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PostPosted: Sat Apr 06, 2013 8:23 pm 
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This is a fun thread, lots of good information!

I don't doubt that there were many who resisted disc brakes when they started putting them on cars! :)

And yes, I do understand that a car and lightweight bike are two entirely different worlds.

I bought a Trek CrossRip in January. To me, it is an inexpensive, relaxed geo road bike with discs.

I've never owned a high-end bike so I can't compare it with the best calipers, but even with BB5s the disc braking is magnificent! The modulation/control couldn't be better; the harder your squeeze the faster you stop, period, unlike calipers that hit a max braking level that doesn't increase with more pressure. They're not even slightly grabby, unlike some calipers I've used.
To me the best thing about discs is the consistency and control; the linear operation no matter what the conditions.

We've all had those moments when we soiled our drawers 'cause we were death-gripping the brake levers and just weren't stopping fast enough. That has never happened for me with these brakes (knock on wood!) I feel much more comfortable riding around town, in traffic, knowing that at slower speeds I can stop almost instantaneously.

My bike came with "sissy" levers and just one finger on those will initiate powerful braking. They're not WW but I love them because even when I'm on the tops I'm not far from the brakes if I need them.

I joked on another forum that I'll be blowing past everybody on the descents, 'cause I've got such amazing brakes!

I'm in the planning stages of building a tourer with discs. At this point you'd be crazy not to put them on a touring bike.

Final thought: The teenager that works at the LBS told me that the first time he went down a long descent on his mountain bike, the front rotor turned blue! Wow. :shock:


Last edited by Randy99CL on Sat Apr 06, 2013 9:03 pm, edited 1 time in total.

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PostPosted: Sat Apr 06, 2013 8:53 pm 
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maddog 2 wrote:

The aero thing is something that people get in a tizz about but disc rims can be made lighter and more aero, and made with carbon without the braking issues that some have, so overall I'd say this probably evens itself out.


We've already got wheels with negative drag at some yaw angles from the Firecrest/Stinger design; how much more aero do you think rims are going to get? Zipp and other companies are using rounded/canted brake tracks, so what other improvements at the tire/rim interface do you really foresee?

As Madcow pointed out, Cervelo has talked about HUNDREDs of grams of drag added through discs, but going from the old Zipp/Hed shape to the new blunt shapes was a bit less than that, around 40-50 grams, and it was a complete revolution of wheel design. I'm sure wheel companies will continue coming up with "revolutionary" designs that take off grams of drag but from the preliminary talk of what disc brakes ADD, I don't think there is a thing you could do to the rims that would offset that added drag.

Now of course, maybe we can integrate disc brakes and make them more aero, and use 120mm discs that are "aero" and in the end it'll catch up in the aero realm, but that seems to be down the road.


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Posted: Sat Apr 06, 2013 8:53 pm 


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PostPosted: Sat Apr 06, 2013 9:23 pm 
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Location: Natovi Landing
1415chris wrote:
@ bm0p700f Move just few miles south and you should be fine :wink:
And with the highest point of the county 128 m (420 ft) you still need discs....?

Personally, I wouldn't like to be forced to go for discs at all. I hope that the market and industry will leave this as an option only, not necessity.


You are too cruel.


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PostPosted: Sun Apr 07, 2013 3:06 am 
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prendrefeu wrote:
spytech wrote:
Carbon rims delaminate when braking hard and long with rim brakes- fact


They did. Years ago. They don't anymore. Even the "ooooo scary don't trust them" open mould wheels perform very well on steep, long descents. Where have you been?
.


Well I've been mostly in the Alps and Dolomites with occasional forays to Northern Europe, the UK and Thailand, and they are shite. I can say this because I ride in mountainous terrain daily. I might ask where have you been if I were to be impolite.

I should perhaps add that I would only want discs if I continued riding in the mountains. In the UK, wet weather braking is limited by the rubber in my experience.

But I see bike bike manufacturers like Cervelo trying to scare people simply because they have a stock of non disc framesets to sell. That should be born in mind when looking at their comments. Stick a disc on a standard bike and maybe it's a problem. Put it in a cowling and design aero rims without the contraint of braking surfaces and things may well be very different.


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PostPosted: Sun Apr 07, 2013 3:58 am 
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You want a cowling over your disc?


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PostPosted: Sun Apr 07, 2013 4:11 am 
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prendrefeu wrote:
Show us a lighter rim that is designed for disc specifically. Are there any changes necessary to strengthen the rim in order to balance against the braking force to the spokes & nipples now with discs? (Honest question)


i recall in the mid-late 90s when the transition to discs on mtbs was occuring that there were notable changes in rim design as a result of the removal of the brake tracks. it was sold to us at the time as "better" (stronger, lighter, faster) but i can't find anything to back up that assertion so i'm just as likely to think that it was as much about them being cheaper to manufacture.

personally, i won't run discs on a race bike unless it's getting raced down considerable hills at which point i see it as a distinct advantage (i'm a 90kg rider). pancake flat crits? you're probably not braking much (I race on a lot of square/rectanglar courses with wide, flat-out 90deg corners) but if you are your rim brakes are going to do fine.

for a training, commuting or sportive bike, whole other story...


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PostPosted: Sun Apr 07, 2013 4:20 am 
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Location: Los Angeles / Glendale, California
airwise wrote:
Well I've been mostly in the Alps and Dolomites with occasional forays to Northern Europe, the UK and Thailand, and they are shite. I can say this because I ride in mountainous terrain daily. I might ask where have you been if I were to be impolite.


I ride daily, 4 days a week (business day rides) in the Hollywood Hills / Bel Air area. My typical route is about 25mi with 4,000ft' ascent. The descents are typically steep, tight turns with blind corners. The max gradient on my daily routine, which I do often but alternate because I get bored with too much repetition, has a quarter mile at around 17%. That's on the 2nd climb of that route, and it follows an earlier (and much more precarious) descent of around 14-16% (with vehicular traffic on a single lane road). These are highly populated residential areas with drivers of very expensive vehicles and an invalid sense of entitlement - which means emergency braking when they decide to emerge from their driveways suddenly, or when they decide to switch into the on-coming lane of traffic around a corner that you are descending, and so on. It's surprising how quickly you want to stop when you realize that hitting a Zonda or 458 Italia will be much more expensive than the medical bills alone.

Sometimes, mid week, I'll sneak off for a longer ride in the Santa Monica Mountains.
Weekends are spent doing long days in the saddle, usually focused around climbing. Santa Monica Mountains (sometimes steep, but typically technical descents with off-camber turns and inconsistent radii) are the easiest playground because I ride from my door to them, just like the Hollywood Hills / Bel Air area. I also do plenty of riding in the San Gabriel Mountains and the higher and lower Sierras (it's well worth the travel time). Plenty of climbing, plenty of descending at high speeds, at high elevations, rough roads, smooth roads, wet roads, snowy days, hot days. Carbon clinchers, no issues to speak of.

Hope that helped, even if you didn't ask. Los Angeles is a massive metropolis that, by county, covers more than 88 cities and unincorporated areas. For some people who live in the 'basins' or at certain parts of the coast the riding can be flat. For many, however, there are considerable climbing hills in nearly every direction. It isn't surprising that many pro teams choose to spend their time holding training camps in this area. It provides a nice alternate to Mallorca if the budget allows.

These are not the European Alps, clearly. The Sierras might compare though.

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PostPosted: Sun Apr 07, 2013 5:15 am 
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airwise wrote:
Put it in a cowling and design aero rims without the contraint of braking surfaces and things may well be very different.


Can you explain why rims without a brake track can be more aero?

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PostPosted: Sun Apr 07, 2013 12:42 pm 
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Everyone is just waiting for UCI approval for their use in races by the Pro's.

Once that gets through the gate, rest assured, all the bikes and requisite matching parts will magically be launched within 1~3 months.


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PostPosted: Sun Apr 07, 2013 3:23 pm 
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Location: Santa Cruz, California, USA
prendrefeu wrote:
airwise wrote:
The Sierras might compare though.


The Sierra descents are not as steep or as technical as the So Cal (or NorCal) coastal mountains. Longer though!

I've ridden the SoCal and NorCal coast mountains a lot, and good rim brakes are just about always good enough for me. I have stopped once to let my rims cool, after a very steep but slow descent (slow due to poor road conditions- it's an abandoned road) on a very hot day.

More braking power isn't useful as tire traction limits braking.

I'm relatively light and know how to descend. Someone who is fearful of descents (a woman died on one of our steeper NorCal descents about eight years ago) who drags their brakes could possibly benefit from dics.... assuming they don't overheat and fade.

It will be interesting to see what comes out, but I am not expecting that a disc brake road racing bike will be in my future any time soon.


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PostPosted: Sun Apr 07, 2013 5:27 pm 
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Airwise, as I pointed out. Wheels are already very aerodynamic, some of them having 0 or less drag at 10-12 degrees. We've already got angled, slightly curved brake tracks on some wheels, what more do you think they can do in that area? And do you really think its going to make wheels markedly faster? Hed and Zipp after designing wheels with their traditional toroidal shape for 12-18 years just took a pretty big jump, I'm not so sure I'd hold my breath for another big jump, especially as a result of discs.

Also, do you really think cervelo is worried about their stock of bikes? They are definitely in the top 3 of engineering driven bike companies. They've been pushing aero for longer than anyone and, they make bikes people think are ugly because they believe the bikes are faster. Not only that, but independent wind tunnel tests back them up. I agree they want to sell bikes, but they've always wanted to sell the best bike it seems to me. If they wanted to just sell bikes, they could have made the S5 a lot more attractive.


Last edited by NGMN on Sun Apr 07, 2013 8:24 pm, edited 1 time in total.

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PostPosted: Sun Apr 07, 2013 8:17 pm 
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Location: Lancaster, UK
Quote:
Colnago sales haven't been all that good and that's a huge test


Yeah but that's one bike, lecky only and costs a fortune! Good example.

People talk about there being "no demand" for it but where do they get this information from? Out of thin air I suspect.The bikes aren't currently there to buy so how can you assess demand? You have silly expensive ones (Parlee, Colnago), some less than handsome ones (Volagi, Spesh), some unproven/untested Chinese frames (Hongfu) and a load of carbon CX bikes that aren't quite there as a roadie.

I have £2k sitting in an account ready to drop on a decent carbon disc frame. But I haven't popped up on the 'demand' radar because the right frame isn't there yet, so I haven't spent it yet. As I said, once the bike companies get something to market THEN we can talk about what the demand might be.


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PostPosted: Sun Apr 07, 2013 9:51 pm 
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maddog 2 wrote:
Quote:
Colnago sales haven't been all that good and that's a huge test


Yeah but that's one bike, lecky only and costs a fortune! Good example.

People talk about there being "no demand" for it but where do they get this information from? Out of thin air I suspect.The bikes aren't currently there to buy so how can you assess demand? You have silly expensive ones (Parlee, Colnago), some less than handsome ones (Volagi, Spesh), some unproven/untested Chinese frames (Hongfu) and a load of carbon CX bikes that aren't quite there as a roadie.

I have £2k sitting in an account ready to drop on a decent carbon disc frame. But I haven't popped up on the 'demand' radar because the right frame isn't there yet, so I haven't spent it yet. As I said, once the bike companies get something to market THEN we can talk about what the demand might be.



some good points well made. I think people with experience of disc brakes do want them on their road bikes....


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PostPosted: Sun Apr 07, 2013 11:13 pm 
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Location: Cambridge, New Zealand
NGMN wrote:
Also, do you really think cervelo is worried about their stock of bikes?


Cervelo still sell the P2 as fast as they can make it. People are still waiting for P5s. I'm with you - I don't think Cervelo is too worried about obsolete stock. Bit of a pity that they don't chase trends as an RDisc would be a rather nice addition to the genre for those that do want discs.

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PostPosted: Mon Apr 08, 2013 12:10 am 
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some general thoughts.

Disk brake bikes aren't likely to be marketed in the aero bike category so how aero they can be made is a bit of a non issue. Flanders, PR and LBL are all about this time and in rainy conditions brakes largely unaffected by rain and wheels that wont rub ith they get a bit out of true would be an advantage and aero hasn't shown much of a benefit in those races.

In at least one test of the Colnago the testing, a very experienced rider, remarked how the more confident braking enabled him to faster down tight turns as he could confidently brake later/harder.

Finally who knows what the aero benefit penalty would end up to be on parts not yet designed? If it was absolutely neccesary to have an aero disc brake then incorporating the braking surfaces oin the hub flanges, just below the spoke heads, with the pads comng out of the fork blades/chainstays, would make for a braking system that was essentially invisible. Still it seems like a lot of bother when the current crop of aero brakes are pretty good in most repects.


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Posted: Mon Apr 08, 2013 12:10 am 


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