Veloce brakes

[Jezrant]

Yes, 2007, so not what I'm talking about.

When Campagnolo introduced the dual pivot brakes in the early 1990s, they were dual pivot front and rear. Then sometime in the next decade they decided to shave off a few grams with the single pivot rear. Now they appear to be going back to the original idea with a dual pivot rear option on the higher ranges and standard on the lower groups.

Campagnolo has had lots of strange and interesting designs like the mono planers and the Deltas. I suspect the differential rear will end up like them. Why would you want a weaker brake in the back? If anywhere, I would have thought the front makes more sense.

[Mick F]

Why would you want a weaker brake in the back? If anywhere, I would have thought the front makes more sense.

I mentioned this earlier.

The SP brake has long arms, so although it's not as powerful as a DP brake, it's still more than adequate. I love the D brakes - my second set - because you can squeeze nice and hard on both levers without much danger of skidding the rear end. You can of course, but it needs much more squeezing.

The idea - and reckon it's true - that you squeeze the brake levers with the same force. With DP brakes at the rear, you have to be careful to "feather" the brake so the rear wheel doesn't lock up.

DP callipers are powerful items, and having one on the back may cause a problem. Think of a car: the rear brakes are weak, and the fronts are strong.

Any road up, this is all very debatable for bikes, and I'm sure this subject will run and run. I for one have stated my case for why I like D brakes.

[Brucey]

Why would you want a weaker brake in the back? If anywhere, I would have thought the front makes more sense.

not so. Weight transfer with high COG/short wheelbase vehicles limits the potential for the rear brake to do anything much. Motorcycle racers often barely use the rear brake at all. When there is no weight on that wheel, you can't brake using it.

If you can do a 'stoppie' using the front brake (most solos if the front brake is powerful enough), then in terms of slowing down as quickly as possible in the dry, the rear brake is useless. Note that if it doesn't modulate well, you may just lock it up when braking at 3/4 of maximum.

Rear brake use is mainly for cadence braking, confidence braking (you can 'test' for grip and often get away with a small rear lock-up) and stability. A brake that isn't too powerful but modulates well is probably a good brake for this purpose.

A DP rear caliper is probably reduced in power by the crummy cables/cable setup that most bikes 'enjoy'.

BTW I still run short reach single pivot calipers on my roadbike front and rear. They are more than powerful enough for me, and they are significantly lighter than DPs. In fact I removed brand-new Ultegra DPs to fit the single pivots. With slightly deeper drop calipers, I'd need more MA, and use DPs I expect.

cheers

[Mick F]

If you can do a 'stoppie' using the front brake (most solos if the front brake is powerful enough), then in terms of slowing down as quickly as possible in the dry, the rear brake is useless.

Not that old chestnut!

Have you been reading Sheldon Brown?
He says that as well.

I disagree entirely.

The rear brake is NOT useless in an emergency stop.

Try it.
Do an experiment.
I did, and published my findings on here.
Search for it if you want.

[Brucey]

If you can do a 'stoppie' using the front brake (most solos if the front brake is powerful enough), then in terms of slowing down as quickly as possible in the dry, the rear brake is useless.

Not that old chestnut!

Have you been reading Sheldon Brown?
He says that as well.

I disagree entirely.

The rear brake is NOT useless in an emergency stop.

Try it.
Do an experiment.
I did, and published my findings on here.
Search for it if you want.

I couldn't give a monkey's what SB says on this topic, I speak from personal experience.

Now; you may not be able to do a stoppie, for all kinds of reasons (bike and/or rider). The bike may not be capable of doing a stoppie promptly, if at all, in which case the rear brake would be able to improve matters slightly. Even if the brakes and the weight distribution are optimised, exploiting the full power of brakes on any vehicle is not easy; I would be quite surprised if you (or me, or anyone else) were able to do it without a lot of practice.

If you are a 'real racer' -or, on the road, 'complete nut job'- you might be able to wring the last bit of performance out of your bike, motorcycle, or car. If you want to try a meaningful experiment, try (say) braking as hard as possible using the vehicle of your choice, then give it to such a nut job/racer. They will (provided nothing actually breaks that is) be able to stop more quickly than you do, every time, guaranteed. The only way you get that good is practice, and lots of it, preferably not on the public highway. Arguably if you haven't thrown yourself over the handlebars a few times on the brakes, either your brakes are not powerful enough (unless you did lock the front, in which case you can't do a stoppie... see my earlier comment...) or more likely you haven't been trying hard enough, and don't really know where the limit is. A lot of braking systems (even if they can just scrape a stoppie, mid-braking) don't have enough immediate bite to render the rear brake completely useless BTW.

I've driven cars and motorcycles round racetracks and had the chance to observe others (including professional drivers) drive the same vehicles. There are numerous differences, but one of the big ones is usually how hard you are able to brake. It takes guts and practice to slam the brakes on to 100% instantly, when you know that 101% will see you off the track just as quickly. I could get close in a car, but on a motorbike my self-preservation instinct prevented me from getting anywhere near the limit on a regular basis.

If I was testing bicycle brakes to the absolute limit on a stoppie-capable bike, I'd want to be wearing leathers and a motorbike helmet. I'd expect to fall off about 1/3rd of the time. More than that until I got good at it, I expect.

cheers

[Mick F]

Ok Brucey!
I entirely agree with you ....... and SB.

In the real world on a real bike in a real situation, the rear brake will obviously grip and lock the rear wheel as you say. However, just as you jam both brakes on as hard as you can, the rear wheel will start to lock up - not suddenly lock up, and as it does it will contribute to the slowing of the bike. You can stop in a shorter distance by using both brakes. Not much shorter, but definitely shorter none-the-less.

Perhaps if brakes were 100% effective instantly - like jamming a broom handle through the spokes of both wheels - the wheels would instantly lock up. Real brakes are not like that, and retardation occurs over a finite time.

Also, frame geometry and centre of gravity come into this. I maintain that I have more weight aft than other folk, and I have an innate ability to shift my weight further rearwards when I brake hard.

[Jezrant]

Ok, you have me intrigued. Since we all agree that the dual pivot brakes have more stopping power than the single pivot, I still don't see why anyone really would prefer to have the single pivot on the rear except for maybe some demented pro racers. The dual pivots also modulate nicely, and it doesn't take a whole lot of practice by an ordinary recreational rider to avoid locking up the rear wheel. The single pivot rear just seems like a gimmick Campagnolo came up with to make their brakes look different from Shimano and the rest of the competition.

[Mick F]

Cars have weaker brakes at the rear.
Why?

[Jezrant]

ummm, cars have like a ton of metal under the bonnet.

[Jezrant]

never mind, you enjoy your single pivot rear brakes and I'll enjoy my dual pivots. No need to discuss further.
cheers!

[Mick F]

If you had the same brakes front and rear, you would need to make a conscious effort not to pull both brakes the same. Yes, we "learn" how to do this and it becomes second nature and is therefore done sub-consciously.

I reckon that by having a less efficient brake at the rear, it negates the need to pull less on the lever, so you can pull the same on both.

It may be a gimmick, but I like it.

[Mick F]

PS

When I modernised my bike in 2004, I fitted a Mirage groupset which included DP both front and rear. It was in 2007 that I upgraded to Chorus and opted for the D system.

Therefore I've tried both, and prefer DP/SP rather than DP/DP.

Have you tried both?

[Brucey]

I still don't see why anyone really would prefer to have the single pivot on the rear except for maybe some demented pro racers.

maybe you missed it before; SP brakes are -or can be- lighter. Only one pivot bolt, y'see.

Don't need the power of a DP brake at the back? Why have the weight then?

cheers

[Mick F]

Ha Ha!
Weight difference for Athena:
DP/DP is 331g
DP/SP is 306g

I weigh nearly 13st and my bike weighs 23lbs.
I hardly think 25g - 0.9oz - will make much difference!

[Brucey]

every mickle makes a muckle....

[edit; by which I mean; If you made 'heavier-its-only-a-bit-it-won't-make-any-difference' choices through every part of your bike and I made similar ones with my bike, my bike would weigh about 1.7lbs less by the end of the process.

Realistically this could be the primary differentiator between two new bikes with about £1000 difference in price.]

cheers