FAO disk brake lovers...

veronese68

I must say I hadn't moticed the lugs either. I was blinded by the brakes. I also think the Volagi frame looks nicer when I look again with more blood circulating freely. If I was actually going to buy one I'd go Volagi. Good to see more road bikes with discs, I'm sure it's the future and they will only get better. This from a confirmed luddite (sometimes).

meanredspider

Sketchley wrote:

Look in the first link I posted, it goes in to some detail... I'd been interested it what Volagi say about it....

Pretty much the same as me I'd guess - the relative loacations of the caliper and the QR are totally different in the road set up than the MTB illustrated. If you imagine undoing the QR completely on the road bike and replacing the brake caliper with a fixed pin, you'll see that the vast majority of the forces act backwards. There will be some vertical component but it will be relatively tiny. The geometry shown in your link sees the vast majority of the forces generated acting vertically because of the relative postions of the QR and the caliper (almost horizontal). Not only that but the "lever arm" of the MTB is far worse too due to larger discs. Finally, the load applied is only the load that the tyre can generate - a 25c road tyre at 130psi can't generate the grip of a 2.1" MTB (dampered) tyre at 45psi.

Everything is working in the favour of the road bike

bails87

MRS: I wasn't saying that it was a significant or likely problem. Just saying why it, theoretically, could be.

As you know, I have the disc braked CX, and my MTB is obviously on discs. I have no worries about using them.

Barteos

...the load applied is only the load that the tyre can generate - a 25c road tyre at 130psi can't generate the grip of a 2.1" MTB (dampered) tyre at 45psi.

In normal conditions you can't skid a front road tyre on tarmac (you'll go over the bars first) but you can do this often with MTB tyres (off-road). Also road wheels will typically have slightly larger diameter and speeds involved are likely to be higher.

For those reasons front brakes on road bikes will be dealing with higher forces (and therefore (front)rotors should have the same or larger diameter as on MTBs for a given rider's weight)

meanredspider

Barteos wrote:

In normal conditions you can't skid a front road tyre on tarmac (you'll go over the bars first) but you can do this often with MTB tyres (off-road). Also road wheels will typically have slightly larger diameter and speeds involved are likely to be higher.

For those reasons front brakes on road bikes will be dealing with higher forces (and therefore (front)rotors should have the same or larger diameter as on MTBs for a given rider's weight)

The comparison with on-road and off-road isn't very enlightening. Plenty of MTBs get ridden on the road. With the introduction of 29ers, the wheel diameter is mute. I also think speed is a little mute too - either the tyre will give up grip or, as you suggest, the rider will be catapulted way below the different speeds. What is true, however, is that MTB are likely to be ridden down steeper gradients where the rider's weight has less of a positive impact on the situation.

Finally, practice just says road bikes have smaller rotors (probably for the reasons above). My Volagi has 160mm and the Cologno 140mm. My Cube Reaction has 180mm. Go figure

sketchley

Is the comparison not between road and MTB but between calliper and disc on a road bike? i.e. to get same breaking power as a calliper (judge to fine by most on a road bike) requires only small rotor?

bails87

meanredspider wrote:

Barteos wrote:

In normal conditions you can't skid a front road tyre on tarmac (you'll go over the bars first) but you can do this often with MTB tyres (off-road). Also road wheels will typically have slightly larger diameter and speeds involved are likely to be higher.

For those reasons front brakes on road bikes will be dealing with higher forces (and therefore (front)rotors should have the same or larger diameter as on MTBs for a given rider's weight)

The comparison with on-road and off-road isn't very enlightening. Plenty of MTBs get ridden on the road. With the introduction of 29ers, the wheel diameter is mute. I also think speed is a little mute too - either the tyre will give up grip or, as you suggest, the rider will be catapulted way below the different speeds. What is true, however, is that MTB are likely to be ridden down steeper gradients where the rider's weight has less of a positive impact on the situation.

Finally, practice just says road bikes have smaller rotors (probably for the reasons above). My Volagi has 160mm and the Cologno 140mm. My Cube Reaction has 180mm. Go figure

Agree with you (meanredspider) here.

Wheel size is probably a moot point, seeing as a the ISO size of a 26" wheel is 559, and a29"/700c is 622. Add a 25mm tyre onto a 622 wheel and the total diameter is 672mm. Add the width of a pretty typical 2.25" (57mm) tyre onto a 559 rim and the total is 673mm.....

The MTB tyre and wheel is actually bigger than the road tyre and wheel!

Also, geometry. Would an MTB allow you to get 'in' the bike rather than being perched on top of it? That would lower your centre of gravity, meaning you could brake harder on an MTB.

symo

It looks wrong, I just don't see the need for discs on the road. I have yet to have any problems wet or dry with conventional brakes at all. In fact I had more issues with my old commuter (now the GF's) disc brakes, squeling, clamping on, no pull, sloppy braking, having to bleed them, etc etc. Seriously the only time I have lost a tyre owing to heat build up was owing to some dipstick not being able to descend during a sportive, and centring himself in the road, forcing me and about 8 others to slow down fast as we could not pass.

anonymousblackfg

have a read of the bikerumor site, the guy their boiled his fluid in 3 minutes on a proper road desent removing all braking ability... the cooling solution is looking far more key than the worry about forces and where you mount the caliper...

UndercoverElephant

symo wrote:

It looks wrong, I just don't see the need for discs on the road. I have yet to have any problems wet or dry with conventional brakes at all. In fact I had more issues with my old commuter (now the GF's) disc brakes, squeling, clamping on, no pull, sloppy braking, having to bleed them, etc etc. Seriously the only time I have lost a tyre owing to heat build up was owing to some dipstick not being able to descend during a sportive, and centring himself in the road, forcing me and about 8 others to slow down fast as we could not pass.

The only real advantage I see is with carbon rims, I wouldn't like rim brakes too much with them.

Fat-Boy-Roubaix

What appeals to me is a light fast road bike that takes proper guards, the disc is an added bonus. Not sure on the c59 but the Volagi weighs in @ 17lbs.

Never ceases to amaze me that you are expected to run guards on club runs yet most road bikes you are lucky if you can get a set of cruds on there.

Also 80% of road bikes sold I would guess never get anywhere near a competive race, the Volagi appears to be the only "modern" looking carbon road bike that could be used almost all year for all purposes.

Barteos

While all the points (for smaller rotors on road bikes) are valid per se and it's true that the wheel size argument was a bit off, I still don't believe that the differences are so great that would justify reducing the rotor size for other than marketing reasons.

Popularity of certain standards ("practice" argument) doesn't necessarily prove that they make any sense whatsoever, 23mm tyres being the best example.

In my previous post I forgot to mention one more thing - the compromised ergonomics of road brake levers which have to be comfortable as an extension of the handlebar and at the same time to work reasonably well from various hand positions. Compare it to straight bar levers that can be set-up very precisely where you want them to be and operated from one position.

Aidy

anonymousblackfg wrote:

have a read of the bikerumor site, the guy their boiled his fluid in 3 minutes on a proper road desent removing all braking ability... the cooling solution is looking far more key than the worry about forces and where you mount the caliper...

Yeah, I was going to bring that up too.

I wonder if that's where the cooling fins have come from on the newer generation Shimano discs.

rick_chasey

Barteos wrote:

In my previous post I forgot to mention one more thing - the compromised ergonomics of road brake levers which have to be comfortable as an extension of the handlebar and at the same time to work reasonably well from various hand positions. Compare it to straight bar levers that can be set-up very precisely where you want them to be and operated from one position.

If you find stopping difficult on a road bike, either it's set up wrong, or you need to MTFU.

roger_merriman

Aidy wrote:

anonymousblackfg wrote:

have a read of the bikerumor site, the guy their boiled his fluid in 3 minutes on a proper road desent removing all braking ability... the cooling solution is looking far more key than the worry about forces and where you mount the caliper...

Yeah, I was going to bring that up too.

I wonder if that's where the cooling fins have come from on the newer generation Shimano discs.

something very wrong to overheat that quickly clearly like any brake system if it can't get rid of the heat you'll get problems though 3mins is remarkably quick, not entirely believably so even.

Aidy

symo wrote:

It looks wrong, I just don't see the need for discs on the road. I have yet to have any problems wet or dry with conventional brakes at all. In fact I had more issues with my old commuter (now the GF's) disc brakes, squeling, clamping on, no pull, sloppy braking, having to bleed them, etc etc. Seriously the only time I have lost a tyre owing to heat build up was owing to some dipstick not being able to descend during a sportive, and centring himself in the road, forcing me and about 8 others to slow down fast as we could not pass.

For me, as a commuter:

* My wheels can be any kind of true
* More consistant braking (discs don't get dragged through as much crap as rims)
* Not wearing out braking surfaces every year
* Much improved brake pad life
* No repositioning cables as brake pads wear
* More braking power does make sense if you're carrying panniers

That said, for a pure road bike, which isn't going to undergo commuting duties, I'm not convinced by discs yet.

Barteos

Rick Chasey wrote:

Barteos wrote:

In my previous post I forgot to mention one more thing - the compromised ergonomics of road brake levers which have to be comfortable as an extension of the handlebar and at the same time to work reasonably well from various hand positions. Compare it to straight bar levers that can be set-up very precisely where you want them to be and operated from one position.

If you find stopping difficult on a road bike, either it's set up wrong, or you need to MTFU.

That's obviously not what I said and my setup is perfectly good. All I'm saying is that flat bar levers are superior ergonomically to STI units (as brake levers) as they are designed ONLY for braking from one particular position and nothing else. STI units are a compromise.

Stevo_666

Nice bike (though not too sure about the paint job). I reckon we'll be seeing a lot more of these - disc brakes on road bikes are the way forward IMO. All you need now is some suspension for road bikes and the transformation will be complete ;-)

meanredspider

All I can say about discs on a road bike is don't knock it until you've tried it. Personally, I'm struggling to see the downsides. I don't (yet) see the point of hydraulic brakes on a road bike. BB7s work just great and need minimal maintenance. I'm very confident that this Colnago is just the first of a series of big names to bring out discs and, in time, discs will be the norm and we'll all think how quaint it was when bikes squeezed bits of rubber against the wheels to stop.

SimonAH

All I know is that that gives me a chub-on.

If you look at the NAHBB pictures you will see a huge increase in the use of discs and belt drives. Apart from pure race machines I reckon they are the way forward.

My next bike (when I get the cash together) will be a Ti copy of a Ritchie break-away (ish) with belt, hub gears and discs.

veronese68

SimonAH wrote:

My next bike (when I get the cash together) will be a Ti copy of a Ritchie break-away (ish) with belt, hub gears and discs.

Were money not an issue that would be my choice for an everyday bike. I'd just be terrified to leave it anywhere.

mcj78

Rick Chasey wrote:

If you find stopping difficult on a road bike, either it's set up wrong, or you need to MTFU.

Or it's raining

rick_chasey

mcj78 wrote:

Rick Chasey wrote:

If you find stopping difficult on a road bike, either it's set up wrong, or you need to MTFU.

Or it's raining

You'd think a nice stiff light road bike with proper tyres would stop quicker than some sloppy behemoth MTB .

Land Rover versus F1 car.

mcj78

Aidy wrote:

anonymousblackfg wrote:

have a read of the bikerumor site, the guy their boiled his fluid in 3 minutes on a proper road desent removing all braking ability... the cooling solution is looking far more key than the worry about forces and where you mount the caliper...

Yeah, I was going to bring that up too.

I wonder if that's where the cooling fins have come from on the newer generation Shimano discs.

Just posted on the review page re. this - the guy put together a superlight hydraulic cx setup via a cable-to-hydraulic actuator & even swapped out the original rotors for super-minimalist efforts, describing the setup himself as "perfect for ‘cross where speeds are low and braking is rarely a life or death matter" Then he pointed himself headfirst down a steep, twisty, tarmac mountain road - dragging his brakes all the way & even still doing 35mph! Are you honestly surprised he burnt out the discs & pads in a couple of minutes? Are you suggesting the same would have happened had he been on an MTB instead, or even if he'd used the manufacturer's own rotors? Of course not. The article tells me more about the current limitations of the human mind than the current limitations of discs on road bikes.

mcj78

Rick Chasey wrote:

You'd think a nice stiff light road bike with proper tyres would stop quicker than some sloppy behemoth MTB .

That's why baby Jesus invented hedges!

symo

Whats the increase in rotating mass owing to strapping to bits of metal rotating at high speed on the wheel too?

bails87

symo wrote:

Whats the increase in rotating mass owing to strapping to bits of metal rotating at high speed on the wheel too?

Probably about the same as the loss in rotating mass due to not having a braking surface.

And the rim is obviously further away than the brake rotor.

Edit: I've just built some wheels for the CX, using 29er mountain bike rims (Stan's Crest). They weigh 380g (actually, mine were a few grams under). Mavic Open Pros weigh 435g (according to Mavic).

On a new 'rim braking' rim, you've got a load of excess material, in the braking surface. Because the wheel is designed to be strong enough when it's at it's max wear point, so until you reach that, you're carrying excess baggage. And once you do reahc it, you have to replace the rim.

rick_chasey

bails87 wrote:

symo wrote:

Whats the increase in rotating mass owing to strapping to bits of metal rotating at high speed on the wheel too?

Probably about the same as the loss in rotating mass due to not having a braking surface.

And the rim is obviously further away than the brake rotor.

Surely the torque moment must be transmitted to the tyre through the wheel components: flanges, spokes, nipples, and rim spoke bed? You'd have to engineer for this moment which would inevitably lead to a heavier wheel.

supersonic

This may be of interest:

http://www.ne.jp/asahi/julesandjames/ho ... k_release/

Though I would say aerodyndamics are one reason for the position.

bails87

Rick Chasey wrote:

bails87 wrote:

symo wrote:

Whats the increase in rotating mass owing to strapping to bits of metal rotating at high speed on the wheel too?

Probably about the same as the loss in rotating mass due to not having a braking surface.

And the rim is obviously further away than the brake rotor.

Surely the torque moment must be transmitted to the tyre through the wheel components: flanges, spokes, nipples, and rim spoke bed? You'd have to for this moment which would inevitably lead to a heavier wheel.

Right, so you lose strength in one place, but have to put in somewhere else? Maybe?

My wheelset is tough enough for MTBing and weighs ~1590g. As a 'pulled out of the air' example, Fulcrum red metal 3s weigh 1800g and cost £400. Another £100 on top of what mine cost.