use their incredible market share to change something nobody wanted changed. Much like the 20mm axle, which is just fine and good for 99% percent of the people out there, Fox and whomever else came up with the 15mm axle, which uses a narrower profile, specifically to deny people who already own 20mm hubs the ability to easily convert (although many hubs are convertible).

I think anybody picking out a bike would do well to choose parts that are adaptable to market movements, like the 1.5" HT, replaceable dropouts, and convertible hubs.

That's just me though, there are plenty of apologists who will defend every "standard" that gets crapped out.

 

[IthonEng]

No love lost Optimax. I may be misinterpreting my own thread here (if thats possible) buteach standard has its pros & cons. I have done lots of reading up on them but you can get too ingrained in the in depth technical reasons for the different options.

By posting this thread you can get useful info from riders who use the equipment day in day out. A classic example is Huck/Skullcrack bringing up that some folk may strip their post mount threads. Not really a performance issue as such, just real rider usage/feedback on a small possible (design dependant) disadvantage.

Kickstand - Not wanting to drag my thread off topic but lighter guys could find the bike locks up too quickly with larger rotors. Its harder to moderate, typically, with larger rotors the braking force.

 

[Sandwich]

Am I missing some sort of logic that makes smaller rotors better?

50grams! Maybe more if you don't need to run an adapter, like you might on a fox or something.

One caveat, on an AM bike a 203 rotor might be overkill, especially in poor traction conditions. Makes it a bit too easy to lock up.

 

[IthonEng]

Sandwich, very valid post. 1.5 is the logical way to go until *add market giant* decides 2" steerer is better for little old johnny on his family ride. Cant keep up with them all!!

 

[Sandwich]

Sandwich, very valid post. 1.5 is the logical way to go until *add market giant* decides 2" steerer is better for little old johnny on his family ride. Cant keep up with them all!!

Nope, but you gotta try! I was running into similar issues recently. I had a perfectly good 1.125" frame, but all the forks were moving towards tapered steerers. I ended up selling the frame as I just couldn't find a good solution. My new frame has a zs44 (this is all XC stuff), and it's a lot more flexible...I can run a tapered fork if I want, but I have a 1.125" now.

My DH bike is all 1.125, and it's less of a big deal, but it's got a tall stack height and I can't slack it out the full 2*, if I wanted to.

 

[IthonEng]

I feel your pain!

Future proof as much as you can.

 

[kickstand]

Kickstand - Not wanting to drag my thread off topic but lighter guys could find the bike locks up too quickly with larger rotors. Its harder to moderate, typically, with larger rotors the braking force.

50grams! Maybe more if you don't need to run an adapter, like you might on a fox or something.

One caveat, on an AM bike a 203 rotor might be overkill, especially in poor traction conditions. Makes it a bit too easy to lock up.

I'm thinking for most this is certainly the very rare exception to the rule?

The AM thing makes sense, but I don't see very many "AM" class forks being made for 203 mm rotors only anyway.

 

[Huck Banzai]

I'm thinking for most this is certainly the very rare exception to the rule?

The AM thing makes sense, but I don't see very many "AM" class forks being made for 203 mm rotors only anyway.

I run 203/185 on my trail bike (sorta AM) -- but then I am >200 and was >250 when I built it.

I can definitely see a 140lb rider ejecting due to injudicious brake usage.