Disc Brakes

[dsut4392]

How do you - and Dirtyworks - define heavy?

I run DT Swiss 240s disc hubs on my MTB - and the "weight penalty" over the non-disc version is 40g each hub. Granted, as a percentage for the front, this is quite a big jump - but only because their front hub is ridiculously light!

As for the mass of the disc itself ... as people have said, you don't need the same sort of braking for cross that you want for (some) MTB racing - and the main advantage would be the modulation that you can get from a disc set up. With that in mind, why go anything bigger than a 140 at each end - and if you run Stans aluminium discs, that's about another 40g per wheel. (And who knows, in the future there may even be 120's or something similar if its demonstrated that they give all of the braking power needed for cross??)

So, that gives a total penalty of about 80g/wheel - granted, that's enough to get the weight weenies mega excited, but when most of the top pro bikes have "lower spec, heavy" parts for reliability (eg., check out the profile of Nys' bike on here from a couple of years back) and the choice of line on some courses can see that much mud being lugged around for a lap anyhow, is that really enough to write home about?

I think it'll be interesting to see what happens with discs in cross. I know there are times where I've wished I had the certainty of braking that they give - I can think of one course in particular where having the ability to carry more speed into a hairpin bend at the bottom of wet slope and do a bit of back wheel sliding to set me up for the nasty uphill pinch on the exit would be a real plus ...

I had to agree about something didn't I? I don't believe 80g at the hub is significant, but it's still 80g. Don't forget that with aluminium discs you lose some of the modulation compared to steel (steel is real).

I'm in complete agreement about mud buildup which is much less of an issue with discs - you collect less mud because it doesn't wedge against the brakes(=less weight), and what mud you do collect doesn't cause as much drag.

 

[DirtyWorks]

Last Time...

I was one of the first to adopt discs for XC racing in Australia at the National level in my team....

A couple of things going on in your post that deserve to be debunked. I'm repeating myself now, so this is my last post on the matter.

The summary: Gear addicts, I'm looking at you. IMHO the point of most gear addicts is to look the part. For those consumers, they are convinced they 'need' discs and probably quit reading the thread early on. The rest of you, keep on riding. It's fun and challenging. Focus on fun and challenging.

The gritty details:

1. Mountain biking is not cyclocross. In practice, a cyclocross course is so smooth a mountain bike is pure excess. Any halfway decent promoter in the world designs 'cross courses accordingly. Therefore, any mountain bikes experience applied to cyclocross aren't valid. The two disciplines are not analogous. Not even a little.

2. The bike industry will drive the switch to discs in 'cross. For casual riders, if discs get more people out riding their bikes, then great! For competitive riders, you are better off developing more Watts/kg and skills than buying another bike. A new bike will not get you out of mid-pack results.

3. Isolated geographic areas (very wet, not freezing) would benefit from discs. In the US, riders can ride discs in these locales and yet they don't. It has something to do with their lack of competitive advantage.

4. The unabashedly favorable disc brake replies have included other references to gear porn. "I'm waiting for", "I was the first", etc. That's great for the industry, but please acknowledge the strong bias is fertile ground for defending all kinds of dumb fads. Disc superiority in all competitive 'cross situations is the dumb fad in this discussion.

5. Discussing modulation is infinite (like riding conditions) and creates perfectly circular logic. Therefore its use in the debate is limited.

6. Mud. Sticky mud is the single area where discs will shine for other reasons. I'm charitably assuming the very rare course with some really rideable long, speedy sections in muddy conditions.
There you go. One rare situation where discs will be good. Do not then use that situation to create magical benefits in the other 99% of race conditions.

7. At the Nys/Stybar level, there was maybe one race last year where discs would have *actually* been a minor benefit. At the UCI level, they are a moot point at most races where pits are *filled* with bikes and mechanics. They'll show up at UCI races because the industry knows this is a big revenue opportunity.

 

[kiwirider]

A couple of things going on in your post that deserve to be debunked. I'm repeating myself now, so this is my last post on the matter.

The summary: Gear addicts, I'm looking at you. IMHO the point of most gear addicts is to look the part. For those consumers, they are convinced they 'need' discs and probably quit reading the thread early on. The rest of you, keep on riding. It's fun and challenging. Focus on fun and challenging.

The gritty details:

1. Mountain biking is not cyclocross. In practice, a cyclocross course is so smooth a mountain bike is pure excess. Any halfway decent promoter in the world designs 'cross courses accordingly. Therefore, any mountain bikes experience applied to cyclocross aren't valid. The two disciplines are not analogous. Not even a little.

2. The bike industry will drive the switch to discs in 'cross. For casual riders, if discs get more people out riding their bikes, then great! For competitive riders, you are better off developing more Watts/kg and skills than buying another bike. A new bike will not get you out of mid-pack results.

3. Isolated geographic areas (very wet, not freezing) would benefit from discs. In the US, riders can ride discs in these locales and yet they don't. It has something to do with their lack of competitive advantage.

4. The unabashedly favorable disc brake replies have included other references to gear porn. "I'm waiting for", "I was the first", etc. That's great for the industry, but please acknowledge the strong bias is fertile ground for defending all kinds of dumb fads. Disc superiority in all competitive 'cross situations is the dumb fad in this discussion.

5. Discussing modulation is infinite (like riding conditions) and creates perfectly circular logic. Therefore its use in the debate is limited.

6. Mud. Sticky mud is the single area where discs will shine for other reasons. I'm charitably assuming the very rare course with some really rideable long, speedy sections in muddy conditions.
There you go. One rare situation where discs will be good. Do not then use that situation to create magical benefits in the other 99% of race conditions.

7. At the Nys/Stybar level, there was maybe one race last year where discs would have *actually* been a minor benefit. At the UCI level, they are a moot point at most races where pits are *filled* with bikes and mechanics. They'll show up at UCI races because the industry knows this is a big revenue opportunity.

Looking through this thread, you're the only one who is taking an absolutist position here - I can't see anyone on here who has said that they are the panacea for all things braking in cross. Everyone else is more interested in why the UCI ban and what the change in the regs means for the development of this technology and how they'll ride. However you're in there like some sort of "canti-fanatic" trying to prove to everyone else that they're stupid - kinda like some medieval bishop trying to prove that "there be dragons" and that anyone sailing west too far will fall off the edge of the world! So, chill a little and try opening your mind a bit, ay? Otherwise, you'll come across as an overly dogmatic **** ... Oh wait, I'm at least one post too late for that warning ...

I will say before I go that, having actually ridden a bike with discs on it (a friend of mine in Ottawa has a Salsa alloy cross frame with Avid cable discs on it and we've done a couple of bike swaps during our training races while I was still up there) there are advantages to them in a number of situations. I didn't notice the extra weight (he's running 240s hubs with centrelock discs) and the ability to carry more speed into sharp corners - especially on wet or muddy courses - was great. Getting back on my bike - with normal cross brakes on it - after riding his would cause a few "oh ****!" moments while I adjusted to the different braking points needed and so forth. That said, I doubt that there would be any advantage on a hard packed, dry course.

Oh, and in case you're wondering how my buddy found it after a season of riding with discs - he didn't say directly, but he raved about the set up in general (he also changed some of his gruppo last season) and consistently finished about 5 places higher than he did the previous season ... So...maybe there's something in it ...

 

[Hangdog98]

Dumb fads

Discs are superior and will prevail.

News flash, cyclist are gear freaks, otherwise they would be runners.

The UCI banned CX discs to keep development costs down for frame manufacturers who didn't have disc compatible frames and would suffer commercial losses when the exodus to discs began. The delay allowed them time to catch up and, the catch up period is now over. Maybe SomeBody has a warehouse full of canti-only CX frames that will become a pile of unwanted triangulated pipes when the exodus to discs begins. Perhaps his brother in-law is one of those boutique manufacturers who doesn't have the engineering resources to make a competitive disc ready CX frame before the exodus to discs begins. Good luck with the 'cantis forever' campaign, oh, and Kodak called to see if you wanted to buy a truckload of 35mm film. It's way superior to digital you know

 

[dsut4392]

The summary: Gear addicts, I'm looking at you. IMHO the point of most gear addicts is to look the part. For those consumers, they are convinced they 'need' discs and probably quit reading the thread early on. The rest of you, keep on riding. It's fun and challenging. Focus on fun and challenging. .

Nobody "needs" any particular piece of gear, just like nobody "needs" to be told what they should focus on. FWIW, I go further than just arguing for "disc brakes" and say that it's hydraulic or nothing. Cable discs are just a second-rate solution.

"Average joe" would probably benefit more than Sven Nys from discs. They are incredibly fuss-free and reliable compared to rim brakes. Bleeding them can be a pain, but on one of my MTB's I haven't had to bleed them ever in 6 years (on my other MTB I have had to bleed them once in 4 years after a self-inflicted mistake). No messing about with pad placement, toe-in, cable stretch, no worries that when they wear they will start contacting the tire. No releasing the brakes to perform a wheel change, or bumping the pads out of alignment trying to force the wheel past them in a hurry. No worn out rims, despite enough riding that in rim brake days would have seen at least one set destroyed on each bike.

The gritty details:

1. Mountain biking is not cyclocross. In practice, a cyclocross course is so smooth a mountain bike is pure excess. Any halfway decent promoter in the world designs 'cross courses accordingly. Therefore, any mountain bikes experience applied to cyclocross aren't valid. The two disciplines are not analogous. Not even a little..

Riiiight... Just like F1 isn't MTB, and Rally-car racing isn't F1, and your every-day road car isn't Moto-GP, and motocross isn't aircraft landing gear...but they all use hydraulic disc brakes, because they're just BETTER. (incidentally some F1 braking is now regenerative, using capacitors to store energy then used to accelerate out of the turn...perhaps a good fit for CX)

2. The bike industry will drive the switch to discs in 'cross. For casual riders, if discs get more people out riding their bikes, then great!

I doubt anyone would argue with that [and if the bike industry didn't drive the change, exactly what would people be riding?] Seriously, the UCI have held up the change or the bke industry would probably have gradually got there already by now.

For competitive riders, you are better off developing more Watts/kg and skills than buying another bike. A new bike will not get you out of mid-pack results. .

Again few could argue with that, except in the few specific instances you allude to in points 6 and 7.

3. Isolated geographic areas (very wet, not freezing) would benefit from discs. In the US, riders can ride discs in these locales and yet they don't. It has something to do with their lack of competitive advantage..

It probably also has something more to do with the fact that race-worthy CX bikes with disc brakes are somewhat hard to find, no? "I'll take the one with Dura-Ace 7900 hydraulic STI. Don't have it in stock? OK, I'll take the SRAM Red hydraulic. WHAAAT, you don't have that either? Alright, alright, I'll run the Avid BB7 cable discs, just mount them up on my EC90 X fork. You're kidding, you want me to put that 900g alloy steerer fork on my race bike? Whatever, I'll take the one with the cantis."

4. The unabashedly favorable disc brake replies have included other references to gear porn. "I'm waiting for", "I was the first", etc. That's great for the industry, but please acknowledge the strong bias is fertile ground for defending all kinds of dumb fads. Disc superiority in all competitive 'cross situations is the dumb fad in this discussion..

Ad-hominem attacks do nothing to refute the arguments in favour.

5. Discussing modulation is infinite (like riding conditions) and creates perfectly circular logic. Therefore its use in the debate is limited..

In laboratory conditions, perhaps you have a point, but in the real world, the reliable modulation of disc brakes under all conditions is leagues apart from rim brakes. Don't mean to be rude, but have you ever actually ridden hydraulic discs?

6. Mud. Sticky mud is the single area where discs will shine for other reasons. I'm charitably assuming the very rare course with some really rideable long, speedy sections in muddy conditions.
There you go. One rare situation where discs will be good. Do not then use that situation to create magical benefits in the other 99% of race conditions. .

Sticky mud is the biggest area of advantage but discs have a significant advantage in any wet conditions, whether sticky, sloppy, sandy, or clean. Never had to brake hard on wet rims, or wet rims coated in sand? Never had to deliberately drag the brakes all the way down the hill just to ensure you had a bit of stoppint power at the bottom when you need it? Still think "modulation" is a circular argument?

7. At the Nys/Stybar level, there was maybe one race last year where discs would have *actually* been a minor benefit. At the UCI level, they are a moot point at most races where pits are *filled* with bikes and mechanics. They'll show up at UCI races because the industry knows this is a big revenue opportunity.

So one race where they could have made a difference in the positive (presumably due to heavy mud?). Now how many races where they could have made a difference in the negative? 0. Simply because CX racers can swap bikes at the pits does not make any advantage while out riding the course a "moot point".

 

[auscyclefan94]

 

[Boeing]

In Cross one could argue you don't need the stopping power of Disc brakes at the pro level

I am not a big fan of Cable Disc Brakes with Drop Levers either.

If one of these companies step up and make an STI Lever with Hydraulics things could change. But again do CX riders need that power?

 

[BrandonT]

Hey Guys

I am curious which size rear hub do you think will be used for the disc era of cross? Do you think it will stay at a 130 or will manufacturers move to a 135mm?

I think both sizes have their pro's/cons but I am curious to hear what you think.

BrandonT

 

[LugHugger]

Hey Guys

I am curious which size rear hub do you think will be used for the disc era of cross? Do you think it will stay at a 130 or will manufacturers move to a 135mm?

I think both sizes have their pro's/cons but I am curious to hear what you think.

BrandonT

good question! i've thought about this and think that this depends heavily on what model the volume frame builders adopt. if they do what most mtb companies did for about 10 years, they will build frames with both canti and disc tabs. given the relatively low number of 130mm disc hubs, imo they could adopt 135mm spacing to offer speccing options to individuals and merchandisers. the traditionalists will stick with 130mm and let individuals upgrade to discs as more hubs come to market. custom builders will do what customers ask - within reason

 

[RDV4ROUBAIX]

But again do CX riders need that power?

No, but we were saying the same thing back in the 90's when disk for MTB became available, now it's the standard.

Pros will ride whatever their sponsors give them. The question may be what ratio of pros will refuse to make the switch. I think more will adopt disk than not.

 

[DirtyWorks]

No, but we were saying the same thing back in the 90's when disk for MTB became available, now it's the standard.

Pros will ride whatever their sponsors give them. The question may be what ratio of pros will refuse to make the switch. I think more will adopt disk than not.

Comparing the mountain bike to a 'cross bike is poor reasoning. They aren't vaguely equivalent. Course conditions are nowhere near the same. My mistake was jacking up my rhetoric to try getting this point across. The comparison is going to happen anyway, but it's still weak.

Pros will be riding discs. This is a given. The industry wants the discs more than the riders need them.

 

[LugHugger]

Comparing the mountain bike to a 'cross bike is poor reasoning. They aren't vaguely equivalent. Course conditions are nowhere near the same. My mistake was jacking up my rhetoric to try getting this point across. The comparison is going to happen anyway, but it's still weak.

Pros will be riding discs. This is a given. The industry wants the discs more than the riders need them.

nobody is comparing mtb and cross. that would be like comparing motorcross bikes and mtb's - no? the comparison is with adoption of technology.

weight, and not performance, seems to drive this debate, - it would be interesting to note what the weight of early mtb disc systems was in comparison with modern systems. this would indicate where potential savings over current technology could take the debate to.

personally, i do not believe that pro's will adopt disc technology in the short term unless course design is impacted by the availability of discs and/or pit stops become punitive in terms of their affect on lap times.

 

[DirtyWorks]

nobody is comparing mtb and cross.

see RDV4ROUBAIX above. Other replies are littered with mtb comparisons.

 

[LugHugger]

see RDV4ROUBAIX above. Other replies are littered with mtb comparisons.

please read my post in full.

 

[Master50]

As soon as a disc equipped CX bike shows up at 6.8 kilos the flood gate will open.
1.3.019 b) Weight The weight of the bicycle cannot be less than 6.8 kilograms.

This rule applies to road, track and cx bikes

 

[kiwirider]

As soon as a disc equipped CX bike shows up at 6.8 kilos the flood gate will open.
1.3.019 b) Weight The weight of the bicycle cannot be less than 6.8 kilograms.

This rule applies to road, track and cx bikes

I don't know if the weight is as important as your post implies.

I mean, trawl your way through the various tech pages on the current and archived CN site and look at the weights of the various top pros' bikes that are listed there. They're not in the same "weight weenies" game as roadies are. For example, look at Nys' Colnago from a few years back as a classic for this - running a scungy old San Marco saddle and an Ultegra seat post. Could you imagine his equivalent in the road peleton doing that??? (On a personal note, I was surprised to see that my sub-$2k personalised Cannondale was only about 700g heavier than Jeremy Powers' same size pro team rig. Once I swap the fork for the WCS full carbon I got last year, the only real weight difference will be his carbon wheels - which is going to stay a difference for a long time ...)

Since the weight penalty for a disc bike doesn't need to be that great, I think that the determining factors for their adoption will come from other quarters - including the nature of courses (I can see them being much more use in a European mud fest or a snow race than a dry North American course for example) ... and of course commercial factors ...

And of course these comments don't apply outside of pro racing - where I reckon that the relative proportions of "weight weenies", "trendies" and "flat earth society members" will be the determining factor on take up rates ...

 

[DirtyWorks]

No, but we were saying the same thing back in the 90's when disk for MTB became available, now it's the standard.

Looks like a mtb comparison. Comparing mtb market segment with 'cross segment. How is that not a comparison? You aren't the only one doing it. It's going to sell *lots* of disc equipped bikes starting next season. (2011/2012) But it's still bad reasoning.

BTW, I agree with the rest of the comment. The first part is a major pet peeve of mine.

 

[RDV4ROUBAIX]

Looks like a mtb comparison. Comparing mtb market segment with 'cross segment. How is that not a comparison? You aren't the only one doing it. It's going to sell *lots* of disc equipped bikes starting next season. (2011/2012) But it's still bad reasoning.

BTW, I agree with the rest of the comment. The first part is a major pet peeve of mine.

"Bad reasoning"? Dude, you need to step back and take a deep breath. I was referring to progression in tech available to us, not making a comparison in disciplines at all. Question was asked: Does CX really need that much stopping power? No, but there's more to it than just stopping power. Does everybody need a disk brake system on their bikes just because all the pros will eventually all be riding them? Heck no, I'm crazy, but not insane.

Also keep in mind that some comparisons are unavoidable. CX, and eventually road are going to be all disk equipped, and this tech is directly taken from MTB. Many new touring bikes are adopting disk, and even some hybrids now all thanks to that dirty renegade MTB posse. In 1997 MTB'ers were all saying "don't need that much power, disk systems are too heavy", same thing that's happening now with CX. Why such confusion and irritation in response to a very general statement I made? have no idea. We're talking about disk brakes, yes?

 

[kiwirider]

"Bad reasoning"? Dude, you need to step back and take a deep breath. ... Why such confusion and irritation in response to a very general statement I made? have no idea. We're talking about disk brakes, yes?

RDV - give your fingers a break ... the same argument has come from the same quarter throughout this thread - and it hasn't got any more convincing over those posts. I'm trying to decide if they're a clever troll or just a dogmatic **** ...

Dirtyworks - if I've misjudged you, here's your chance to prove me wrong. Tell us what level of experience you've had with racing cross and racing or riding disc equipped cross bikes to be able to make your comments - rather than just the bald and dogmatic statements that you come up with at the moment. I'm more than happy to apologise for my characterisation and accept your arguments if you can convince me - but take it as read that you're not even off the starting line at the moment ...

 

[dsut4392]

Looks like a mtb comparison. Comparing mtb market segment with 'cross segment. How is that not a comparison? You aren't the only one doing it. It's going to sell *lots* of disc equipped bikes starting next season. (2011/2012) But it's still bad reasoning.

BTW, I agree with the rest of the comment. The first part is a major pet peeve of mine.

You still haven't explained satisfactorily what is actually wrong with the MTB comparison. Essentially every braked wheel, whether in any form of motorsport, aircraft, or bicycle (except for 'cross and road racing) is braked by a hydraulic disc. Cyclocross is much, much closer to XC MTB than XC MTB is to Formula 1. You're just not that special

 

[RDV4ROUBAIX]

I'm going to address a tech question that really isn't a comparison of MTB and CX, hopefully nobody's head explodes. I do believe that there are no hydraulic disk systems that work with road levers due to them being a much longer throw than an MTB lever, and where do you put the master cylinder?

Correct me if I'm wrong, all the new CX bikes I'm seeing are running mechanical disk. Cheaper, lighter.

 

[LugHugger]

I'm going to address a tech question that really isn't a comparison of MTB and CX, hopefully nobody's head explodes. I do believe that there are no hydraulic disk systems that work with road levers due to them being a much longer throw than an MTB lever, and where do you put the master cylinder?

Correct me if I'm wrong, all the new CX bikes I'm seeing are running mechanical disk. Cheaper, lighter.

I've only seen mechanical discs running on cx bikes too. haven't heard of/seen a hydraulic yet.

i guess you could run them on a single speed/downtube shifter/bar end shifter with the brake levers on the tops though it would take some getting used to. i would imagine that braking on the tops alone would compromise your ability to ride the fastest line on a lot of courses too.

 

[DirtyWorks]

You still haven't explained satisfactorily what is actually wrong with the MTB comparison.

In the simplest terms possible, the course profiles are so different there is no good comparison between 'cross and mtb.

Please don't generalize braking and then apply your generalization to 'cross. It's more poor reasoning.

 

[LugHugger]

In the simplest terms possible, the course profiles are so different there is no good comparison between 'cross and mtb.

Please don't generalize braking and then apply your generalization to 'cross. It's more poor reasoning.

i think that you need to be more specific about the braking conditions to which you refer. whilst it is correct to say that the typical cross course profile does not have sustained downhill sections where the increased braking power delivered by disks in mtb is of benefit, both mtb and cross take place significantly off road.

in these conditions rim brakes may offer a significant performance disadvantage when measured against disc brakes. this disadvantage - where mud is able to build around cantilever brakes from the tyre clearances affecting both braking performance and bike weight - should be seriously considered if conditions dictate that they are a factor. in wet/muddy (normal????) conditions, the extra weight of discs in a racers consideration of bike set up should be carefully weighed against the performance advantages.

for a privateer with one bike, this may swing the choice of frame towards a disc-equipped model - understanding of course that the current weight of discs will likely be a racing disadvantage in the early, drier part of the season.

of course, if you're a pro, you ride what you're told to ride and have the luxury of a pit crew to hand up a nice clean bike every lap.

both sides of the discussion would be served well by making reasoned specific arguments and avoiding specious generalisations.

 

[DirtyWorks]

Dirtyworks - if I've misjudged you, here's your chance to prove me wrong. Tell us what level of experience you've had with racing cross and racing or riding disc equipped cross bikes to be able to make your comments ...

Kiwirider: 'Cross rider for 20 years. I don't race any more. When I did, 'cross races were very few and very far apart. The fastest I ever got was 'very fast club-dude.' I still train with racers. I beat the local fashionistas at the training rides on something similar to this: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230483398135

25 years of mountain biking with my racing years in the past. I still ride and ride hard. The sweetest beat-downs are the carbon multi-pivot fashionistas versus me and my 10+ year-old gear.

I give up though. Despite the fact I'll be beating a couple people on the latest and greatest disc brake bikes next year. The flawed reasoning of many is no match for me. Enjoy your disc brakes.