montanafan

Hello all,

I have had a Cannondale Cyclocross Disc for about 10 years now and just upgraded to a Specialized Roubaix Expert Disc. Both of these bikes are used for a 15 mile (one way) commute to work on pretty rough pavement. I love the performance and ease of disc brakes and am not going to go back to rim brakes.

When I went to pick up the Roubaix, I rode it down the block and thought, "Wow, these disc brakes suck!" They had maybe an eighth the power of the Avid BB5s on my C-Dale. Then it dawned on me that they were not yet bedded in. I have changed out my pads in cars, mountain bikes and my C-Dale, and all needed to properly bed in to get proper performance out of them.

This will happen normally within a week or so of riding, but you can also speed up the process by riding down a hill and apply significant pressure on the brakes to heat them up. Do this several times in a row. I like to go to a steeply tiered parking garage and run several trips down at speed.

If replacing pads, make SURE you clean your rotors first. Any contaminates on your rotors will bake into your pads and decrease your stopping power. Just google "bedding in disc brakes" and you will see lots of tips on this.

I am now back to easily doing nose wheelies with perfect modulation on the Roubaix. Things are great as expected.

I am posting this for those who may be test riding a new bike with disc brakes. If you feel that, "disc brakes suck!" because they feel like they don't have any power, just be aware of this. As disc brake road bikes are just starting to come to market with popularity, sales staff should advise this to buyers.

If you still feel, "disc brakes suck!" on a road bike for other reasons, well then just enjoy your rim brakes.

DX-MAN

True.

Now, any quality LBS SHOULD be telling customers that; it's the nature of the beast.

Maybe it's because I'm a Clyde who rides hard, but I left rim brakes behind years ago; even the 160mm discs don't do it for me. But BB7's w/ 185 rotors are 'butta'.

Replacement/upgrade parts can make a lot of difference, too; before they stopped making them, I ran XTR cables with my BB7's (and ceramic pads -- YESSS!), and the feel of the brakes was jewel-like flawless. I'm hoping the non-group "SP-41" cableset can duplicate that, they're on my list. Jagwire just doesn't cut it.

Anyone who disses dics without the full experience is just being foolish.

fietsbob

LBS here offers a 6 month as often as the need arises after sale, service period , and the bedding in
break in period owner behavior Recc, is part of the new bike speil .

cyccommute 

Disc brakes don't suck...rim brakes are, in fact, disc brakes...it's just that they aren't as much of an improvement as everyone tout them to be. A hub disc equipped bike doesn't stop any any shorter distance than a rim brake equipped bike if both systems have been properly set up.

I am also a clyde who rides hard. I do have "full experience" with discs as well as with rim brakes, I mountain biked many years on cantilevers, then many years on linear and many years on disc. I do fully loaded bicycle tours...me, bike and touring load are probably dragging 300 lb...through all kinds of terrrain including fast steep descents on steep mountain roads in rain. In none of my experience has the a hub mounted disc brake made much difference. I can ride just as fast downhill and stop with just the same amount of lever force with any brake system I have...disc, linear or cantilever.

Brakes are more about how they are used than the mechanism.

dynaryder

No they're not. I'm curious as to why you keep making this statement. Disc brakes are mounted at the hub,and the rotor is independent from the wheel. Rim brakes are mounted at the rim and use the wheel's sides for their braking surface. Disc brake calipers are rigidly mounted,all rim brake calipers move. Rim brakes require the wheels to be perfectly true for maximum efficiency,discs don't care.

A disc rotor looks nothing like a wheel rim.

I'd argue that they do. I switched to discs for commuting after my V's packed up with snow and caused me to glance off a car. I'll never use rim brakes in the snow. Also note,while under more normal riding conditions discs don't work any better,they still don't need the rims to be perfectly true,the pads last longer(and unless cartridge pads are used,are easier to change),are easier to set up,and don't cause any wear to the rims.

Bike Gremlin

Disc brakes are a bit more consistent in performanse when riding in rain and mud. Rim brakes are more affected with rain. For riding in hilly terrain on rainy days, if route requires regular braking and slowing down - disc brakes are a lot better solution. For most other things, rim brakes are simpler and cheaper solution IMO.

fietsbob

Technically you have a caliper that, when force is applied, squeezes something between it, that is circular.

Darth Lefty 

I haven't ridden a lot of disk brake bikes but here's my experience... my BIL's mountain bike with an upgraded front brake stops like a wall, but the Paris Velib bikes were as squishy as any I've ever used. So clearly there's plenty of variation.

hybridbkrdr

I wouldn't say they suck but if I did hesitate to buy a bike with disc brakes (or build one), it's partly because I read once someone saying his disc brakes seized after not riding his bike for a long while then the pic of someone's finger after he worked on his disc brakes.

dynaryder

No they're not.

discs:



hoop:


Big difference.

But in practice,if you were to squeeze a rim hard enough,it would deform. Pinched hard enough,you could actually get the bead to unseat,or even crush the rim. Disc rotors can,for all intents,be squeezed as hard as you want.

The Velib bike's don't have discs,they have drum brakes.

That's silly. If you don't take care of a bike,all kinds of bad things can go wrong. Ditto if you're not careful when working on anything mechanical. You want to talk dangerous,I used to work on F-4 Phantoms. Still have a scar on my lower back.

Everyone talks about how magical steel is. Do you have a frame or fork made of steel? I've got two friends who had steel forks fail in a short time from normal street riding. Heck,Salsa just had a recall on a batch of steel forks. Will this stop you from owning a steel fork?

Darth Lefty 

I see... I misunderstood what I was looking at before. Thanks.

cyccommute 

Let's get rid of the compact disc since it has no bearing on the discussion.

Now look at the hub mounted disc rotor. It is made from a flat steel round that has been relieved to save weight. But the only part of the rotor that you need is the part that the brake pad contacts and the part that connects it to the hub. The spokes connecting them are no different from the spokes of a wheel. You could even thin them down to the point where they were wires. You'd need more of them and someway to resist twisting but then you'd just have a small sized wheel.

The braking surface of a rim brake is exactly the same as the braking surface of a rotor. It's a spinning metal disc that is clamped between two friction pads. With mechanical disc, only one pad moves while a hydraulic (usually) moves both pads towards the rotor which is the way that all rim brakes work.

A hoop is still a disc of metal. It's just missing the middle bit.

UnfilteredDregs

and that explains why rim brakes are used across such a wide and disparate sector of vehicles, industries, etc..

DX-MAN

I knew you were gonna chime in with this, I've seen it before. In YOUR EXPERIENCE, discs are no better; in mine, they are a MAGNITUDE better. As long as you express yourself from the opinion standpoint, no big deal. But you like to present this as fact, when it ISN'T.

A set of Avid SD V-brakes WILL outperform a Pro-Max disc, every single time; but if you have a set of SD's that are outperforming BB7's, you have set up the BB7's wrong. And it's not a "style" thing that has converted the majority of MTB'ing to discs, but superior performance. Hell, XTR is straight hydro now!

Oh, I missed this...300-lb touring? I top 300# on a grocery run. COMMUTES are @ about 290.....

cyccommute 

Have you ever tried to crush a rim? As part of our disposal process at my local coop, we crush them and break them into little pieces. You have to put an aluminum rim in a vice and have to apply significant amount of force to even bend the walls in slightly. Don't forget that a rim is part of a pressure vessel that can hold a lot of air pressure. Given that the human hand can generated only about 20 pounds of force, I doubt that you could crush the rim with your hand even taking into account the increase in force generated by the lever.

Even with a disc brake on a bike, the limiting factor on brake force is the amount of force that can be generated before the bike pitches a single rider over the bars. You can generate a whole lot more force on the brakes with a tandem and you don't hear about a lot of rim crushing from tandem riders.

cyccommute 

I have (or have had) Tektro discs (crap), Avid BB7 (several of them) and Avid Juicy 7 hydraulics. I have (or have had) Avid Arch Rival, Shimano XT V brakes (squeally), Onza cantilever, various Shimano cantilever, Paul's Cantilevers, a few Avid SD brakes, and a few other generic rim brakes. The Avid BB7 are on the same level as any quality cantilever or linear brake I've ever used. Not superior but just the same. I even have a bike that has a BB7 front and an Arch Rival on the rear. It stops with exactly the same hand force and distance as a bike that is equipped with BB7 front and rear.

That's in the worst off-road conditions. On road, braking isn't nearly as demanding.

AusTexMurf

Understood what you were talking about from the beginning......
Agreed.

montanafan

I didn't intend this to turn into a debate on discs, just wanted to post some "experience" with them. My commute includes 5 miles of steep grade downhill in traffic, speed 30-50mph. No fade/overheat ever experienced. The modulation is more important than the ability to lock them up. Again, 10 years of commuting with the discs and they work for me.

The main purpose of the post was to warn of an inadequate braking feel on a test ride due to not being bedded in.

cyccommute 

I can hit 45 mph (without a tailwind) in the ~0.75 miles from the front door of my office to the front gate. I've done that for 30+ years without any fade or overheating of my rims in all that time. In fact, I've never overheated a rim in 35+ years of riding including mountain touring on a load touring bike as well as mountain riding on a tandem pulling a trailer. It's not about the brakes but how you use them.

And if any brake feels inadequate on a test ride the problem is with the set up, not with the brakes not being bedded in. All of my disc equipped bikes have worked fine out of the box if they were set up properly

alan s 

I'd much rather ride down a steep hill with disc brakes, than rim brakes. No question about it.

spare_wheel

to stir things up even further. i consider rim brakes and mechanical disc brakes to be inferior technology. decent hydraulics offer better modulation, more power, easier set up, and less adjustment.

mconlonx

When I ride my V-brake commuter, I've never had the thought, "Gee, I wish I had disk brakes." Except when a wheel is out of true...

When I ride my disc brake commuter, I've never had the thought, "Gee, I wish I had rim brakes." Except when I hear a pad rubbing a disk intermittently.

However, there have been canti brakes where I've thought, "Wow, I wish I had V- or disc brakes." And a current rear U-brake setup where I've thought, "Woah, even cantis are better..."

DX-MAN

Once again -- YOUR experience, not established fact.

DX-MAN

Sure, give ya that one in a second -- for the best part of $200 a wheel. The only real difference in experience is, mechanicals don't need to be BLED.

dynaryder

Yes it does. It shows what a disc is. A wheel rim is not a disc. Discs are flat. A wheel rim is a hoop.

When you were a kid,you used to hammer the square peg into the round hole,didn't you?

Wheel rims are not discs. I've no idea why you insist on saying they are. And I've no idea what bearing it would be on a disc vs rim conversation if they were considered discs.