Maelochs

Careful and sensible moderation much appreciated. A thread like this could get really ugly really quickly ....




if I jumped in.

Oneder

At the end of the day carbon fiber is just very fancy plastic, and its fiber reinforcement is mainly in one direction not all around. A few minor collisions or dings and it can become totally worthless. A carbon fork on a road bike toy, whatever. Putting one on a mountain bike is an exercise in silliness, so no big surprise if you go through carbon forks easily that way.

superpletch

i cant believe that bike mfg's with all their resources would produce a bike that would be so dangerous that forks and frames a cracking with regularity and grandmas and not very good riders are flipping over the handlebars causing death and destruction!!!!

maybe put down the physics book and go for a ride. I tell all my children.......practice, practice, practice

cyccommute 

Yes, there is reason to deny it, because it isn't true. Your explanation is wrong.

On the other hand, if you are going to "put out your arm to break your fall" all you are going to do is to break your arm. "Bracing for impact", "catching yourself in a fall", "putting out an arm", etc. are all wrong responses to crashes of any kind...very wrong.

We'll just have to disagree. As I've said, I have brakes of all different flavors and not one of them is "inherently" stronger than the others. I have a bike with a disc on the front and v-brakes on the rear and there is no difference in the pressure I have to use on the lever to actuate the brakes. I don't have to be more delicate with the front nor do I have to pull stronger on the rear.

I'm also not more cautious about the bikes with disc brakes vs bikes with rim brakes. I use the brakes the same way independent of where the caliper is mounted. And every disc brake equipped bike I own runs 203mm rotors on the front.

Which brings us to a different issue all together. I think we can agree that this quote from BikeRadarUSA is pretty much accepted wisdom

A rim brake is no different in function nor physics than a hub mounted disc brake. They are both "disc" brakes in that they clamp onto a spinning disc of metal to stop the bike. You can think of a rim brake as just a giant rotor...a 622mm rotor. There are differences, of course, but those are related to the pad material rather then the mechanism. A similar pad material on a rim brake would make for an almost unusable amount of braking power. Even with rubber pads, it is still possible to flip a bike with rim brakes. That's why we all run our brakes with the front brake on the left. It was even possible to flip a bike with rim brakes back when most brakes worked incredibly poorly.

I'm no fan of discs. They have various aspects that I don't like nor do I think they are all that necessary. People use them because they haven't learned to use their brakes effectively to begin with. But I don't consider them "unsafe".

Slightspeed

I have carbon bikes, aluminum, steel bikes, rim brakes, disc brakes, bar ends, down tube, indexed Sti, Di2, it's all good. Buy what you want, ride what you buy, just shut up and ride.

rydabent

I turn 80 this year. It would seem that an old coot like me would be the one against discs. But im not, in fact I highly approve of disc brakes.

How ever it seems the cycling community is full of old fudds that just wont accept anything new. At my age I remember the resistance to clipless pedals and click shifting. Now it is disc brakes.

People against I am afraid are fighting a losing battle. The two things that make discs better is they ARE a better brake in all kinds of weather, and they do not scab up and wear out expensive rims. And lastly mfg like economies of scale that make discs a better deal if they can put them on all kinds of bikes.

Lazyass

I saw a carbon disc bike explode when the rider hit the brakes. It's as if the brake lever was a detonator on an atom bomb. It just blew up. So beware.

jefnvk

So, you're telling me that I am going to have a much harder time getting my bike through airport security???

Lazyass

Yeah, pretty much. I read that terrorist groups are looking to use carbon disc bikes for attacks. Go about 30mph, grab the brakes and.... boom.

Canker

Carbon rigid forks are rather common in the mtb world.

Oneder

I know they are common, I am not sure it makes much sense for amateurs though. This guy's story is not surprising to me, though it is to others for some reason.

asmac

Those are called hoops. You have hoop brakes.

bruce19

I haven't read all the posts so if what I say is redundant...apologies. I have rim brakes on my road bikes and mechanical disks on my CX bike. IMO, the modulation, feel and stopping power of discs is demonstrably better. I have no major issues with rim brakes but discs are just better. Just one man's opinion.

IronM

I have disc on my MTB and gravel bike - love them!

I'm finally leaving road racing (masters), and l and am casually looking around to replace my race rig with a disc road bike, just for kicking around. If it weighs a bit more - OK, whatever. I weigh more too. I find disc brakes just work fantastic. I know they may not 'pro', but neither is my saddlebag & blinking rear light; so...

TKunich

We can always tell the people who ride and those that don't. They always assume that they are the one's knowledgeable. Before actually making really stupid statements they would just google CF failures.

Today on a 50 miler a guy who was really pushing the pace almost fainted when we rode about 200 yards on hardpack trail WITH ROAD BIKES YIKES.

superpletch

from someone who rides daily on carbon, steel, road, gravel and single track with disc and rim brakes i find you so wise that you can use google. i bet you rant on twitter too. i'm impressed.

another thing I teach all my children, don't believe most of what you read on the internet.

indyfabz

Wut

Maelochs

So ... the zombie ghost of asploding carbon fiber has returned. Bikes are so dangerous that only a suicide bomber would ride them.

Some folks would think that after Forty years of CF bikes .... people might accept reality ... but I guess there have always been people who don't realize that reality means "Not the stuff I make up in my own head."

Best part of the Internet is now they can reinforce each other.

We can all join the Illuminated Brotherhood of Asploding Carbon Fiber .... sponsored by the Flat Earth Society.

The best part is when people explain that they have been riding on various frame materials, with various brake systems, for several decades and don't have the same experiences ... people come back with, "It is easy to tell the people who don't ride."

So ... accepting reality and learning from experience instead of imagination equates to "not riding a bicycle"? Wow. Thanks so much. I just realized I Haven't been cycling safely on a variety of frame materials with a variety of brake systems for five decades.

One can learn so much here at BF.

Or not.

(P.S.: Great thanks to @jefnvk and @Lazyass for the airport jokes. Prime material, perfectly delivered. Naturally some people refused to accept delivery ... but the sane world was entertained. (So was I.)

bruce19

Isn't it true that the rim of a wheel is spinning at a higher rate of speed than the hub?

Leebo

How would it stay attached to the hub? Same rpms. Might want to join the flat earth posts.

DrIsotope

The hub and the wheel are moving at the same speed, but at different vectors. All parts of the wheel/tire cover the same distance in the same time. Where it gets in your head is the relativity: compared to the contact patch, the top point of the tire is traveling infinitely faster than the bottom, because for the millisecond that the tire is in contact with the ground, that part of the tire has a forward velocity of zero.

3alarmer 

...isn't it a simple time/distance function ? No need to invoke relativity here, sir.

DrIsotope

Relativity is involved whenever time is involved. No one is allowed to decide that relativity doesn't get to play the game.

Because at 30mph, the 12 o'clock position of the tire is moving @ 30mph. Meanwhile, the contact patch is moving @ 0mph. The top and bottom of the tire are moving at different speeds relative to one another. Relative to my desk, I'm not moving. Relative to the Sun, we're all doing about 67,000mph.

bruce19

I think that we can agree that one complete rotation of a wheel at the rim or hub are accomplished at the same time. But the circumference of the hub and rim are vastly different. So, why isn't speed different?

I found this on a science site...."The angular speed is the same regardless of distance from the point of rotation, since angular speed is defined as the following:

ω=dθdt

therefore, it is clear that since every point along the merrygoround covers the same angular distance (theta) then their angular speeds are equivalent.

However, the linear speed isn't. Looking at it from a standpoint of how much distance does it actually cover in a single rotation, you can tell that it covers more distance the farther out you go."

So, not being a science guy, I was wondering if stopping the the wheel at faster speed of the rim is more difficult than stopping the hub.

DMC707

I just bought a new disc brake road bike. The shop also routed the brakes moto style for me, (front brake on the right)

I will let the hospital staff know to update this thread next week when i endo it for the first time.

All kidding aside (wasnt kidding about the new bike though) -- i have had situations on mountain bikes on descents where the rim heated up so much from braking the ultralight latex tubes i was using popped.
A super technical descent for me at Angel Fire on my downhill bike, the brakes smelled like a burned clutch when i got to the bottom , and yes -- some brake dragging was involved
But nobody is really debating their relevance on MTB's