Road Bikes with Disc brakes

Alistair Hey · Post by **Alistair Hey** » 13 Jan 2013 00:08

What are peoples thoughts on this? I'm surprised that there are not more 'standard' road bikes equipped with them...

After buying my first (very cheap!) bike, i'm planning to upgrade around Easter and wouldn't consider anything that didn't have disc brakes (although 80% of my riding has been in wet weather so that may have something to do with it!) but i'm finding it hard to locate a sensibly priced (£500-£700) road bike with them.

Also, a quick question (may be a stupid one) what, apart from thicker tires, is the difference between a CX bike and a road bike? (im talking in the price range above...)

any input would be appreciated!

laurence_cooley · Post by **laurence_cooley** » 13 Jan 2013 11:01

I imagine the main reason that they're not more widely available is that they're not legal for use in UCI-approved events. Obviously someone buying from Evans or wherever isn't going to enter the Tour, but most of what you see on even relatively cheap bikes has trickled down from the top-end ones that are designed for the pros. There's a recent article on them here, if you haven't seen it.

I'm not really looking forward to the day that disc brakes are commonplace on road bikes, if it comes. Judging by the ones on my mountain bike then, yes, they stop you quickly (I've got the scars to prove it) but they seem to require constant adjustment to stop them rubbing and squeaking.

ripebuds · Post by **ripebuds** » 13 Jan 2013 12:39

I used disc brakes on my first road bike from 2010 to the 2012, but only because that's how I bought it (it was marketed as being a city hybrid, and I installed the drop bars myself). I now ride with rim brakes and much prefer it, especially on long descents. Disc brake stopping power isn't really necessary on the road IMO. Disc brakes get so hot and I agree with Laurence in that I was constantly having to adjust them and deal with their squealing. Disc brakes are much more efficient in the wet but I rarely need to slam on my brakes and if it is wet I will allow myself more stopping time.

There have been a couple of occasions where having discs has been really useful though, for example when I was on tour in the middle of no where and had a crash, my wheel was majorly out of shape which would of meant it would of been unridable with rim brakes but was no problem with discs. These situations are rare though.

Alistair Hey · Post by **Alistair Hey** » 13 Jan 2013 13:29

I find even in the dry that i have inadequate stopping power, have replaced my pads with much more expensive ones than the ones that came stock. makes me fell uneasy when riding fast around the city (on strait descents with the chance of people pulling out).

i clean and service my bike at least once a week so constant adjustment is not that much of an issue for me.

George · Post by **George** » 13 Jan 2013 16:45

They are commonly fitted to non-racing tandems (often as a third brake along with two cantilevers) and definitely provide extra braking power.

As well as the reasons for not fitting them mentioned above, the obvious ones are weight and additional asymmetrical torsional force on spokes. Furthermore, a solo road bike simply doesn't need them in normal conditions: ordinary dual-pivot brakes work fine. However, I have sometimes thought that it would be a good idea to have them on a touring bike, especially if you expect to sometimes ride in hilly areas in the wet.

Grogz · Post by **Grogz** » 13 Jan 2013 16:50

What brakeset and pads are you running, Alistair? You may find that upgrading these would be as effective. I use SRAM Rival - which are powerful - and have used SwissStop Green (OK, but seem to pick up lots of aluminium from the rims and are expensive @ £20/pair) and now use Halt Gooey (cheap @ £5/pair, soft compound that work really well, wear more quickly but don't damage the rims). I know others swear by Kool Stops.

CX bikes have greater clearance between wheels and frame/forks for wider tyres and to reduce mud build up. Many CX bikes run cantilever brakes, which are marginally better than blowing in the wet. UCI made discs race-legal last year, so more are available. There are pluses and minuses for racing, though, as the bikes are heavier and stopping on a sixpence isn't always necessary. But you might avoid so much mud build up...

AlanW · Post by **AlanW** » 13 Jan 2013 17:24

From someone that rides pretty much all year round, road rims are getting thinner and thinner as manufacturers consistently strive to reduce the weight of wheels.

The nett result is that a Open Pro rim for example will last me around 4000 miles, and that's using rim friendly Koolstop brake blocks.

Furthermore, the condition of the lanes over the last few weeks will more than likely reduce that even mileage further.

As an aside but I no longer use Open Pro rims, I have since opted for the Open Sport rim as the rims are a touch thicker and a lot cheaper!!

So from that perspective, disc brakes make perfect sense to me as all I will then need to do is replace a set of pads as opposed to having complete wheels rebuilt.

Weight? Well the bike is already fitted with twin headlights, a heavy weight battery, saddle bag and carrier, plus a fat rider, so am I really that worried about the extra weight??

Plus the fact, if you then apply the same amount of effort when you jump onto your carbon bike......you'll fly!

Not to sure why there should be any additional stress on the spokes though, the disc is attached direct to the hub?

George · Post by **George** » 13 Jan 2013 17:35

AlanW wrote:So from that perspective, disc brakes make perfect sense to me as all I will then need to do is replace a set of pads as opposed to having complete wheels rebuilt.

Weight? Well the bike is already fitted with twin headlights, a heavy weight battery, saddle bag and carrier, plus a fat rider, so am I really that worried about the extra weight??

Yes, I think that's fair enough, Alan. I think that the riding and the bike you describe is broadly what I had in mind when I talked about a touring bike. I think of something a little lighter and less cluttered when someone says 'road bike'.

AlanW wrote:Not to sure why there should be any additional stress on the spokes though, the disc is attached direct to the hub?

I fear I'm not the best person to answer this, but I think the replaceable disk attaches to a bracket and the bracket is attached to the hub, so I would imagine that the forces involved in braking are a little like the forces on the back wheel when you pedal.

George · Post by **George** » 14 Jan 2013 14:03

I don't think I made myself very clear there. Back wheels snap spokes more often than front wheels (crashes/pot holes notwithstanding) because a rotational force is applied to the hub, while the rim is subject to a restraining force (friction with the road). That causes strain on the spokes, which can eventually cause them to snap. I imagine (but this is speculation on my part) that with a disc brake there is a similar situation in reverse. However, I have no idea how you would calculate the forces involved and I wouldn't be surprised if someone who did know how to calculate them said that the resulting strain on the spokes is well within what they can safely handle.

Philip Whiteman · Post by **Philip Whiteman** » 14 Jan 2013 14:21

MODERATOR'S NOTE:

I have just shunted this thread to the Technical Forum. It is an interesting technical discussion that would otherwise be lost in the general chit chat of 'Cakestop'.

EDIT

---ooops. I meant Cafe Stop and not Cakestop (see below)

Alistair Hey · Post by **Alistair Hey** » 14 Jan 2013 23:42

Grogz wrote:What brakeset and pads are you running, Alistair? You may find that upgrading these would be as effective.

im on kool stoop things atm, with very cheap (stock on a £300 bike) rims. got a set ofmavic aksiums for febuary onwards.

just find that personally, on a very heavy (11kg, im 6"2 so large frame size, without my water; saddlebag and pannier rack) bike, that rim brakes just dont stop me quickly enough, id rather lug 500g extra from disc brakes up a hill (and be fitter for doing it) and be able to stop if needs be on the way down...

i should probably just find a cheap cross bike (with disc brakes) for an upgrade on my bike and strip the current one down for a more 'sporty' bike for when i need it.

George mentioned spoke tensions, i would hope that wheel manufactures took this extra stress into account when building disc specific wheels! spokes only usually brake after large distances or neglect so how much can discs really reduce their life?

EDIT:wrong currency i put $...

George · Post by **George** » 15 Jan 2013 10:39

Alistair Hey wrote:George mentioned spoke tensions, i would hope that wheel manufactures took this extra stress into account when building disc specific wheels!

I'm sure they do, Alistair. But you asked why disc brakes weren't normally fitted to road bikes, and it crossed my mind that part of the reason might be that (for the reasons explained) that would involve beefing up the wheel a bit to make it "disc specific", which many would regard as undesirable. That's all I was trying to suggest.

Alistair Hey wrote:spokes only usually brake after large distances or neglect so how much can discs really reduce their life?i put $...

As I said above, I don' know ... I was just wondering out loud. However, when I was in the habit of putting my wheels under a bit more stress than I do now, a back wheel rarely lasted me more than about 2 years before it stared snapping spokes.

Tim · Post by **Tim** » 15 Jan 2013 11:10

I would agree with Greg that you may think differently with different group set. I have shimano 105 and have never thought I needed quicker stopping. That includes commuting when I have needed to stop v quickly in the wet and on long descents in pyrenees.

Also I have heard and said it myself "better to be bit heavier as it will work me harder" but having now ridden a road bike for three years I would totally say this isn't actually the case as on a lighter/better bike you will cycle more, over more hills, over greater distances for more hours. I now cycle 5-7hours a week becuse the bike is lighter and more enjoyable to ride.

Maybe test ride a tiagra or 105 groupset in the wet and see what you think of brakes.

My mavic aksiums lasted c10000 miles before being deemed "dangerous and worse worn wheels ever seen" but they were almost never cleaned and used year round

Alistair Hey · Post by **Alistair Hey** » 15 Jan 2013 18:23

i hadnt actually thought of groupset.

after looking they are only 'btwin' , Decathlon's home brand... so probably leave a lot to be desired... upgrading the pads made a huge difference but not enough.

laurence_cooley · Post by **laurence_cooley** » 01 Feb 2013 08:07

According to an advert in ProCycling, March 2013's Cycling Plus has a group test of road bikes with disc brakes.

Alistair Hey · Post by **Alistair Hey** » 01 Feb 2013 08:54

read that test yesterday, not really in my price range, £2000-4000

George · Post by **George** » 01 Feb 2013 10:32

There was also a road test of disc-brake tourers in a recent CTC mag. Not sure whether that's available on line, but you might look on the CTC website and/or try to borrow a copy.

laurence_cooley · Post by **laurence_cooley** » 22 Feb 2013 15:34

There's also an article on the technical hurdles involved in adopting disc brakes in March's Procycling. A not very-well-scanned PDF copy is here.

Tim · Post by **Tim** » 22 Feb 2013 19:00

http://road.cc/content/feature/72743-di ... er-comment

http://road.cc/content/news/76756-revea ... are-coming

HAZBRO · Post by **HAZBRO** » 22 Feb 2013 19:19

All that work that shimano did getting the perfect gear set and brake movements with their di2 set, now they must set to work on electric disc brakes in order to fight of any competition, what will the pros opt for, as disc brakes can be way lighter than calipers brakes etc

laurence_cooley · Post by **laurence_cooley** » 22 Feb 2013 19:34

I'm pretty sure that disc brakes are heavier! Not only the brakes themselves, but they require heavier forks and wheels with more spokes. The pros don't really have a choice at the moment as disc brakes aren't sanctioned by the UCI for the road. One of the articles I linked to above makes the point that in cyclocross, disc brakes have taken off much more amongst amateurs than pros.

HAZBRO · Post by **HAZBRO** » 22 Feb 2013 19:44

I would of thought a carbon disc along with some altherations and optimizations with the frame can actually mean a lighter bike, but at the end of the day, its only grams we are talking about, so if someones got thousands of grams round their waist then its pointless in terms of weight saving

rdleaper · Post by **rdleaper** » 22 Feb 2013 22:50

HAZBRO wrote:if someones got thousands of gram round their waist the it pointless in terms of weight saving

...but if someone's got thousands of pounds of spare cash they might just do it anyway

HAZBRO · Post by **HAZBRO** » 22 Feb 2013 23:11

rdleaper wrote:...but if someone's got thousands of pounds of spare cash they might just do it anyway

I'm not sure what country your living in because i never knew their was such a person, this is Great Britain we are talking about, populated by snobs in this time of recession,and the home of beggars and thieves, our contribution to the world cuisine was the chip, I honestly can't think of anyone who has thousands of pounds spare! (apart from Wayne Rooney he may have a few million tucked away)

dweben · Post by **dweben** » 23 Feb 2013 01:02

Yah discs are pretty heavy compared to rubbish roady brakes (god I hate them!)... down to heavier calipers/ levels, braided hoses, the hydraulic fluid, etc. The standard rotors are usually just laser cut steel but you can buy lighter 'floating' rotors at great expense.

Don't think the wheels are really any heavier... the rims can be better machined as they don't wear out and the extra machining is done in the hub. Don't need more spokes either, check out crank bro mtb wheels... same spokes are my ultegra setup and in a weird pattern!

Economically they're superior, the rotors last forever unlike the rims on wheels. Only need to change the pads, and on the road the pads last thousands of miles and winter conditions are irrelevant aside from the squealing noise.

I've thought about converting the front of my roadie bike to discs. I have a spare caliper, can use normal levels, just need a fork and wheel.

laurence_cooley · Post by **laurence_cooley** » 23 Feb 2013 10:54

The Procycling article claims that removing the need for a brake track will make rims lighter, but that they'll need more, tougher spokes and reinforced spoke holes. Maybe they're wrong about the extra spokes if there are MTB wheels out there without them, though.

HAZBRO · Post by **HAZBRO** » 26 Feb 2013 14:25

new carbon fibre disc brakes just in!
http://www.bikeradar.com/news/article/k ... -in-36555/

AlanW · Post by **AlanW** » 26 Feb 2013 14:46

HAZBRO wrote:new carbon fibre disc brakes just in!
http://www.bikeradar.com/news/article/k ... -in-36555/

Given the fact how crap carbon rims work in the wet, it will be interesting to see how well they dont work in the wet either?

dweben · Post by **dweben** » 26 Feb 2013 22:47

Will be interesting... F1 cars run carbon brakes and they seem to work ok!

keith · Post by **keith** » 26 Feb 2013 23:31

F1 brakes only really work when they glow red hot

AlanW · Post by **AlanW** » 27 Feb 2013 09:46

dweben wrote:Will be interesting... F1 cars run carbon brakes and they seem to work ok!

Aerofoils next then....

Grogz · Post by **Grogz** » 27 Feb 2013 21:21

So when you lean your bike at a café stop and catch the brake rotor, it won't fracture? I guess you won't need to carry too many spares and tools to replace it?

Dave Cox · Post by **Dave Cox** » 27 Feb 2013 23:01

Red Kite had a nice Whyte road/cross bike with discs and Richard Kent's rarely seen Boardman winter bike has discs and he likes it - but he now overwinters in Goa. Both are clearly heavier duty than the average road bike.

HAZBRO · Post by **HAZBRO** » 27 Feb 2013 23:07

keith wrote:F1 brakes only really work when they glow red hot

Portable Bunsen burners 'pinarello style' should be fitted onto the frame with a gas supply under the seat, just like the gear wiring internal tubing can be used to transport the gas, well they do have to be red hot to work properly, well here's your answer, ahhh but they may be disallowed in uci pro races as they can be used an a afterburner to gain speed, just an idea!

Alistair Hey · Post by **Alistair Hey** » 23 Jun 2013 22:30

problem solved:

http://www.eastwaybikes.com/product/eas ... -road-bike

mines already on order.....

laurence_cooley · Post by **laurence_cooley** » 23 Jun 2013 22:39

Looks good. That £500-£700 budget quickly went out of the window!

Alistair Hey · Post by **Alistair Hey** » 23 Jun 2013 22:44

rapidly

dweben · Post by **dweben** » 23 Jun 2013 22:52

i have bb7s on my commuter bike. they're pretty nice... hope you can tolerate the wet weather screeching from sintered pads in the rain...

Alistair Hey · Post by **Alistair Hey** » 24 Jun 2013 11:39

it wont be out in the rain

Andy_Craddock · Post by **Andy_Craddock** » 24 Jun 2013 22:50

Alistair Hey wrote:it wont be out in the rain

Yea right!!

Ive got some nice tyres that would go with that bike

Moss · Post by **Moss** » 26 Jun 2013 00:39

I've been wanting disc brakes on my road bike for a long time.

The spokes WILL have to change though.

Yes, the disc is attached directly to the hub but the stopping force is applied to the tyre (rim), this creates a rotational stress on the wheel meaning that spokes running from near the centre of the hub will generate a lot of rotation for little tension change of the spoke (bad). Like holding a weight from the end of a horizontal match-stick being held at the opposite end.

For rim brakes the stopping force and the momentum of the bike both act on the rim, the stress isn't rotational. Instead it is created as a force pulling the wheel back (in relation to the bike) meaning that the spokes get to act in the same way they normally do by supporting the attempted shift of the wheel except this time it's on the spokes at the trailing edge of the wheel (the wheel is trying to push backwards). The amount of rotation / tension change is small. Like propping up a weight on top of a matchstick, much stronger.

Some wheels will never be good for disc brakes, e.g. any with tiny hubs as there isn't enough offset leverage to create the all important ratios needed for tension / rotation. To offset the stress the hub would need to be larger and the spokes crossed to create a push/pull force.

It is possible to run without changing the spoke pattern but this would result in a spongy brake feel that has a delayed reaction and snapback on release, plus it would collapse inwards once the force was enough - A lot more force is generated by stopping than by accelerating, no matter how powerful you are. You dont see rear wheel with tiny hubs and none crossed spokes for a reason.

I have an unhealthy obsession with physics.

dweben · Post by **dweben** » 26 Jun 2013 00:52

Why would you run a disc hub on a rim brake rim anyway? That way lies insanity!!

The brakes are the thing I dislike on road bikes. Having been brought up and raised on hydraulic discs I almost crashed into a roundabout when I got my first road bike 'cos they were quite frankly totally useless at stopping me, in the dry too! Mean, what's up with putting the pivot point of the lever (when on hoods) right by your hand?! Nutters.

Discs do require a bit more maintenance but they're jolly well worth it. Not sure how much use hydraulics on thin road tyres would do -- might just mean more skid related issues. Mega plus side is a worn out rotor (never seen one) costs £30 to change unlike a new set of rims/wheels

Mega down side -- even at a 66% discount my brakes cost £150.

Alistair Hey · Post by **Alistair Hey** » 01 Aug 2013 16:53

the eastway went our of the window when i found out there was an 8 week delay. aint nobody got time for that- have bought this instead

http://www.canyon.com/_en/roadbikes/bike.html?b=3081

and its already been shipped. roll on monday

Kev C · Post by **Kev C** » 01 Aug 2013 17:19

Fantastic bike at a fantastic price. Enjoy!

laurence_cooley · Post by **laurence_cooley** » 01 Aug 2013 17:49

So not only did the budget go out of the window, so did the disc brakes! Looks like a good choice - a lot of bike for the money.

deero83 · Post by **deero83** » 06 Aug 2013 10:46

Just been reading the discussion about brakes.

On a slight tangent, my "cross" bike (I say cross, it's a road bike with cantilever brakes really) which I use as my winter bike/commuter has horrible juddery brakes.

It's got KoolStop red pads on at the moment, which stop it alright, but create a nasty judder when coming to a complete stop. Having a look at them last night, it would seem that the front wheel might be slightly out of true: it rubs against the pad once or twice per wheel revolution.

Is this the likely cause?

Also, does anyone know if it is possible to replace the canti's altogether with some proper road brakes? I suspect not, given the frame limitations.

NB if you need to know, the canti's are Tektro Oryx which were supplied on the bike

George · Post by **George** » 06 Aug 2013 11:39

deero83 wrote:Is this the likely cause?

Irregularities in the rim are probably at least part of the cause. Play in the brake mechanism and/or the hub bearing can also cause juddery braking. Play in the headset can result in braking inducing a generalised judder.

deero83 wrote:Also, does anyone know if it is possible to replace the canti's altogether with some proper road brakes?

Depends on the clearances, but probably not. Probably better off truing wheel/adjusting brakes and, if that doesn't work, replacing wheel and/or brakes. When everything is working properly, you should have more braking power with your cantilevers, which is no bad thing on a winter/commuter/touring bike.

deero83 · Post by **deero83** » 06 Aug 2013 12:51

Have tightened the headset up as it was ever so slightly loose. Will see if that makes a difference.

Does it cost much to have wheels trued?

Ed Moss · Post by **Ed Moss** » 06 Aug 2013 13:47

Well it's going to be, er, "fun" mixing traditional and disc brakes on group rides

Philip Whiteman · Post by **Philip Whiteman** » 06 Aug 2013 14:02

Ed Moss wrote:Well it's going to be, er, "fun" mixing traditional and disc brakes on group rides

To extent you are right but within groups of people exclusively using rims, disparities may exist. The combination of various types of blocks with adhesion of rims produces varying brake co-efficients. As example, Koolstops are less efficient with American Classics compared to use with with Mavic SLs.

Your comment will of course orrect where cyclists using disk brakes with high co-efficiency produced by high quality pads powered by hydraulic application are then mixed with cyclists using wheels and brakes with a poor co-efficiency. Equally, users of cabled disks with poor adhesive surfaces may be less problematic when riding with block and rim users.

I once mixed brakes with different co-efficients within fleet of railway carriages, which produced exciting results and some big surprises for the footplate crew, guard and kitchen staff. But that is another story.