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Old 07-06-17, 07:24 AM
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Originally Posted by work4bike
I've never used disc brakes before, but I've heard that they can really help with braking in wet conditions, so I'm considering getting them on my next bike, which I'm currently in the market for.

I don't know what the big controversy is around disc brakes in the tour, but I did hear one guy say it's all about braking times in the peloton, i.e. guys with discs can brake faster than guys with traditional brakes, which can cause accidents. Sounds a little iffy to me.
I read the write-up on disc brakes on Sheldon Brown's site, but my impression is that the write-up was a little dated. The overwhelming advantage to disc brakes to me seems to be their superior braking power in wet conditions -- I've had some scary times with wet brakes before.

I'm not a gram-wennie, so weight is not a factor, but I'm not seeing much here to address my questions. I guess I'll check out youtube to get the real deal on them.
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Old 07-06-17, 08:03 AM
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Imagine that you are a trucker running along in a big convoy of about 20 trucks. 53 footers loaded to the hilt. Most of the trucks have the standard air brake setup of the day including your rig. But 2 or 3 of them have that new fangled electronic/hydraulic/air/computer controlled braking sytem with auto correct. It reacts and stops about 30% faster than the normal setup. Are you going to want the trucks with the new technology rolling in front, or behind you? Same for the disc vs rim brakes. Every rider in the race has to have the same kind with the same stopping ability. It doesn't matter which as long as they are the same. The safety issue comes up when they are not the same and provide different braking characteristics.
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Old 07-06-17, 08:09 AM
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Originally Posted by seypat
Imagine that you are a trucker running along in a big convoy of about 20 trucks. 53 footers loaded to the hilt. Most of the trucks have the standard air brake setup of the day including your rig. But 2 or 3 of them have that new fangled electronic/hydraulic/air/computer controlled braking sytem with auto correct. It reacts and stops about 30% faster than the normal setup. Are you going to want the trucks with the new technology rolling in front, or behind you? ...
Applying an earlier comment -- the braking system won't matter if the trucks are running along 4 inches off the bumper of the rig in front.
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Old 07-06-17, 08:16 AM
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Originally Posted by Athens80
Applying an earlier comment -- the braking system won't matter if the trucks are running along 4 inches off the bumper of the rig in front.
You didn't answer my question. Which is it, in front, behind, or it doesn't matter.
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Old 07-06-17, 08:28 AM
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Originally Posted by seypat
You didn't answer my question. Which is it, in front, behind, or it doesn't matter.
It won't matter if neither system stops the bike and rider before colliding with the bike and rider four inches in front.
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Old 07-06-17, 08:39 AM
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Originally Posted by Athens80
It won't matter if neither system stops the bike and rider before colliding with the bike and rider four inches in front.
With the same system, each rider knows what the limits are of that system. But with different systems, different limitations.

With the example you keep citing, the disc brake rider now thinks he can get by with 2 or 3 inches instead of 4. Maybe he can. But the rider behind him on the rim brakes still needs at least 4. So every time that disc rider hits the brakes, he has another rider in his jersey with him.
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Old 07-06-17, 08:45 AM
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Originally Posted by seypat
With the same system, each rider knows what the limits are of that system. But with different systems, different limitations.

With the example you keep citing, the disc brake rider now thinks he can get by with 2 or 3 inches instead of 4. Maybe he can. But the rider behind him on the rim brakes still needs at least 4. So every time that disc rider hits the brakes, he has another rider in his jersey with him.
I don't get the deal.


You ride lazily by wheelsucking in bad weather (and dangerously)...you get what you deserve.

Riders piling up on one another due to tail gating are not the fault of the brakes...they're the fault of wheelsuckers not wanting to work and have a group training ride. It isn't like all rim brakes are identical anyway, between pads and rims and calipers and groupsets-every team bike handles braking differently anyway.
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Old 07-06-17, 08:58 AM
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In the pro peloton, I see riders avoiding the pile ups in front of them by riding around them, or on rare occasions, over them (Sagan in some Classic). If the pro just in front goes down, or slams on the brakes, the rider immediately behind is either going around, or is going down. The brakes on the bike in back won't make a difference.

Clearly, there is a separation amount where very different braking performance could be significant. I don't see that the pro peloton is often riding that way. They are too close together to rely on braking to avoid accidents. The ones that don't get caught up are those who maneuver around.
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Old 07-06-17, 09:08 AM
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Originally Posted by work4bike
I read the write-up on disc brakes on Sheldon Brown's site, but my impression is that the write-up was a little dated. The overwhelming advantage to disc brakes to me seems to be their superior braking power in wet conditions -- I've had some scary times with wet brakes before.

I'm not a gram-wennie, so weight is not a factor, but I'm not seeing much here to address my questions. I guess I'll check out youtube to get the real deal on them.
There's a good CGN video comparing the two. Bottom line is both are similar in dry conditions and discs are better in wet.

Discs are also better for long, steep descents.

Lots of reasons cited by pros for not using including problems with wheel changes, potential injuries in pileups, added complications, and many consider discs just aren't necessary because rims work fine in race conditions.
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Old 07-06-17, 09:51 AM
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I apologize, I actually had to do some work. Strange concept, actually working, at work. I had a good, long response typed out. Hit the refresh button and lost it all. Dang!

Gotta work some more.
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Old 07-06-17, 12:07 PM
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Yeap. I've learned to always "copy" after typing a butt-load, before doing anything else.
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Old 07-06-17, 07:59 PM
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Originally Posted by Dave Mayer
Likely Marcel Kittel on stage 2. Flat sprinter stage, so perfect for discs. The discs will be packed away as soon as soon as the climbing starts.
this would be true without UCI weight limits.

But with a mandated minimum 14.9lbs weight, you can build a disc brake at the limit.

So there's no weight penalty for a UCI legal disc brake bike.
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Old 07-06-17, 08:07 PM
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If I was racing in a race governed by UCI Rules,on a bike a sponsor paid for, I would absolutely be on discs, except for a TT.

There's a small advantage in wet weather, and no penalty because, the disc brake bike will still hit UCI minimum weight, particularly with my sponsor paying for the rest of the bike to be sufficiently light to hit the minimum weight limit.

Given that 98% of the races I do are not governed by UCI rules, i'll race my 13 pound bike with caliper brakes.
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Old 07-07-17, 03:29 AM
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Originally Posted by seypat
You didn't answer my question. Which is it, in front, behind, or it doesn't matter.

Differences in brake performance only matter if that difference is being used.


Let's say vehicle A has 20% (however that'd be measured) better brakes than vehicle B.


So when vehicle A breaks with 50% of available capacity, vehicle B has to brake with 70%.


Nothing happens b/c of the differences in brake performance no matter who's behind or in front until vehicle B is maxed out and vehicle A still has capacity to brake harder.


The reason why mixed traffic works, despite huge differences in vehicle performance is that most of the time is spent in the zone of overlapping performance.


Better brakes on a vehicle behind you is unlikely to cause an accident involving you.
But I suppose you could get rammed by a rider planning to brake harder and later.
Which is already possible, so that scenario doesn't add anything.


Better brakes on a vehicle ahead of you is unlikely to cause an accident involving unless that vehicle is braking hard enough to use that advantage.


Better brakes on a vehicle ahead of you can cause an accident involving you if that vehicle is braking hard enough to use that advantage.
But only if you "cooperate" by staying too close behind for the speed and performance of your vehicle.


Poorer brakes on a vehicle behind you is unlikely to cause an accident involving you unless you are braking hard enough to use that advantage.


Poorer brakes on a vehicle behind you can cause an accident involving you if you are braking hard enough to use that advantage.
But only if the vehicle behind "cooperates" by staying too close behind for the speed and performance of that vehicle.


And again, another condition that needs to be fulfilled for differences in brake performance to mean anything is reaction time. There has to be enough of it
In a tight peloton, at race speed, for most of the guys reaction time is the limiting factor.
They can't see far enough ahead to know when the guys ahead might be about to brake.
Brake performance doesn't matter if you've piled up before you've even started braking.


Keep in mind that a pro peloton might have a 25-30 mph average, with 2-3' rider spacing.
That is by definition not a legal, functional, normal traffic behaviour.
Accidents will happen, even if you'd have brake performance bordering on magic.
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Old 07-07-17, 10:50 AM
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based on limited experience trying bikes w/ CF rims and rim brakes I have to think I would prefer discs to CF rims/brakes especially in the rain, even if I were in the peloton and sworn to never brake ever.
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Old 07-07-17, 12:51 PM
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Originally Posted by merlinextraligh
this would be true without UCI weight limits.

But with a mandated minimum 14.9lbs weight, you can build a disc brake at the limit.

So there's no weight penalty for a UCI legal disc brake bike.
Not how it works. Regardless of the weight limit, you always attempt to shed rotating mass, even if you have to add weight to the rest of the bike. You can add useful weight by making the frame more 'aero'.

Besides, my bikes are not limited to UCI weight limits, nor do I suspect are the bikes of any of the posters here. Why would I want to add an anchor to my bling carbon bike with a pound of unnecessary weight? That is like converting a $8k road bike to a $4k road bike.

Second downside of road discs: the stigma when you show up on a group ride; it screams: 'newb'. Lessee, two such riders showed up on our last group ride. One got ejected off the front of his bike at the first hard stop. The second disappeared on the first climb.
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Old 07-07-17, 01:35 PM
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Originally Posted by Marcus_Ti
I don't get the deal.


You ride lazily by wheelsucking in bad weather (and dangerously)...you get what you deserve.

Riders piling up on one another due to tail gating.... wheelsuckers....
Well, racing, or at least riding in a race-like manner, isn't about being safe. Speed and efficiency are the priorities.
"Tail gating" and "wheel sucking" comes with the territory.

Which is why part of the resistance against disc brakes makes a bit of sense. For racing or riding in a race like manner, discs don't offer much advantage. At least not in the dry.



Originally Posted by Marcus_Ti

Riders piling up on one another due to tail gating are not the fault of the brakes....
+1
Originally Posted by Marcus_Ti
....It isn't like all rim brakes are identical anyway, between pads and rims and calipers and groupsets-every team bike handles braking differently anyway.
+1
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Old 07-07-17, 04:35 PM
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Originally Posted by Dave Mayer
Besides, my bikes are not limited to UCI weight limits, nor do I suspect are the bikes of any of the posters here. Why would I want to add an anchor to my bling carbon bike with a pound of unnecessary weight? That is like converting a $8k road bike to a $4k road bike.

Second downside of road discs: the stigma when you show up on a group ride; it screams: 'newb'. Lessee, two such riders showed up on our last group ride. One got ejected off the front of his bike at the first hard stop. The second disappeared on the first climb.
YMMV.

But the thread is about disc brakes in the TdF, in the Professional Cycling For the Fans forum. It's not about my bike or your bike or newbs on group rides. Kittel on a disc brake bike does not scream 'newb.'
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Old 07-07-17, 04:45 PM
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Originally Posted by dabac
Well, racing, or at least riding in a race-like manner, isn't about being safe. Speed and efficiency are the priorities.
"Tail gating" and "wheel sucking" comes with the territory.

Which is why part of the resistance against disc brakes makes a bit of sense. For racing or riding in a race like manner, discs don't offer much advantage. At least not in the dry.




+1


+1
A bit of sense...yet the racers are the employees of their sponsors including, but not limited to, transmission and therefore brake manufacturers. The UCI races are basically a tech showcase, where the newest toys are put out for popular viewing and drooling.


Imagine a "Ford" sponsored NASCAR racer telling the public not to drive 2017 Fords. Racers publicly expressing no-confidence in their sponsor's goods is rather a jaw dropping thing. I think it is not a stretch to say that most of us, if in front of national and international media, flapped our gums about our employer's latest-and-greatest being inferior or less-safe....we'd get our final paycheck the next day.

The resistance is funny and absurd. And odds are is only permissible because these guys are employed under EU employment law and not USA employment law.
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Old 07-07-17, 05:39 PM
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Originally Posted by Dave Mayer
Not how it works. Regardless of the weight limit, you always attempt to shed rotating mass, even if you have to add weight to the rest of the bike. You can add useful weight by making the frame more 'aero'.

Besides, my bikes are not limited to UCI weight limits, nor do I suspect are the bikes of any of the posters here. Why would I want to add an anchor to my bling carbon bike with a pound of unnecessary weight? That is like converting a $8k road bike to a $4k road bike.

Second downside of road discs: the stigma when you show up on a group ride; it screams: 'newb'. Lessee, two such riders showed up on our last group ride. One got ejected off the front of his bike at the first hard stop. The second disappeared on the first climb.
your comment related to Kittel getting rid of discs in the hills. He is subject to UCI rules.

and if rotating weight had such a big effect, he wouldn't be using discs on sprint stages where he has to accelerate that rotating weight.

I totally get not wanting to add weight to a low weight CF bike.

What your missing is my point that one of the reasons pros do it is that there is no weight penalty for them due to an artificially high UCI minimum weight llinit.
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Old 07-07-17, 06:41 PM
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Remember Huffy pedaling disc brakes back in the 70's? In wet conditions they work exceptionally well when compared to rim brakes. I had them on my mountain bikes and would not have traded them for the best rim brake in the world! On a road bike, unless you ride in wet weather, why bother with the hassle of maintaining them? Cable operated ones are not bad at all, however hydraulic is another level of complexity that I don't want in my life.
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Old 07-07-17, 06:50 PM
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Originally Posted by Dave Mayer
Not how it works. Regardless of the weight limit, you always attempt to shed rotating mass, even if you have to add weight to the rest of the bike.
The significance of rotating mass is to do with the radius about which it rotates, so there is basically no meaningful rotating mass on disc rotors pegged w/in 60mm of the axle.
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Old 07-08-17, 05:47 AM
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Kittel not using disc brakes today... and it's the first mountain stage. Makes you wonder what real world (as applied to racing which is different to the real world we enjoy) advantages they offer. It would appear downhills aren't among them.
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Old 07-08-17, 05:51 AM
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Originally Posted by europa
Kittel not using disc brakes today... and it's the first mountain stage. Makes you wonder what real world (as applied to racing which is different to the real world we enjoy) advantages they offer. It would appear downhills aren't among them.
Kittel is using a green-painted bike.

Looking at the racing, he and the sprinters may get eliminated if they aren't careful.
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Old 07-08-17, 06:21 AM
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Originally Posted by TiHabanero
... hydraulic is another level of complexity that I don't want in my life.
Decent hydros are probably the closest to fit & forget I've encountered as bike parts.
Like fuel injection vs carburetors, it's complexity the user today very rarely needs to deal with.
Ignoring my Tektros, my hydraulic discs have required less attention than my rim brakes.
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