Road bike with disc brakes.. should I build?

Aug 27, 2012
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#1
A friend sent me this link of a disc braked road bike -
http://www.bikeradar.com/road/gear/article/video-superbike-colnago-c59-disc-35290/ And it got me thinking....

Since getting to Tokyo I have bought myself a Hybrid with hydraulic brakes (which I absolutely love) for doing weekend bike rides. http://www.boardmanbikes.com/hybrid/hybrid_pro.html
Its fabulous and the spec actually delivered to me from wiggle was better than on the link above (Ritchy PRO OCR wheels, SRAM front mech, Fizik mag rail seat). On a ride last weekend I found I was concistently freewheeling down hill faster than the others on the ride with supposedly better road bikes (so much for the disc brakes causing resistance) but I miss the drop handlebars from my road bike left back in Blighty and suspect as I get faster the wind resistance won't help with a flat handlebar.

Where has this thinking got me.... building a roadbike with hydraulic brakes for reasonable cost.
I've seen this http://www.wiggle.co.uk/trp-parabox-hydraulic-cyclocross-disc-brake-kit/ which means I could use normal road shifter/brake levers

Any thoughts?
 

GSAstuto

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#2
Discbrakes are great! We have CX frames in either disc or cable. There are advantages to both. Overall, the db version, while heavier, offers more consistent and stronger braking under wider variety of conditions. I rode mine even in the snow here in Japan and love it compared to rim brake for ability to feather the braking.

Why would you use this TRP Hydraulic converter? There are quite a few good fully mechanical brakes on the market now - Avid, Tektro and now Shimano all make decent enough mechanical brakes for CX.

<Maybe> if I was a heavier rider on really grippy, fast courses I'd consider the hydraulic conversion. Or, if I was building up a special Rando / Touring bike and intended to carry more weight AND ride the Alps with long, multiple descents over 6% grade.

On the downside of discbrake -

1) Everything is heavier. If you ride CX then you know that weight does matter somewhat as you need to shoulder the bike. That extra kg can be a real burden to some.

2) You can't wheel swap with other riders or neutral support. Unless they happen to be carrying DB wheelsets - you are kinda stuck with what you brung.

3) Wheelswaps are slower. Especially if your fingers /hands are frozen and the bike is covered in mud and sleet. It will be easier and faster to simply have a spare bike in the pits.

4) More bits and pieces. Anytime you add complexity to a system it raises the chance of failure. DB are very reliable - but, I've snagged branches and stuff on mine and crashed on rocks bending the rotor, etc. Things that would not happen with a rim brake. For roadbike - risk of this is very low, though.

Upside of Discbrake:

1) Better stopping power under wide range of conditions
2) Better modulation than rim brakes
3) No issue to build Carbon rim wheels - so you can have your cake AND stop it, too!

A friend sent me this link of a disc braked road bike -
http://www.bikeradar.com/road/gear/article/video-superbike-colnago-c59-disc-35290/ And it got me thinking....

Since getting to Tokyo I have bought myself a Hybrid with hydraulic brakes (which I absolutely love) for doing weekend bike rides. http://www.boardmanbikes.com/hybrid/hybrid_pro.html
Its fabulous and the spec actually delivered to me from wiggle was better than on the link above (Ritchy PRO OCR wheels, SRAM front mech, Fizik mag rail seat). On a ride last weekend I found I was concistently freewheeling down hill faster than the others on the ride with supposedly better road bikes (so much for the disc brakes causing resistance) but I miss the drop handlebars from my road bike left back in Blighty and suspect as I get faster the wind resistance won't help with a flat handlebar.

Where has this thinking got me.... building a roadbike with hydraulic brakes for reasonable cost.
I've seen this http://www.wiggle.co.uk/trp-parabox-hydraulic-cyclocross-disc-brake-kit/ which means I could use normal road shifter/brake levers

Any thoughts?
 

bloaker

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#3
Avid BB7s are great! You can adjust pad spacing on both sides. On my MTB, I have dinged up the rotor pretty good and made a trailside adjustment - and good to keep going.

Also... in the event of knocking your wheel out of true, you can limp the bike along without the annoying brake rub.

My wife has BB5s on her touring bike. They are not as adjustable as the BB7, but on a touring bike we have yet had any issue that might require an adjustment. All said and done, you are a 4mm allen away from any adjustments needed.

My touring bike has BB7s - and much like the mountain version, very adjustable and reliable.

I also prefer cable disc since I can adjust on the fly. I can also adjust my lever to engage where I want.


Both of our bikes are 135 spacing. This is nice because we can use any mountain rear hubs we want. There are far more disc hubs in a 135 vs 130 at the moment.
 
Aug 27, 2012
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#4
@bloaker I've heard a lot of good things about the BB7's and agree with all your comments. If I went cable disc route then I would definately use them as my weapon of choice. I hadn't noted the hub width difference before so thats really useful to know
@GSA I've had cable disc before and also cable to hydraulic cylinder (both on MTBs). Both were good and easy to maintain. Most people (including you & me) would say hydraulic for powerful breaking with heavy loads, but what I would characterise my current hydraulic brakes as providing, is more confidence with (thin) road tyres (e.g. maximum braking without locking up) than the cable versions. I'm not up on my bike terminology yet, but I think what I mean = "better modulation" (?) on my hydraulics. Suspect thats why the Colnago in my top link has them on a bike weighing less than 8kg

I hear (but don't know) CX frames tend to be more upright geometry and I guess they are built slightly stronger and hence heavier than pure road frames? I noticed the CX Boardman Pro (note, using BB7's) is a Kg or so heavier than my bike which I suspect is the weight in the frame. Makes me wonder if i should convert my Hybrid to drops? Or, GSA, what would a no thrills carbon CX frame set me back from your shop?
 

microcord

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#5
. . . I have bought myself a Hybrid with hydraulic brakes (which I absolutely love) for doing weekend bike rides. http://www.boardmanbikes.com/hybrid/hybrid_pro.html
Its fabulous [. . .] On a ride last weekend I found I was concistently freewheeling down hill faster than the others on the ride with supposedly better road bikes (so much for the disc brakes causing resistance) but I miss the drop handlebars from my road bike left back in Blighty and suspect as I get faster the wind resistance won't help with a flat handlebar.

Where has this thinking got me.... building a roadbike with hydraulic brakes for reasonable cost.
Sounds to me as if you already have a road bike with disc brakes but a flat handlebar. Why not just change the handlebar?
 

bloaker

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#7
Flat bar brake levers and drop bar brake levers , different mechanisms.
Very true, but bars, brifters and brakes are less money than new complete bike...
Unless you are like me... and it is just an excuse to add another bike.

Truthfully I am 'anti' just switch the bars -
If you were fit for the bike - your upright preference and your aggressive preference will not result in the same frame.
 

microcord

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#8
Flat bar brake levers and drop bar brake levers , different mechanisms.
Yes. Well, change the brake levers (and for that matter maybe the stem too) together with the bar.

I've never tried disc brakes on a pushbike. I read above that yes, they have certain advantages (and disadvantages). Y'all no doubt know what you're talking about. Nevertheless.... For a given angle of rotation, the surface area of the disc is very small. And the circumference of the outside of the disc is tiny compared with the circumference of the wheel. My hazy memory of applied maths tells me that these factors will tend to result in a very inefficient method of stopping. (Different for cars, where the disc is a lot bigger and the wheel a lot smaller.) There may be contrary factors, of course. Still, I'm puzzled. (It probably all goes to show that my maths "intuition" is even less valuable than I suppose.)

Have you thought of forks? This points out:

With rim brakes forks are loaded in bending at the fork crown that similarly supports road shock, while a disc brake places an equal bending torque at the tip of the fork and only on one blade. The fork can only be slender and light because it carries no bending loads at the dropout. With disc brakes forks would require a substantial increase in cross section (and weight) and brake would be heavier.
 

GSAstuto

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#9
Well, I'm kinda mixed on the whole CX thang - cause my background is really that CX is what you do in the off season to have a kick time and get in top shape. But now CX is really popular and has alot of top riders competing, yadda yadda , so it's more than that. But anyway - the CX stylee is more about taking a road bike and repurposing it for whatever. So - you run with it, throw it, crash it, anything, to get you and the bike through the course. On the other hand - you DO see some MTB'ers especially hardcore XC actually adding drop bars to their hardtails so they can get more speed efficiently on smooth, fast sections. And MTB / XC is very very popular - even as a group - on the CX circuit! So - it's not so much what's proper - it's more about what you dig. As for me - cranking out 100+km on varied terrain on flat bars would be more tedious than if I had drop bars. But that being said - alot of riders feel the exact opposite.

Only thing I can say , is that discbrake is much better in all respects , for braking, than rim brakes. Except for maybe TT and specific wheel builds where you want the absolute lightest possible. Like I wouldn't be a fan of DB for crit bikes or dedicated HC stages.

In fact I just built a couple of custom Ti rando bike frames and guess what? Yeah - they have discbrake mounts.

And after doing the Haute Route in the Alps - I can tell you , I'd happily trade 1kg for discbrakes on many occassions. hey, I'm old<er> and quite honestly, having numb arms at descents over 70kph is simply painful and scary. No reason to suffer this - with DB, I'd be using a fraction of the effort to control the speeds - especially into the hairpins.

@Bloaker - yeah - frames are built to suit a particular stack and reach. So, just swapping out bars drastically changes that geometry. So - you need to be somewhat in the fit zone for either / or to make this work. (Like the MTB examples above). They are really different animals from the get go.
 

bloaker

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#10
Rim brakes.... I can lock up my old MTB and my current road bike at any given second... unless it is raining, snowing, etc... At that point, I might as well shove my shoe into the wheel in an emergency cause I am screwed.

A set of V Brakes on a mountain bike will stop a bike - no doubt!

But for me, the advantage has always been the 'foul weather' bad conditions type rides. If I plan to ride on Saturday - I don't care what the weather does, I am riding. On road or off.

The disc gives me more modulation than a rim brake in all conditions, but still works in bad conditions. V-brakes give me more lock up power only in perfect conditions.

Are disc brakes necessary? - Of course not. People are survived on inferior brakes for decades. But why not embrace something new and proven if you are to go the route of something new?

That said - my disc brakes work awesome on my steel mountain bike and my steel touring bike. Some things have a feel to them you always come back to... no matter what the latest and greatest may be.
 

GSAstuto

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#11
I love my discbrake CX in snow and cruddy weather just for that reason! Plus the fact that you can actually stop the bike if required! And it lets me build some really bitchin' carbon wheels that simply not be practical or durable with rim brake.
 
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#13
And then you aren't going to be able to use hydro discs. The OP wants to put drop bars on his hydro disc bike, not possible at the moment.
Surely the point of the original post is that you can have hydraulic brakes and brifters, thanks to the cable-to-hydraulic converter. I can't speculate on whether this is a good idea, but it's possible.

I worked on someone else's hydraulic (rim) brakes last Xmas. The bike had been horribly abused along its ride from London to Tokyo, and both brake lines were falling apart. The maintenance/replacement of parts was straightforward enough, but it's very hard to McGyverise these systems if you get problems in the middle of a ride.

A cable + disk setup should modulate just fine if it's looked after properly.
 

kiwisimon

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#14
Surely the point of the original post is that you can have hydraulic brakes and brifters, thanks to the cable-to-hydraulic converter. I can't speculate on whether this is a good idea, but it's possible.

A cable + disk setup should modulate just fine if it's looked after properly.
I thought he wanted to swap out his flat bars for drops which would mean buying new brifters bars stem and the adapter kit making his present brakes redundant.
 

FarEast

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#15
To be honest after reading all the reports - all the feedback and other stuff out there on disc brakes on thoroughbred road bikes or standard high performance road bikes I just don't see the need - of course a disc brake will be mostly benifitial to people that can't descend or brake properly but again in reality caliper brakes work perfectly fine.

Yes there is the argument about riding in the wet or snow etc - but lets face it unless you are barking mad you're not going to be out in the snow on your 700 -23c's and you will be out enjoying the fluffy stuff on a bike designed for this kind of riding - such as a CX bike.

Now going to CX - I've spoken to a couple of friends that are CX pro's about this as I will be getting a team CX bike for Nobeyama and Tokyo CX and they asked canti or disc. For most short course CX races there is no real need for disc on long races then disc brakes are a must.

So whats the conclusion - different tools for different jobs. There really is no need for the fair weather cyclist to need a road bike with disc brakes, unless of course they have poor bik handling skills and ride the brakes down any incline.

Cross Country or CX - I would be more inclined to ride disc, we use them in SC CX races and the benifits of disc out weigh the cons - mud clearance for one - but hey if you are racing you should be bringing spare kit - if you don't will thats just the way it goes.

In regards to the parabox - wouldn't waste my time on it, give it some more time and hydro STI units will hit the market and I've never been one to jump on transitional tech
 

joewein

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#16
I would love to have disk brakes simply not to have to worry about overheating the wheels on steep winding descents.

With rim breaks all the friction heat hits right next to the tubes and tyres. Rubber does not particularly enjoy heat and the air pressure will spike when the air inside gets heated.

With disk breaks you don't really care how hot the rotor gets: in race cars rotors will sometimes glow red hot without failing. The hotter they get, the more heat they will dissipate quickly. I'd rather have a hot brake rotor than an exploding tyre on a 70 km/h descent.

The other major argument is foul weather. I went for a 46 km rain ride last Saturday. On the empty bike path it wasn't too bad, but on roads with cars and other vehicles around me I was only too aware how much less effective my wet rim brakes were in the rain whenever I had to use them.
 
Aug 27, 2012
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#17
of course a disc brake will be mostly benifitial to people that can't descend or brake properly but again in reality caliper brakes work perfectly fine.
I remember something similar being said when ABS brakes came in for cars and the analogy still stands today that a pure bred lightweight single seater won't have ABS. I had my mind changed when as a (young) engineer my car manufacturing employer gave me the chance to drive cars with and without ABS at a plastic brick wall with the passenger allowed to say when I could hit the brakes and try to stear round the wall.

I'm sold on disc brakes for bikes but have no intention of trying to push my beliefs on to others. My OP was to try to identify a way forward for me to have a disc brake bike, designed as much as possible for the road (relatively lightweight with drops). Not yet clearer whether that is convert my current bike \ start from a CX frame \ beg Tim to build me one of his gorgeous Ti frames with db attachment points, but the information/advice provided is helping me to avoid expensive mistakes (TY!)
 
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#18
beg Tim to build me one of his gorgeous Ti frames with db attachment points, but the information/advice provided is helping me to avoid expensive mistakes (TY!)
As a Timtanium rider, I would say, without hesitation, do this. It's always going to be much better to have something designed for purpose than retrofitted. And then you have a spare bike. (Depending on your storage issues, this might not appear to be an advantage, but see Rule 12)
 

FarEast

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#19
I remember something similar being said when ABS brakes came in for cars and the analogy still stands today that a pure bred lightweight single seater won't have ABS. I had my mind changed when as a (young) engineer my car manufacturing employer gave me the chance to drive cars with and without ABS at a plastic brick wall with the passenger allowed to say when I could hit the brakes and try to stear round the wall.

I'm sold on disc brakes for bikes but have no intention of trying to push my beliefs on to others. My OP was to try to identify a way forward for me to have a disc brake bike, designed as much as possible for the road (relatively lightweight with drops). Not yet clearer whether that is convert my current bike \ start from a CX frame \ beg Tim to build me one of his gorgeous Ti frames with db attachment points, but the information/advice provided is helping me to avoid expensive mistakes (TY!)
In no way would I compare ABS breaking to disc brakes, veeeeery different.

Although I have to say i'm coming from the other side of the fense where I'm purely looking at this from a racing/minimal gains point of very and right now disc just doesn't offer anything new to the table.

Joe - yes although you are right I'm guessing you have never used disc brakes some serious down hill and experienced chronic brake fade and egg cooking rotors?

http://www.youtube.com/watch?v=QiomMvB7lJc

Remember the standard caliper system is one big disk brake and your rim is one BIG rotor!

Anyway back to the question at hand, I would agree with Mike. Have something built up specifically for the job. There is no point in modding as you end up spending more in the long run.

The other option open to you is basically a CX bike and just running it with slick - There are plenty of new carbon frames hitting the market now that do not have the bosses for cantilever brakes so you keep the stunning lines.

It also means you can switch over the tyres or wheels and use the bike off road.
 

GSAstuto

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#20
Discs have been negged in the past due to the need for hydraulics and weight. That is pretty much passe these days as the current revs are light and you can get decent cable actuated versions. One bike we set up just went this summer from Japan to Australia. Cannondale BadBoy that I built up 26" DB wheels for - and used Shimano mechanical DB. The rider is heavy and the load was even heavier. It seemed to work fine. (And still is).

DB are a bit of a luxury overkill on the typical roadbike. Agreed with FE, you really don't need them as the old tried and trued clincher brake aint that bad.

But they really start to make sense when / if you have reason to require extra duty braking or conditions that are not always favorable to the rim brakes.

Alot of frames these days have DB ISO mounts so you should be able to cover both cases. And more hubs come in both 130mm and 135mm with wide variety of drillings.

Quite popular right now is building front dynamo / disc wheel and rear db wheel using Ambrosio Excursion rims or Niobium Alloy CX rims with tubeless conversion.

CX specific bikes tend to have longer chainstays, less trail, horizontal top tube (higher standover for easier shouldering), canti brake mounts and generous tire / wheel clearances to allow up to 35C (33mm UCI limit), drop-style bars and all 'top pull' cabling. Like MTB, you don't want cables running under / below tubes. They get snagged on the barriers or torn off completely. These details also make some sense for the randoneur who likes to explore the off-the-road rindos, etc. Just add some rack / fender mounts and voila!