Questions about bike hire abroad and everything light bike related. No off-topic chat please
Moderators: robbosmans, Moderator Team
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mergeforthekill
- Posts: 45
- Joined: Fri Jun 17, 2016 1:24 am
by mergeforthekill on Fri Feb 24, 2017 8:16 pm
Norregard wrote:kingkongsfinger wrote:mergeforthekill wrote:UpFromOne wrote:Mandate thin carbon fiber rotor covers to save weight. That way the spinning rotor can still do damage.
Motocross bikes have these. Not sure why they haven't tried this yet. They also make them for bikes.
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A "lot" of aero drag on the covers.
Standardise the use of the covers so everyone has the same 'disadvantage', problem solved.
Right, or im sure a manufacturer could make an aero cover that would likely make the whole of the brake more aero.
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Nefarious86
- Moderator
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by Nefarious86 on Fri Feb 24, 2017 8:45 pm
5 revolutions per second.. not exactly a heap of cutting force on a rounded rotor. I have the same rotors with plenty of km on them, still a dull edge, I'm going with the snagged barrier. Love can the comments that the smudge is a burn mark too.
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Miller
- Posts: 2764
- Joined: Thu Sep 21, 2006 8:54 pm
- Location: Reading, UK
by Miller on Fri Feb 24, 2017 8:48 pm
Rondje wrote:Almost every cycling related news/review/whatever website is sponsored by brands. And thus they are the advocates of the pro discs since they get payed to do so. I trust that VN clip just as much as I trust Doull.
Teams are sponsored by brands too. Brands put money into cycle racing as a form advertising, with the same reason as advertising, to increase profile and sales.
Have to say that I'm sceptical that a disc rotor cut Douill's foot. He's just gone piling into a barrier on his left side, and his left shoe is cut, so I would suspect something to do with a barrier.
I get that the riders don't see the need for discs, for a variety of valid reasons, but their cycling environment (homogenous groups of fit skilled riders, endless technical support) is not at all the same as that of an amateur.
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Sacke
- Posts: 643
- Joined: Fri Sep 26, 2008 2:33 pm
- Location: South of France
by Sacke on Fri Feb 24, 2017 10:11 pm
Regarding Sagans beard.
Last year it was unshaved legs, this year it's a beard.
I would put a careful bet that the beard comes off before the Ronde.
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KWalker
- Posts: 5722
- Joined: Mon Dec 28, 2009 8:30 pm
- Location: Bay Area
by KWalker on Fri Feb 24, 2017 10:39 pm
How about every major WT team or brand puts some portion of their budget into a test fund. Some independent testing agency then simulates race crashes with discs the same way cars are safety tested. Their conclusion about injury rate then determines disc usage. We would get a lot more out of this than we get out of the bottom 3 WT teams and certainly more than we get out of riders like Tyler Farrar.
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maquisard
- Posts: 3772
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- Location: France
by maquisard on Fri Feb 24, 2017 10:42 pm
KWalker wrote:Others have failed to mention how these factors actually would increase the force between the two contact points. I would like to hear how they would actually increase the cutting force compared to literally putting the shoe there and holding it for much longer than it would contact the disc in a crash. Crashes also stop the bike in most cases. So no, I don't think it's the same. Not until someone can actually demonstrate visually or with some kind of measurement.
F = ma
In the Velonews reconstruction, m is reduced as the mass of the rider attached to the bike and rotor are not modelled, neither is the mass of the rider attached to the shoe. Similarly a or deceleration is reduced as only the rotation velocity is taken into account, not the linear acceleration as the two bodies collided.
Crashes stop bikes in a crash yes, that is the point, where do you think the energy goes to when the bodies stop. The energy that isn't modelled in the Velonews reconstruction.
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KWalker
- Posts: 5722
- Joined: Mon Dec 28, 2009 8:30 pm
- Location: Bay Area
by KWalker on Fri Feb 24, 2017 11:41 pm
maquisard wrote:KWalker wrote:Others have failed to mention how these factors actually would increase the force between the two contact points. I would like to hear how they would actually increase the cutting force compared to literally putting the shoe there and holding it for much longer than it would contact the disc in a crash. Crashes also stop the bike in most cases. So no, I don't think it's the same. Not until someone can actually demonstrate visually or with some kind of measurement.
F = ma
In the Velonews reconstruction, m is reduced as the mass of the rider attached to the bike and rotor are not modelled, neither is the mass of the rider attached to the shoe. Similarly a or deceleration is reduced as only the rotation velocity is taken into account, not the linear acceleration as the two bodies collided.
Crashes stop bikes in a crash yes, that is the point, where do you think the energy goes to when the bodies stop. The energy that isn't modelled in the Velonews reconstruction.
Thanks for explaining basic physics to not make a point. Can you propose using your wide knowledge of physics how we can replicate a crash and how VN is wrong? Clearly contact time as well as energy is at play as well. If in the crash the rider's wheel stops and they grab the brakes, are you concluding that most or all of the energy is transferred into the rotor and item that impacts it? Because as a sheer object if it is stopped it is rather blunt and we can see that at race speeds it takes considerable time to slice, so there would have to be enough acceleration from a body or object colliding into it to make up for the lack of collision time.
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Mr.Gib
- Posts: 5577
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- Location: eh?
by Mr.Gib on Sat Feb 25, 2017 2:47 am
KWalker wrote:maquisard wrote:KWalker wrote:Others have failed to mention how these factors actually would increase the force between the two contact points. I would like to hear how they would actually increase the cutting force compared to literally putting the shoe there and holding it for much longer than it would contact the disc in a crash. Crashes also stop the bike in most cases. So no, I don't think it's the same. Not until someone can actually demonstrate visually or with some kind of measurement.
F = ma
In the Velonews reconstruction, m is reduced as the mass of the rider attached to the bike and rotor are not modelled, neither is the mass of the rider attached to the shoe. Similarly a or deceleration is reduced as only the rotation velocity is taken into account, not the linear acceleration as the two bodies collided.
Crashes stop bikes in a crash yes, that is the point, where do you think the energy goes to when the bodies stop. The energy that isn't modelled in the Velonews reconstruction.
Thanks for explaining basic physics to not make a point. Can you propose using your wide knowledge of physics how we can replicate a crash and how VN is wrong? Clearly contact time as well as energy is at play as well. If in the crash the rider's wheel stops and they grab the brakes, are you concluding that most or all of the energy is transferred into the rotor and item that impacts it? Because as a sheer object if it is stopped it is rather blunt and we can see that at race speeds it takes considerable time to slice, so there would have to be enough acceleration from a body or object colliding into it to make up for the lack of collision time.
For starters, how about putting a foot in the shoe? Sheesh, you shouldn't need to have a research background to come up with that.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.
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KWalker
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- Location: Bay Area
by KWalker on Sat Feb 25, 2017 5:07 am
A dummy foot could help, but I would wager the force of Caley pressing the shoe into the rotor is greater than that of a flailing leg.
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ALAN Carbon+
- Posts: 294
- Joined: Mon Dec 26, 2005 9:21 am
- Location: Canberra, Australia
by ALAN Carbon+ on Sat Feb 25, 2017 6:01 am
Given there is no foot inside the shoe for the velonews test, wouldn't the shoe be likely to partly deform when pressure is applied against the disc rather than retain its shape, potentially reducing the damage caused by the rotor.
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bikewithnoname
- Posts: 1734
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- Location: Paris
by bikewithnoname on Sat Feb 25, 2017 9:03 am
My favourite weekend of the year so far! Het Nieuwsblad and KBK (plus 6 Nations Rugby), the real racing starts today!
"We live in an age when unnecessary things are our only necessities." Oscar Wilde