Using what brake levers?

I run it as a flat bar, with XTR hydros.

that Roubaix looks good but I can’t see past the hideous seatstays…

I run it as a flat bar, with XTR hydros.

Ah – so it’s a hybrid, not a road bike.

I don’t know why you feel the need for rolly eyes aracer can you not manage a civilsed debate without resorting to it?

anyway, I meant having the front tyre just at the point of losing adhesion

I meant having the front tyre just at the point of losing adhesion

How do you propose to manage that on tarmac?

It may have already been asked, but what is the advantage of disk brakes on a skinny tyred road bike other than a reduction in rim wear and possibly maintenance?

When it comes to braking performance, surely it’s the contact point of the tyres that is the limiting factor, not the brakes themselves??

Or am I missing something?

EDIT – Ignore me, delayed post. Just saw comments above. I’ll get me coat…

A disc in the wet is much better on the road IME – rim brakes tend to take a few metres to clear of water if it’s properly wet.

some sensible comments here

Ah – so it’s a hybrid, not a road bike.

that nugget. Fast enough to get the fastest descent of Kirkstone pass on Strava 8)

but what is the advantage of disk brakes on a skinny tyred road bike ….. when it comes to braking performance, surely it’s the contact point of the tyres that is the limiting factor, not the brakes themselves??

In my hilly part of the country the disc-brakes on my Kona Honky Inc (road bike) are much easier on the hands on twisty downhills than rim brakes when riding on the hoods. They just need a little bit of finger action 😯 on the lever to keep your speed in check. With the rim brakes I get an horrible pain in my hands after a while.

Other than that I don’t see any real advantage, for me, over rim brakes.

I meant having the front tyre just at the point of losing adhesion
How do you propose to manage that on tarmac?

Keep your weight back?

If you don’t have your weight right forwards, you shouldn’t go over the bars even with brakes full on – can skid the front wheel no problems assuming a good front brake. Obviously if your bars are super low, and your position is right forwards, it is harder to get your weight back, but you should be able to brake fully or more (ie. to the point the front wheel skids) without going over the bars.

In some ways it’s a skill worth learning – I emergency stopped so hard I did a front wheel skid at 70km/h once – I was trying to achieve a maximum speed during some pretty stupid road descent to a tight corner (at the bottom of Dyers Pass Road in Christchurch, NZ for anyone who knows it), and whilst the brief skid was scary, I’m sure as hell glad that I had the instinct to get my body back rather than putting myself over the bars at high speed.

If you don’t have your weight right forwards, you shouldn’t go over the bars even with brakes full on – can skid the front wheel no problems assuming a good front brake.

You must have some pretty rubbish tyres – that or very slippery roads. With a normal road bike position, even shoving your weight as far back as possible, the most you can manage before going over the bars is ~0.5g, which should easily be achievable with a decent road tyre.

http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics#Braking

th a normal road bike position, even shoving your weight as far back as possible, the most you can manage before going over the bars is ~0.5g, which should easily be achievable with a decent road tyre.

http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics#Braking

Hmm – looking at that, it seems that you’d have to have your centre of gravity below something between 50 and 60 degrees from the front wheel contact patch, which does seem unlikely. Although it only takes a slight change in coefficient of friction for that angle to change a fair bit. Possibly the times I’ve had it happen, it might have been slightly gritty or something.

‘I meant having the front tyre just at the point of losing adhesion’
How do you propose to manage that on tarmac?

It’s not that hard, I can briefly front-skid my road bike braking hard on calipers going downhill if it’s not perfectly dry, not a good thing to do but just to see how the bike / fork reacts. On a disc, modulation feels better so it’s more precise at / just before the skid point. (edit to add, not something that should happen in normal riding, just something I’ve done and that I noticed more control between hard braking and sliding point when using a disc)

That Spesh is gopping. See I don’t get the clean lines. Instead of a tiny caliper I see a long cable, a huge rotor, a hideous cast caliper and chunky hubs.

He’s right, of course: time trialing is the discipline where discs provide the least benefit and possibly the greatest drawbacks, primarily to aerodynamics. In fact, it seems unlikely that they would be adapted for TT’s at all.

I tend to agree with the oldgit, probably cause I am well on my way to being one myself.

In the wet on the hardest of descents I worry more about my tyres keeping me upright.

When it’s raining a lot and I find myself on some steep Valleys descent with a sharp bend or roundabout or something, I grab a handful of 105 and literally nothing happens for a good 10 yards. It’s very very sketchy, unnerving and dangerous. If/when I need to do an emergency stop I’m screwed.

Bring on discs.

Ford Pinto

That was a massive scandal and caused a huge debate and re-evaluation of the laws and moral issues, afaik. It’s not like it’s common manufacturing practice!

He’s right, of course: time trialing is the discipline where discs provide the least benefit and possibly the greatest drawbacks, primarily to aerodynamics. In fact, it seems unlikely that they would be adapted for TT’s at all.

which it could easily be argued applies to a vast percentage of road race scenarios, think incremental gains. What do you gain, what do you loose, what matters more?

And pros will use what they are paid to use. So just because pros use something doesn’t always mean they are the best solution. However if they were really crap then pros would refuse…

When it’s raining a lot and I find myself on some steep Valleys descent with a sharp bend or roundabout or something, I grab a handful of 105 and literally nothing happens for a good 10 yards. It’s very very sketchy, unnerving and dangerous. If/when I need to do an emergency stop I’m screwed.

But what you really want is to slow down without brakes, which ain’t going to happen. Not a nice feeling, it’s wet, you’re going fast downhill, the kerbs getting nearer. Powerful brakes are the last thing I need. What I want is dry tarmac under my tyres and not a film of water.

But what you really want is to slow down without brakes, which ain’t going to happen.

Dunno what you mean there.

As for tyres, there’s plenty of grip. If it’s just stopped raining and the road is wet, I have plenty of traction. I’d just like the option to try braking, rather than have nothing.

And pros will use what they are paid to use

I’ve no doubt that to some extent this is true, but no company is going to pay a pro-race team to start using something thats going to make them lose, and given races are won by fractions of a second, if theres even the slightest disadvantage to discs (other than price) we’ll see it…. once the UCI allow them that is.

Powerful brakes are the last thing I need.

how many times does it need saying… just because you’ve got discs it doesn’t mean you can do nothing other than lock up the wheel and fall off. I’m using discs on my road bike right now, what you’ve described never ever happens, and I was descending on an utterly rain soaked road at 35mph only this morning. Judging them purely as a means of slowing you down, they work better than rim brakes in EVERY situation. The (possible) downsides are due to weight, cost, stiffness of frames/forks, complexities, possible risks in crashes with lots of other riders etc….

Personally, i’m also unsure as to whether they are needed on race bikes, but I’d like to see what the companies can come up with if the UCI relaxes their restrictions.

As aracer says, well set up rim brakes have enough power to generate the maximum possible decceleration which happens just at the point where the back wheel is unweighted.

Having used discs on my Tripster for the last 18 months, the big advantage is predictability in the wet. I’ve had a few unnerving moments with wet rim brakes where there’s a delay of a few metres and then they can bite quite dramatically.

The advantages for road racing seem marginal at best. I think the reality is that manufacturers are keen to keep bike development going, so that they can keep the upgrade cycle going and sell more bikes. Bikes are such simple machines that after 200 years of development it is really very hard to find a change that makes any difference at all. Electric shifting is a case in point – by all accounts it’s very nice to use, but it’s not seriously going to make any difference to your performance (actually, I can seen the possibility of having multiple shift buttons being useful on TT bike on a hilly course, but that’s about it…)

That said, I look forward to the trickle down of improved disc technology on road bikes, as the combination of STIs + BB7s on my commuter isn’t a patch on a decent set of MTB hydraulics.

I’ve never ridden a pro level road bike, or indeed anything with Dura-Ace, so I wonder if more braking power would allow people to out-brake others on those long mountain descents?

That’s what I think pdw. I don’t think the market for road discs is being driven by the race fraternity, but by just about every other road bike group. And I think these other markets need to see discs on pro bikes which will give the marketing boys the green light.
I also can’t help think that the current demand for discs comes from the recent huge crossover of riders from the MTB world?

But what you really want is to slow down without brakes, which ain’t going to happen.

molgrips that feeling when you are just hanging on, when you can’t steer, you dare not brake or do anything but see it out.

Can I have one of these please?

Specialized will apparently have the Tarmac with the SRAM hydro discs mid year but it won’t be bolt-thru 135mm etc. Have to wait for 2014 for that.

We all know what the modulation is like with discs compared to rim brakes

Keep seeing this, I don’t quite understand. I borrowed a mates Spesh Allez with Sora groupset for a year or so and could do lovely twisted rolling endo’s (most efficient way of getting stopped and turned ready for the green at one particular turning. honest!) If that doesn’t demonstrate great modulation on bog-standard rim brakes, I don’t know what would.

Can’t do them as well on the BB7s on the new bike, they’re not smooth enough. Maybe it’s the discs, or the fact that the disc is pushed over by the moving pad into the fixed pad, exagerating the effect of the pattern in the disc. ?

molgrips that feeling when you are just hanging on, when you can’t steer, you dare not brake or do anything but see it out

If the road’s really slimy or something, perhaps. But I’m talking about when you are approaching a roundabout or hairpin bend, and you have to slow down and steer or find yourself eating bricks.

Surly the will be some discs in the tour this year? I hope to see at least 1 team running them.

Nothing will get up and running in the Pro tour until the support cars (including the Mavic neutral) can carry disk wheels and every rider can have confidence they can put any wheel in the back and the brakes won’t rub. Can’t see everyone wanting to get together to muck around shimming disks so they’ll fit into all bikes. There’s a lot more leeway on a rim brake.

CX Pros might use them more as it’s your own wheels you’ll be using.

A hydro rim brake like SRAM are supposedly doing might become the compromise for a while.

Nothing will get up and running in the Pro tour until the support cars (including the Mavic neutral) can carry disk wheels and every rider can have confidence they can put any wheel in the back and the brakes won’t rub. Can’t see everyone wanting to get together to muck around shimming disks so they’ll fit into all bikes. There’s a lot more leeway on a rim brake.

This is one of those innovations that will go from “entry level/grass-roots” up to pro cycling, not filter down.

The marketing for disc brakes will be aimed at commuters, enthusiasts, Sportive riders first. Mainly because at the moment, you’re not allowed to road race with disc brakes (UCI rules) so until that changes (which it will do within the next year or so), there’s really no point in aiming this at the pro peloton.

It’s a difficult situation at the moment, everyone is waiting for everyone else. Frame manufacturers want a standard; disc manufacturers want the frames to put their products on; couple that with factors such as cable/hydraulic hose routing, integration of existing shifter format (STI, ErgoPower) with the internals for hydraulic braking. Everyone is waiting to see the developments but it’s a catch 22.