Most powerful brakes for Summer riding

[fignon1989]

Ok so here is my two pennies worth...........

I have / have had bikes fitted with canties, V-brakes, HS33,s and disks.

In dry summer conditions all of the above work well.

If you encounter mud or rain disks are in my opinion immeasurably better............

 

[Mike Muz]

Seen some stuff like that before on some custom chopper style bike, they look really cool

Buell Firebolts and Lightnings (optional) came with single sided perimeter rotor disk brakes. The one in the post above is a modded dual disk set-up by someone at Barber Racing.

Seem to remember the Elf Grand Prix 500 bikes using them too . Dunno what Rocket Ron was thinking when he signed for them ! :facepalm:

 

[cce]

disc brakes have a far larger contact area than rim brakes.

Care to share/expound on the math you're basing that on?

The face of a disc brake pad is larger than a rim brake pad.

 

[M-Power]

Each set up has its pros and cons. Always been a fan of the 89/90 XT cables, yokes and cantis. Set up properly with good pads ( Azteks ) its so light, modulates well and can lock the front wheel if needed. Easy to adjust repair out on the trail miles from home should you have an off.

 

[GSB]

My understanding is this. Braking by any method is an energy conversion from kinetic energy to thermal. We turn speed into heat. Rim braking makes use of a surface that's already there so its simple, and most importantly, light. It also removes the need for the hub and spokes to resist any huge torque loadings, since braking force is applies directly to the rim. This means you can go even lighter on your hub / spoke build. However, rim braking is compromised by some key points;

1/ an inability to sustain even medium temperatures. The limiting factor here is one of materials. The thermal mass into which you are trying to absorb the heat generated is made of a material that has a relatively low melting point, is softened by low temperatures, and is in direct contact with your tyres. This limits the amount of heat you can put in quite dramatically. So, whilst rim braking works fine in the city, on level trails, etc (and has done since the invention of the bicycle), it's quickly overcome by a decent downhill section.

2/ inconsistentcy of coefficient of friction. What you really really want is good brakes that work the same way every time you apply them. Hot or cold wet or dry you just want reliable dependable braking. Disc brakes, with a pad and rotor interface that can operate at high temperatures, located in an area away from most mud and filth, are far better at at delivering reliable, repeatable performance than rim brakes, which are routinely exposed to all manner of contamination that alters the level of friction from one puddle to the next.

Discs have their limitations too;

They are heavy lumps of unsprung weight. Weight weenies will always prefer rim braking for this reason. Disc braking will never be a match on weight terms for rim brakes.

They require stronger hubs, spokes, and forks than is necessary on rim brakes, which add further weight.

They apply forces much closer to the centre of the wheel, which means they have a reduced mechanical advantage. Lighter discs are usually smaller, and thus less effective, but larger discs come with a weight penalty. The huge discs on the motorbikes shown above look to me to be an exercise in styling rather than common sense, all I see is a massive increase in unsprung weight.

They are subject (as above) to the demands of fashion. The key is to choose the right sized disc and caliper for your body mass and riding style. Bigger is not necessarily better, but bigger is what we tend to get. Since the increase in size comes at the price of unsprung rotating mass, it can be a disadvantage to go to big. If you don't need it, you can stick with those minuscule polo mint discs and still enjoy the benefits over rim braking.

Overall, I see discs as the best choice for almost all applications now. They offer consistency, reliability, and can cope with all manner of abuse. The only time I would chose the poorer performance of rim braking now was if the weight was critical. And if weight were that critical, I'd probably look to lose the weight from the porky pie eating bastard in the saddle rather than downgrade the performance of my stoppers.

 

[FluffyChicken]

Weight an issue?
Hubs are already beefy to cope with the loads suspension can put through the axle.
There is little difference between the extra holes or threads needed by the disc attachment.

How much lighter in real terms are callipers/rotars and bolts than a canti/hyrdro setup incl bolts..

A disc tab must be lighter than canti bosses especially as they be carbon/alu setups.

Are the frames/forks lighter as they only need to design around the tab area and not the whole length of the stays/fork brace ?

The rims now do not have to be over bulky to include a braking surface, you can now design light and interesting rims.

 

[halaburt]

disc brakes have a far larger contact area than rim brakes.

Care to share/expound on the math you're basing that on?

The face of a disc brake pad is larger than a rim brake pad.

I think you mean WIDTH. By my measurements of a few samples, disc brake pads are about 14mm wide whereas rim brake pads are about 8mm.

But then, if you're focused only on the pad, there's also LENGTH. Again, from a few samples I measure about 29mm for disc pads and rim pads ranging from 57 to 79mm. By my math that makes the pad surface AREA of rim brakes 10 to 50% larger than that of discs.

I would then suggest that the brake surface area of the disc or rim is at least as important as the pad's surface area. Here's some math on that:

A few notes on these calculations:
- For brake surface diameter on rims I used the 4mm less the the BSD (based on measuring a few rims)
- The 8mm rim brake pad width was based on measuring several samples (WTB Speedmaster, Kool-Stop MTB, Kool-Stop ThinLine)
- The 14mm disc brake pad width was based on measuring pads for a Shimano M970 XTR brake.

So: Rim brakes have a slightly larger pad working on a brake surface roughly DOUBLE that of discs. Now I'm not saying that any of this makes them better or definitively answers the OP's question... but wanted to correct your point about contact area.

 

[scant]

Would hydraulic bakes theoretically be more powerful than V or cantis ? Never tried but I would assume it takes less lever pressure to slow down using hydraulics .

basically yes, regardless of conditions modern hydraulic disc brakes are significantly more powerful than any cable brake, V,canti, rollercam or whatever.

 

[cherrybomb]

I think you mean WIDTH. By my measurements of a few samples, disc brake pads are about 14mm wide whereas rim brake pads are about 8mm.

But then, if you're focused only on the pad, there's also LENGTH. Again, from a few samples I measure about 29mm for disc pads and rim pads ranging from 57 to 79mm. By my math that makes the pad surface AREA of rim brakes 10 to 50% larger than that of discs.

I would then suggest that the brake surface area of the disc or rim is at least as important as the pad's surface area. Here's some math on that:

A few notes on these calculations:
- For brake surface diameter on rims I used the 4mm less the the BSD (based on measuring a few rims)
- The 8mm rim brake pad width was based on measuring several samples (WTB Speedmaster, Kool-Stop MTB, Kool-Stop ThinLine)
- The 14mm disc brake pad width was based on measuring pads for a Shimano M970 XTR brake.

So: Rim brakes have a slightly larger pad working on a brake surface roughly DOUBLE that of discs. Now I'm not saying that any of this makes them better or definitively answers the OP's question... but wanted to correct your point about contact area.

It's not as simple as that.

Its about the ability to dissipate heat. Disk brakes are significantly better at absorbing and dissipating heat than rim brakes.

Size does matter , but only in as much as it effects the above.

 

[legrandefromage]

Depends on the caliper too, had some that just didnt work (Coda) and had to replace many with plastic, ahem, 'composite' pistons that seized.

Hydraulics are great but then I dont need to get a lift up to use them riding down yet so I'll stick with cantilevers and dual pivots because thats all I have these days.