Disk brakes cause spoke breakage!

[mcteague]

Disk brakes cause spoke breakage!

Kelderman blames disc brakes after losing 10 minutes at Giro d'Italia

https://www.cyclingnews.com/news/kel...-giro-ditalia/

Tim

[yarg]

I'm calling BS on this, at first thought the physics say no, air is such a poor heat conductor and there is so much of it rushing by both the rotor and spokes at those speeds. Just my first impression though.

[Black Dog]

Yea...the temps needed to induce spoke failure would be very high. Not going to happen with discs over heating.

[rustychisel]

Originally Posted by yarg

I'm calling BS on this, at first thought the physics say no, air is such a poor heat conductor and there is so much of it rushing by both the rotor and spokes at those speeds. Just my first impression though.

agree. I've been waiting for this argument to surface, and frankly surprised it's taken so long, but I call BS also.

Physics, y'know.

[prototoast]

The heat explanation seems completely implausible, but I thought it was generally accepted that disc brakes cause extra stress on spokes, which is why disc brake Wheels generally have a slightly higher spoke account then they're rim brake equivalents.

[GregL]

His bike/wheel sponsor (Specialized/Roval...) has got to love that article, complete with a photo clearly showing their logos all over bike and wheels. Talk about biting the hand that feeds you...

Greg

[callmeishmael]

Originally Posted by prototoast

I thought it was generally accepted that disc brakes cause extra stress on spokes, which is why disc brake Wheels generally have a slightly higher spoke account then they're rim brake equivalents.

As did I, but I'm no engineer/physicist.

This is kind of a Mollema moment

[benb]

Somebody needs to have him touch his rotors after a long descent and then touch the spokes.

After he gets done cursing the burn from the rotors he'll notice the spokes are at room temperature.

Then he can go do it with rim brakes and burn himself on the rim and then notice the spokes aren't hot on that setup either.

He's 6'1" and claiming 143lbs so it's not a weight issue.

[Mark McM]

Originally Posted by prototoast

The heat explanation seems completely implausible, but I thought it was generally accepted that disc brakes cause extra stress on spokes, which is why disc brake Wheels generally have a slightly higher spoke account then they're rim brake equivalents.

Disc brakes cause extra stress on front wheel* spokes, which is partially from the braking torque, and partially due to the need to dish the front wheel. Spoke stresses due to braking torque are still less than weight bearing stresses, and even without the torque stresses, you'd probably still want to increase the spoke count to regain the lateral stiffness lost from the dishing.

As far as the heat explanation, tandems have used hub based drag brakes (usually drum brakes) for many decades, and these can get ridiculously hot, but they don't appear to result in an increase in spoke failures.


*On the rear wheel, spoke stresses from drive torque are greater than brake induced spoke stresses, so the number of spokes on rear wheels is often the same between equivalent rim and disc brake rear wheels.

[MikeD]

What kind of spokes in the wheel? If not steel, then the man has a case.

[Dude]

His teammate won on the exact same setup.

[batman1425]

Pro cyclists are worse than F1 drivers when it comes to the technical excuse-ery


Sent from my iPhone using Tapatalk

[bikinchris]

A wheel is far more likely to fail from poor building than from heat. IF the rotor heated the hub enough to affect the spokes, the grease would have caught on fire first.

Tandems have been using disc brakes for decades and if getting the rotor hot made the spoke fail, it would have happened there first. There was an article about a Santana tandem trip that rode Mt. Ventoux and one curious stoker touched the drag brake rotor at a stop and got badly burnt doing so.

[Spdntrxi]

so the radiant heat from a rotor caused the spoke to break... wow man ? Garbage

[tomato coupe]

$5 says the spoke broke at the nipple ...