Road hydraulic discs

As exciting as the new top end bling shown in the OP is, if Shimano/3rd party Hydraulic road discs are only just arriving as a Di2 only option now, I can still see more basic cable discs making the biggest initial running on the road bikes that real people can actually afford to buy, if Shimano don’t do a tiagra or 105 level cable operated caliper that can work with their existing STI units (like the BB7/BB5) then they are total mugs, and could easily lose a chunk of the market to SRAM…

I’d expect to see lots of Disc compatible frames, still with canti mounts in the next 18-24 moths to give people future upgrade options…

Out of interest are road bikes now adopting the 135mm spacing, post and/or IS mounts direct from MTBs or will they all decide to re-invent things all over again?

As for sustained alpine descents cooking a set of 140mm discs?
Well it might seem obvious to all of us armchair experts, but I suppose someone had to blaze the trail and write that article first, to be fair I don’t think He’s trying to de-bunk discs for the road, it is new terratory for many roadies and I don’t think all of the technical issues are fully appreciated…
He talked to manufacturers and I think it rounds up the challenges that they face quite well, in short they are going to have to try and make lighter brakes that can accomodate longer periods of heavy use, the point is made that bigger rotors and other cooling features will help, but ultimately there will also be a period of adjustment while road riders, generally not used to discs, need to adjust to their operation…

TandemJeremy – That disc brakes on tandems are dangerous …

Ooops 😉

(TJ – this ain’t a dig, I actually agree with you, and the above picture is essentially irrelevant, if superficially funny)

we need a caption competition to go with that pic….

stop eyeing up my arse!

cookeaa – new Shimano mechanical discs:

http://www.bikeradar.com/news/article/shimano-sora-and-tourney-2013-first-look-33204/

oh and yes 135mm spacing for road bike discs.

Reading this thread I do wonder how anyone gets up to 40 or 50 mph but then I remember I live in Suffolk it pretty flat here and long decents are several counties away. So from my perspective where the fastest you are ever going to go is about 35 mph (very breifly) around my way discs are pretty pointless as the short 35mph decent is always followed by a hill afterwards. Rim brakes are not history, I still use an MTB regulalry with canti’s and they are fine for Thetford.

For riding in the hilly areas I can sort of see the point but I do think take up will slow by club riders, certainly the clubs I know in Suffolk.

However having said all that, the Colnago in that link is a neat bike and I would have discs on a road bike over d12 which to me is completly pointless as I never get trouble with my cables or shifting and there is no battery to charge which I would forget to do.

As a mechanic that has worked in road racing my concern is wheel swaps in a race situation and the how easy it would be to swap a wheel when you have to negotiate how the caliper is mounted in relation to the new wheel and spacing etc. The whole 10/11 speed situation has already throw a curve ball into spares and speed in wheel swaps.

discs are pretty pointless

d12 which to me is completly pointless

Both already discussed at length…

disc brakes on tandems are dangerous.

That theory is debunked by practical experience.

After sintering some HS33s on our tandem bringing it to a stop from just 40mph and nearly sailing through a Give Way we went out and got discs (big ones) for ours and it’s the best thing we ever did for it. Never touch them to see how hot they’ve got though. ooyah

In the summer I saw some Americans on a tandem with a gargantuan disc on one end (I think it was back but can’t remeber, will have to see if I took a pic) and a V brake the other, which seemed like pretty strange decision making on the manufacturers part (or buyers if it was a custom build – either way they were matching F&f so presumably designed/built to go together).

There are braking issues with tandems you don’t tend to get with half-bikes, which explain Thorn’s stance on this – and having a V brake on the front along with a big disk on the back. The problem is that going down a hill a tandem will accelerate to a much faster speed, and have a lot more energy to dump in the brakes – therefore a lot of tandems actually tend to have 3 brakes, 2 normal ones and a drum brake. The drum brake is used as a drag brake going downhill to keep the speed down without overheating the main brakes. We’ve only ever had rim brakes on ours as I’ve always reckoned we don’t tend to carry as much load as some, and that I’m skilled enough not to need to drag a brake going down a hill – yet we once had a tyre blow off due to heat on a descent which wasn’t that long or steep, but was narrow and twisting and required keeping the speed down.

Discs seemed like an obvious replacement for the rim brakes and the drum drag brake resulting in less complication. The trouble is, even a big 203mm disk doesn’t have as much heat capacity as an old-fashioned drum brake. Therefore you are liable to overheat the braking system. It’s not rocket science here – you have twice the load on a tandem, yet people who would complain that a 140mm rear disc is too small seem to be happy using something smaller than 280mm on a tandem. This is the issue Thorn have with using disks – the fact they work OK for some people doesn’t mean there isn’t a potential issue if used by people who might otherwise have a drum.

The front V, rear disc is a Santana thing – you can read some of their argument for that at: http://www.precisiontandems.com/artdiscbk0.htm

Aracer – sorry but I disagree. we have cooked discs on our tandem but only in extreme conditions. Short steep downhills rolling slowly down using only one brake

thorns stance is based on a number of mistakes and only considers old tech. Part of the stance is no tandem rated suspension forks are available or tandem rated disc brakes – both just wrong in fact.

Personally I would never want a rim brake tandem – why not have the best available brakes?

That link you gave – this

Those reasons include the fact that due to the increased weight two riders exert on the rear wheel, it is virtually impossible to lock up the rear wheel under the most extreme braking- this makes it a wonderful location for such a smooth stopper. (After all, the braking power of an unarticulated V-brake-, one without a parallel-push mechanism-is already strong enough to lock up a tandems front wheel.)

Is nonsense – using the brakes properly it is far easier to lock the rear than the front. Using a big disc and loading the front wheel we can almost stoppie the bike and I can lock the rear easily. ON the other hand with proper application of the front brake ie loading it progressively its almost impossible to lock as the full weight of both of us is loaded onto the front tyre

The front brake is the most effective one. Its where you should have the best brake

sorry but I disagree. we have cooked discs on our tandem but only in extreme conditions. Short steep downhills rolling slowly down using only one brake

You disagree that it’s an issue for you, or that it’s an issue for anybody else? I’m not saying that Thorn are right, just that there is some logic behind their stance.

It’s also interesting that you disagree with it being an issue, then go on to give an example of where it is 🙄

That link you gave – this… Is nonsense

Not my words – hence how I phrased my intro to the link. You do have to bear in mind that Santana sold that on road bikes, so the situation is somewhat difference to your experiences off road. Or do you still think that everybody has the same requirements as you?

is a Santana thing

that’s what it was! I’m sure the rotor was bigger than 203 too, but that’s kinda explained in that piece too, without actually stating what size it is (unless I just got bored by that point 🙂 )

If it was my tandem (and I accept I have only ridden on a couple of times) I would want a big disk at the front for stopping power and an exqually big one at the back to avoid heat build up from dragging the brakes.

Not sure why you would want anything else really.

Not sure why you would want anything else really

A custom fork with equally big discs both sides?

EDIT oh yeah …and hub

A friend of mine had an offroad tandem just around the time disc’s where starting to become available, he claimed that on long descent’s the V brakes could get the rims hot enough to burst the inner tubes 😯
He ended up fitting the biggest discs hope made at the time and also had a V brake on the back operated by a thumb lever to use as a drag brake.

Edit: Is that tandem on the Quantocks?

Dibbs – yes – quantocks

Aracer its not an issue at all. We use out tandem on the road as well – its simply wrong to say its harder to lock the back wheel than the front- as you brake you transfer weight onto the front tyre.

the one we overheated was an old 4 pot – now run 6 tis which are more heat resistant – no issue with them

its not an issue at all for us

FTFY

its simply wrong to say its harder to lock the back wheel than the front

Good job nobody is saying that then.

the one we overheated was an old 4 pot – now run 6 tis which are more heat resistant – no issue with them

So you’re talking about problems with heat transfer to the fluid? Never heated up disk brakes enough on a descent to get brake fade? I have on twisty road descents in North Wales (when the chap I was riding with overheated his rims enough to blow the tyre), and on non-technical 3000ft off-road descents in the US. That’s running 160/140 discs when I was a skinny 65kg. I don’t suppose dual 203 discs provide anywhere near twice the amount of cooling or twice the resistance to heating the disc up enough to make the brakes fade. There are tandem crews more than 3 times that weight.

Never had fade other than boiling old fluid. Discs are blued from the heat – we do use sintered pads for that reason tho as they are more resistant to fade although they do transfer more heat to the callipers. big discs have a lot more surface area to loose heat from.

There is no issue at all with disc brakes on tandems if the right kit is specced – or anyway less issue than with rim brakes

Aracer that is what they ( in your link) are saying ( that its harder to lock the back) – if you have a decent stopper on the front you can transfer so much weight to the front tyre you get hardly any rear braking – and I can easily lock the rear on our tandem with the disc on it even with sticky tyres on the road and even without using the front for weight transfer.

i still can’t see why it shoukd be harder to change wheels!!!!

Oh yes sorry, shimano’s poor manufacturing.

big discs have a lot more surface area to loose heat from.

In pretty much direct proportion to their diameter. You have twice as much energy to dump on a tandem (for some crews 3 times the amount of potential energy I had). You don’t use discs which have twice the surface area (only about 30% more than even my little discs). The fact you’ve not had fading just suggests you’ve not encountered the conditions where it’s an issue. How many twisting steep tarmac descents in North Wales have you done? How many non-technical 3000ft descents?

that is what they ( in your link) are saying ( that its harder to lock the back)

I must be being dim then. Can you help me out by providing the direct quote from that link which suggests it’s harder to lock the back wheel than the front on a tandem?

Aracer – its that the brakes I use have plenty of heat resistance and ability to lose heat. Plus technique probably. I have put them under plenty of heat stress – including the4 worst situation – dragging down relativly steep hills relativly slowly – enough heat to blue the discs.
already quoted it. done both steep and tricky road descents and long offroad ones.

it is virtually impossible to lock up the rear wheel under the most extreme braking- this makes it a wonderful location for such a smooth stopper. (After all, the braking power of an unarticulated V-brake-, one without a parallel-push mechanism-is already strong enough to lock up a tandems front wheel.)

Fairy nuff on the Santana article – that is a load of BS. In my defence I have to point out that I’ve never suggested I agreed with that (in fact I disagree with an awful lot of the marketing stuff Santana have put out) – just that I’d not noticed that claim. After all, I’ve locked up the rear wheel on a tandem, and even endoed one!

Still disagree with you about the issue with disc brakes overheating and fading – if I’ve managed it with my little discs, then it seems very unlikely for it not to happen on a tandem with discs of only 30% more surface area. Maybe you’ve just not quite reached the point it’s an issue – you say long offroad, but 3000ft (that’s vertical)?

I have put plenty of heat stress into the brakes – the one time I really cooked the old brakes was only a couple of hundred feet descent – just it was slippy and I only had one working break so rolled down it slowly dragging the brake hard the combination of low speeds so less cooling and hard braking is what builds the heat – it can be done in very short distances. Our discs are blued and they often stink of hot brake

The ti six pots I now have are designed to cope with more heat – the pistons are perforated and TI and there is room for air to circulate between the pistons/ pads and body of the caliper – the pistons stand proud of the caliper even with new pads also a much bigger pad area and a sintered pad.

Yes done big descents on it in the highlands including with full camping kit and in massif central in France- if 1000+ ft won’t cook em 3000 will not. its low speed stuff that really cooks em IME and the thorn article suggests that as well.

I am absolutely confident that there would be no heat build up issue on alpine passes even with these brakes – unless I dragged them the whole way down at low speed

if 1000+ ft won’t cook em 3000 will not.

On the contrary – my brakes were fine until near the bottom of that.

As its easy to overheat a brake in a short distance if you put a lot of heat stress into it – I cooked the m4 in couple of hundred feet of slow dragging down a steep hill I would have expected them to have reached a steady state well before the bottom of a 3000 ft hill or have overheated much quicker.

Its just something that the brake designers will have to consider for road bikes – and the riders will have to lean not to drag them continuously.

Phenolic or Ti pistons, and airflow management ar ekey I guess. Maybe ventilated rotors like v2s?

and the riders will have to lean not to drag them continuously.

So there is a problem with the brakes then?

Not more so than rim brakes – appropriate technique for the kit. You have so much power there is no need to drag the brakes. You can let speed build and slow when needed.

Your mate blew a tyre with heat build up remember 🙂

The 6 pots I have are very good at dealing with heat – thats why I got them

Hydraulic disks on road frames seems to be trying to solve a problem that doesn’t exist and at the same time coming up with lots of engineering trade offs (heat dissipation versus weight).

For the pros they’d have a place and improve performance without the overheating issue as they’re featherweights and brake as little as possible.

The average mid life crisis buyer who’ll be able to afford them will be where the problem lies. To dissipate the heat generated from trying to stop the powerfully built will require a bigger disk and more weight. Trade off.

Cable disks is the obvious solution in terms of braking performance and reliability, but this doesn’t have the same desirability as hydraulics.
This is probably the reason why this has taken so long to come to market in any real sense. I’m sure they’ll find a way to market it though.

Not the whole “faster riders brake less” thing again?

NOOOOOOO!

And pros being a different species that weigh substantially less? Not really, and in any event compensated for by the height gain in their mountain rides.

So faster road riders brake more do they? right….

Average weight of pack of pro riders compared to average weight of pack of Sunday club run. Which one is higher in your opinion?

My Dawes Super Galaxy tandem has a drum brake on the rear for dragging purposes. It’s connected to an old gripshifter. These were originally designed for mopeds. This is from the age before disks. And yes, rims can easily get hot enough to burst tyres. I think disks have partially solved this problem.

Disks on road bikes surely only make sense for carbon rims, where I can accept that the combined weight could be less than rim and caliper (maybe). Hydraulic as opposed to cable doesn’t really make much sense to me.

fourbanger – Member
So faster road riders brake more do they? right….

Average weight of pack of pro riders compared to average weight of pack of Sunday club run. Which one is higher in your opinion?

Can you establish they brake significantly less?

Average pro – 60kg? Average club rider 75kg? 20% difference, easily within the margins of brake design.

I’m with cynic-al.

and even if the “ave” pro weighs 60kg, there are plenty who weigh over 80

^^^^

Thats before you factor in higher pro cycling speeds…..

My thought with disks is some joe public guy ants to make his new disk braked road bike lighter. Fairly simple, stick a set of 140mm disks on, jobs a good un.

Might not stop his 18st on a downhill during a sportif, but hey, his bike is now 100g lighter so it must be better. There’s nothing really he can do to rim brakes to make them lighter currently.

Hydraulic as opposed to cable doesn’t really make much sense to me.

It’s not JUST about the braking. As I’ve said before, this is about the cable runs and about making everything internal. Hydraulic hoses can be routed any which way you want with 180 degree bends and all sorts with no loss in performance. Everything routed through the tubes, no need to replace cables.

The sensible thing to do is combine hydraulic discs with electronic shifting and put all the gubbins into the lever. Makes all the lines very clean, gives consistent performance for years and the weight issue is neglible given that bikes can already be built way below the UCI weight limit of 6.8kg/15lb without a problem (other than cost).

this is about the cable runs and about making everything internal

Fair points for professional machines.

this is about the cable runs and about making everything internal

Totally agree and I think this is going to lead to the adoption of hose connectors so you can have a fluid filled hose/tube in the frame and just unplug the caliper and lever without the introduction of air to, or loss of fluid from, the system.

The adoption of discs on road bikes is going to push the development (or maybe that should be refinement) of little things, that we didn’t know we wanted/needed, that will make tasks like wheel swapping and replacing damaged levers quicker and easier IMHO – if changing wheels with discs turns out to be as time consuming as some seem to think it will it won’t take long for the teams to push their sponsors to improve it. I can see disc mount positioning on hubs to be one of the first things that get standardised, either that or quick and reliable caliper re-alignment.