bleui

it's called minimizing the risks

WhyFi

By doing things like providing better and more consistent braking performance? Agreed.

Racing Dan

If one would want to minimise risk in bicycle racing there are many better ways to achieve that, than banning better brakes.

seau grateau

So if disc rotors can't cut like that, what sharper thing on the bike did?

CliffordK

So, apparently we have 3 bikes involved in the accident, presumably all with discs.

Katie Compton (who got cut on her right leg, I think).
Helen Wyman to her right and Nikki Brammeier to her left.

Now, let's see, typically one has left rear, right front for the rotors, right?

That means Katie likely either hit her own right front, or Helen's left rear. Anyway, one would think the race organizers would sequester all 3 bikes, and try to get to the bottom of the disc thing.

Bladed spokes? Bash guards, or lack of bash guards? 1x vs 2x vs 3x gearing? Exposed cables without full length cable housing or internal routing?

As others have mentioned, look for blood, flesh, DNA, etc. Of course, if they all rode in the mud for an hour after the incident, physical evidence may be a mess. Heck, Katie could have left a blood trail in the mud that others picked up.

Were they all using round edge brakes?

Is rotor design part of the bike safety check at the starts? This is a pro race after all (I think). Hopefully the riders/teams can either afford to buy good/safe equipment, or at least take the bikes down to a local shop and sand the rotor edges smooth.

I watched the Jeremy Powers video. It doesn't tell one a thing. First of all, he slows/stops the wheel in a few seconds, not instantaneously, and pressure is light, whatever he wishes to put on with his hand, not getting slammed into the thing with force. And thick skin (palms/soles) acts very differently on the body than the rest of the skin on the body.

Nonetheless, rounded edges are a step forward.

One could also likely make bi-metal laminated rotors of any thickness desired, so if 2mm isn't thick enough, make them 3mm or 5mm.

CliffordK

Looking at the cuts on her knee. There appear to be 2 cuts in a line. One at the patella, and one below the patella. Both cuts appear to be clean, with a scratch between the two.

Anybody drop a surgical scalpel on the course?

So, thinking of stuff that might cut a person on a bike:

• Rotors
• Chainrings (If 1x, may be protected by chain, also should leave a jagged cut)
• Bash Guards (did they use them? Potentially could do a rotor-like cut, but would also likely have chain and chainring bruises/tears.
• Pedals. (Not quite sure. My XPedo pedals look like they could be sharp, potentially even hopping cut if pedal rotates, but it would seem more like a tearing cut than a slicing cut).
• bladed spokes. (less likely to cut shins than elbows, fingers, knees).
• Unprotected cables (Possible??? Fingers? Hands?, also not really a gouging type of cut).
• Missing bar plugs (round plug cutting?)
• Anything broken or cracked (wild card??? If CF, would probably leave debris in the cut, and should be obvious, although blood doesn't necessarily occur immediately.
• ???

Anyway, for her cut, one quickly reduces it to a few more likely candidates including broken parts, skeletal pedals, and rotors.


Actually, if she snagged 3 things, Patella, Shin, and Shoes... That really is kind of odd. I don't think a dull rotor would do it, but a sharp rotor might.

WhyFi

NDS, front and rear.

FBinNY 

I'm not a fan of disc brakes on road or CX bikes, especially for competition, but my concern is less about safety than about other considerations.

In any case, I don't understand why disc advocates and users don't at least demand some effort at making them safer. It's technically not difficult (though it would add slightly to cost) to improve safety by turning a semicircular edge on the discs. They'll still be thin, but at least they won't be razor sharp.

So, to the true believers, DEMAND that some (minimal) effort is made to address this safety issue.

CliffordK

They likely would sharpen slightly through use, but at least start with round edges.

As far as I can tell, the greatest risk is with mass-start races, I.E. road racing, cyclocross racing, and perhaps cross country MTB racing. Much less danger for the casual commuter or solo events.

But, yes I would think the UCI and other racing organizations would mandate at least round (not sawtoothed) discs, with beveled edges. And the early adopters would also attempt to make their bikes as safe as possible for all. Especially in team events when one is just as likely to injure another teammate as someone else.

FBinNY 

There's no reason for anything to change with wear as long as the pucks are fully inboard of the edge as they are on both cars and motorcycles.

I expect that my suggestion (which nisn't uniquely mine) will be adopted soon enough, either by UCI mandate as a condition for allowing discs, or (more likely) by the major players because failing to do so without a sound technical reason leaves them vulnerable to injury lawsuits.

I, for one, would not want to be an engineer being deposed and asked "is there a reason that you didn't radius the edge to eliminate the razor edge which sliced up......?"

znomit

Give me a nice hot rotor over a filthy greasy chainring any day.

Where are all the chainring horror stories?

02Giant 

There is a misconception here. There doesn't need to be a sharp edge, to be cut by a rotor. An impact by an object can be quite effective.

CliffordK

Easy enough...

You point to the boss and say that it saved a nickel in manufacturing on $20 item, when one adjusted the cost for a million produced/sold.

For some reason there has been a movement to non-round outer edges on the rotors. Returning to round edge rotors will make adding the radius easier, as well as potentially making an impact have less risk of cutting.

Will we also see rotor shields?

FBinNY 

Agree 100% However, are you seriously suggesting that a sharp edged disc isn't more likely to cut, or to make a deeper cut than a rounded one?

Nothing is foolproof, and in the context of the normal risks of bicycling, the added risk of getting cut by a disc isn't all that high.

But minimizing it isn't difficult, and the cost/benefit ratio of the small added cost or dulling the edges, which in no way impairs performance, is hard to argue against.

FBinNY 

I don't think we have to go crazy. After all disc brakes aren't new, and have been around for years in mtb. If there were a high risk of getting cut, we'd have heard about it by now.

The issue relates to the nature of road and to an extent CX racing, where there's more crowding and multi bike crashes. It's that density that creates the added incidence of cuts.

I also suspect that disc size may also be a factor (only a suspicion of a possibility, so pretty nebulous). Discs have been getting larger, either to reduce fade or stress on the fork blades (or maybe just a fashion statement). Larger discs' rims are farther from the cone formed by the spokes, so there's some increased exposure there.

Either way, I'm only arguing for reasonable, inexpensive tweaks to mitigate the hazard to the extent that it's possible without affecting performance. It may only be a marginal improvement, but then again it's also a minimal hardship on manufacturers.

canklecat

Probably a split rather than cut. Looks similar but any blunt impact against bone can split the skin. Technically all "cuts" in boxing are splits (assuming nobody sneaked razors into their glove). The blunt impact of a gloved fist against bone -- usually the cheek, forehead, eyebrow or eye orbit -- causes the skin to compress and split open.

A good whack with a pipe (such as a bike frame) could do that under the right conditions. A disc brake rotor certainly could. It doesn't need to be sharp. Just the right impact, compressing skin and flesh against bone, and it'll split open.

I'd still be more worried about chain rings than disc rotors. I'd even be more worried about cranks and pedals. But disc rotors look like scary pizza cutters.

Should be easy enough to test the edges of the suspected bike to see which bits have the injured cyclist's blood and tissue.

02Giant 

Not in the slightest. Common sense would dictate that the part is rounded as you suggest. But, the edge of a disc can be rounded and still make a cut like that shown in the link. The cuts will not go away with disc rotors having round edges.

02Giant 

Agreed. I have a 4" scar on my calf from a work accident. A piece of 4" wide, 3/8" steel plate impacted my leg. When it happened, it hurt like ****. I was trying to walk off the pain when I looked down and my boot was red with blood. My jeans didn't have a cut on them.

qcpmsame 

I believe I found the problem here.

Bill

WhyFi

Disc advocates don't demand it because it's assumed that that precaution is so 'no duh' that it's already largely in place.

I think that the anti-disc crowd believes that discs are razor-sharp deli slicers because they've never touched one. I think that the pro-disc crowd believes that they're mostly harmless dull discs because they *have* touched some (or many). The OP says that some of the SRAM discs aren't/weren't rounded or chamfered - that's dumb, if true, and news to me; every Shimano and Avid disc that I've come in contact with is boringly dull.

WhyFi

As previously mentioned, every disc that I've come in contact with is already rounded/chamfered. Every manufacturer also has a min thickness spec, so it's pretty easy to ensure that the edge is suffeciently dull throughout its projected lifespan.

Racing Dan

What I dont understand is why those concerned about "disc safety" isnt also concerned about all the other safety issues relating to bicycle racing. Why arent you demanding, say, chain ring guards and body protection. Your focus seem oddly laser beam like and unbalanced. Lots of crashes and injuries happen i bicycle racing and im betting many injuries could be less severe if safety was taken into account outside of demanding riders wearing a helmet.

WhyFi

I think that a lot of the disc push-back in the pro road racing ranks is more about riders not wanting equipment choice dictated to them and they're using safety as a scapegoat.

I think that a lot of disc push-back in the amateur ranks is more about ever-changing standards and the notion that Evil Big Bike Corp is shoving change down their throats, so they're using safety as a scapegoat.

athrowawaynic

I've seen similar casued by soccer cleats, so basically... most of the nuts on a bike, QR/TA, brake/shift levers, the race course itself. (EDIT: Oh, and the cleats some riders attach to their shoes--I'm not talking about the pedal cleats--I'm talking about the soccer/football/rugby cleats that screw in at the toes.)

But what makes me doubt the disc is because you pretty much need to stick your limb through the spokes to contact the rotor.

FBinNY 

I don't speak for anyone else, nor do I let others speak for me.

If you'd read my post with an open mind,without categorizing me, you'd have noted that I made a very modest suggestion, specifically that reasonable effort is made to minimize (not eliminate) the risk of cuts from discs.

Doing so wouldn't impair function or cause any other issues, so there's no reason not to. This is different than objecting to disc brakes outright, or adding a major complication, such as a disc guard, which may cause other issues.

I do make similar demands on other components, namely eliminating or mitigating hazards where possible, and to the extent that it's possible, so your objection that it's only about discs isn't valid.