And if you think a micro second dab of a shoe on Kittels disc is applicable to a several second burst on the trainer, you can borrow my brush when I'm done :-)

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

You know shoes usually have feet in them, right?

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http://ironvision.blogspot.com ; @drSteve1663

Soft squishy feet? (relative to a steel disc rotor)

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

You may need to see a podiatrist. If you push on a shoe that has a foot in it there's relatively little give. The relative hardness is immaterial, the compressibility is the issue.

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http://ironvision.blogspot.com ; @drSteve1663

Show me the video...attach a flywheel to the spinning wheel that matches the kinetic energy of the situation, and then jam a Giro Empire shoe into the disc with a human foot "analog" inside and see what happens.

Let me turn this around then...do you really think such a clean slice to the shoe could be created by being dragged across a jagged, rusty foot of a barrier (which he clearly contacted first with his back)?

Do you not find it odd that the mark in the top of the foot is EXACTLY what one would expect from the edge of a disc rotor?

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http://bikeblather.blogspot.com/

If it happened the way I think it happened, that little ''dab" of a shoe stopped Kittel's bike dead and sent him over the handlebars.

Take two blocks of styrofoam. Gets your disc brake spinning up to speed. The first one, apply pressure like they did in the velonews video. The second one slam against the brake like an instantaneous collision. Report back what happens.

But to stop the wheel, the shoe would have had to go into the spokes. Surely it's more likely a spoke caused the cut, not the rotor. And did Kittle go OTB because he heaved on the front brake (he's on disc brakes and instinct after years of riding rim brakes might have kicked in) rather than Doull's shoe being the cause of the abrupt cessation of forward motion?

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Trust me I’m a doctor!
Well, I have a PhD :-)

It's entirely possible. I have stated before that I don't know what happened for sure. What I have seen, leads me to believe his foot jammed in to the rotor. I think Tridork is being entirely disingenuous with his arguments against that happening.

With the cut being on the inner half of his foot, and being mostly straight up his foot, I don't see how that would line up with the spokes cutting it. If it were a spoke, I would believe the cut would have been more across his foot than up and down it.

Kittel definitely could have grabbed a fistful of breaks, but a fistful of rim brake in that situation would still send you over. I would like to think an experienced and accomplished sprinter knows better than that.

No, it wouldn't need to go into the spokes. Besides, show us how a spoke could make that cut, including the mark on his foot that's the width of a disc rotor :-/


You don't have much experience riding disc braked bikes on the road, do you?

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http://bikeblather.blogspot.com/

Several years ago I was heading out my driveway from my bike shed, to ride to work. I came around my garage and turned left from the path, onto the driveway. Walking pace. Then I turn right to go down the drive to the street. Traditionally I would mount my bike at this point. I click into my left pedal with my left shoe, while turning slightly right. As I complete the right turn, pushing the pedal with my left foot, I complete mounting my bike and click in with my right shoe as I ride away down my driveway. All good.This particular morning I hadn't noticed the chain had come off the chain ring. This meant that as I pushed with my left foot, intending to ride away, my left foot went straight down from TDC to BDC, and the bike came to almost a complete stop. Rather than my right leg swinging over my bike, it too went straight down. My right shoe went into one of the bladed spokes, resulting in a near identical cut through my shoe, to what Doull got. My cut was slightly diagonal, but still pretty straight (remember the dish on the rear spokes). It completely cut through the front Velcro closure of my MTB shoe and put a cut most of the way through the second Velcro strap. the 3rd ratchet strap was undamaged. As I fell, my knee bent two other spokes and sustained a couple of cuts deeper than I'd like to have go, plus some grazing. Blood all over my bike and my driveway. My right hip ended up bending the rim.

Sure, it's an N=1 incident, but combined with the video evidence of the shoe against the spinning disc, that lead me to believe that it's more likely that a spoke is the culprit than the disc. Note that a shoe jammed in the spokes of a wheel will jam a wheel pretty well too.

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

See, that is at least a decent argument. It could be have been spokes, but I just don't think the cut aligns correctly for that to have happened.

While my spoke cut was slightly diagonal it was from say 11:30 to 5:30 on my shoe, not 12:00 to 6:00, it was pretty darned close to the same as Doulls cut. Because I fell strangely, that's how my cut happened. I was more worried about the blood pissing out of my knee!. In true HTFU style, I ran inside, put a bandage on my knee, swapped out the rear wheel with an old spare I had lying around, an headed to work. I still had time for my coffee at the ferry terminal before heading across the harbour.

At least Doull will get a new bike and new shoes without arguing with my %$&#ing insurance company!

Now I walk part way down my driveway, stop my bike, swing my leg over my bike and clip in with my right shoe first, then pedal away. I don't clip in my left shoe until I get out to the street (knowing that my chain is on). Most mornings I leave in the dark so looking at my chain isn't really much use. It's too hard to see at O'Dark Thirty.

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TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

Can someone tell me why everyone is so afraid of discs but not of cranks? They're both rotating discs of sorts, only one is way bigger and covered in sharp jagged teeth. I understand the disc rotates faster, but still. I guess I'm somewhat biased because I have a fairly large scar from a crash where a crank embedded itself into my thigh requiring quite a few stitches.

Saying that something else is more dangerous doesn't mean that the original thing is safe, but for a variety of reasons I still remain unconvinced on the apparent danger of disc brakes. Not the least of those reasons is that most of the arguments presented about why they are dangerous seem to be in the context of the pro peloton, i.e. very large groups of riders packed extremely close together traveling at very high speeds. That scenario applies to what, 0.1% of cyclists? Yet we should use it as proof that discs aren't safe for recreational riders? Or better yet, for triathlon where rules specifically prohibit congregation of riders?

Also keep in mind that 2/3rds of a chainring's "sharp jagged teeth" are covered by the chain.

So lets just put to rest this argument. In order for shoe to stop the rotation of the wheel it would have had to go into the spokes and jam against the fork.

On the 9100 shimano disc rotor there is no opening for a shoe to fit, wedge, and jam the rotor. Furthermore, as we know from many many sharp rotating incidents, any thing that jams into the open area of a disc rotor will receive heavy shear slicing. AFAIK there were no shear slices or missing toes from Doull's shoe. In fact I'd argue that his shoe can't both jam the rotor and be cut by the rotor edge.

9100 Shimano disc rotor. Please identify where you jam a shoe into this rotor to stop wheel rotation.

That's not always a good thing in terms of safety. Particularly on a fixie or track bike, where fingers have been taken clean off. Sometimes just by getting lazy while lubing the chain on a bike stand.

No one is suggesting there are not existing components that can cause injury. Chainrings can be nasty if you are unlucky. Unplugged bar ends can be nasty too.

But does different braking tech change the risk imposed by a chainring? That's a more relevant question in context of this discussion.

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http://www.cyclecoach.com
http://www.aerocoach.com.au

If the shoe need not go into the spokes to stop the wheel how else could it be stopped by the shoe and still be close enough to the rotor tout the shoe at the same time?

And what's experience with disc brakes got to do with it? You clutch a handful of front brake lever hard and, disc or rim, what's the chances of going OTB?

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Trust me I’m a doctor!
Well, I have a PhD :-)

Ummm...no. You're misunderstanding the orientation of the shoe to the disc.

Also, on those specific discs you show above...can you tell me what the additional "power to rotate" cost is of those cooling fan blades they incorporated into the mounts? Asking for a friend ;-)

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http://bikeblather.blogspot.com/

http://cycling.today/...y-to-his-hand-video/

And yes I know it's not the same as a body traveling at high speed into a disc brake

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Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

Because I can tell you from first hand experience that's not likely traveling at that speed on the road on level ground. Grab as much front brake as you'd like...you aren't going ass-over-teakettle.

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http://bikeblather.blogspot.com/

Let's see him try doing that while riding the bike at the same wheel speed ;-)

Want to take bets on the outcome?

Apples and oranges. "Bro science" :-/

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http://bikeblather.blogspot.com/

All of these tests showing up are quite flawed and I agree that people need to brush up on their physics. I wonder if you could put a rubber gasket around the edge of the disc?

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Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

I'm partial to gaskets shaped like a GP4000S.

That is my point. If the shoe is aligned such that the cause of the longitudinal cut is from the rotor edge then it can't also be aligned to jam into the rotor and stop wheel rotation. From inspection of the rotor we see that a foot can't jam into the rotor. Therefore if the shoe caused the wheel to stop it first has to contact the rotor edge to product the cut and then jam into the spokes/fork to stop the wheel. You state (and I agree 100%) that the kinetic energy is high for the bike system, dramatically higher than wheel alone spinning. This kinetic energy also means that any contact of the shoe and rotor edge would never be enough to slow the bike system any appreciable amount, much less stop wheel rotation and throw kittel forward.

I don't care about power to rotate, that is a topic for your thread debating the technical merits of disc brake performance. It has nothing to do with the the cut to the shoe and safety risk of disc rotors.