Campagnolo Bora AC3 Braking Treatment

Everything about building wheels, glueing tubs, etc.
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Calnago
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by Calnago

@RyanH... Good pics and post. Your pics show clearly why the single pivot brakes do NOT have more clearance than the skeleton dual pivot brakes, despite what a few people might say. I learned this long ago while trying to install fenders on winter bikes. It is the arms that come down along the sides that create the clearance problem, not the small peak in the very center of the arch. Also, I mounted the Vlanderens on some Nemesis rims and put them in my C60. As expected, just like with the old Boras, the clearance is not sufficient to run that combination in my C60, whereas it is with the Boras. This is simply due to the rim bed having a more relaxed radius to accommodate the larger radius tubulars. Putting a larger radius tubular onto a smaller radius rim bed will always create a "push up" bra effect. While appealing in some scenarios, tire clearance is not one of them. I have a feeling my thoughts on the 27mm Vlanderen will be the same as yours... ok for dirt and really rough roads etc, but for most road scenarios, 24-25mm is really ideal, and if you're really light then I don't think there's anything detrimental about running 23's either.

Just to add the comparative pics of clearance between a 27mm Vlanderen tubular mounted on a new Bora rim versus the same tire mounted on a Nemesis rim....

Vlanderen/Bora rim (new)
Image


Vlanderen/Nemesis rim... simply not enough clearance...
Image
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Asteroid
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by Asteroid

Calnago wrote:
Vlanderen/Nemesis rim... simply not enough clearance...
Image


One sees this type of tight clearance, while riding behind another on their group ride.
It makes me a little nervous, because something that could distort the tire could lead to negative consequences.
Especially if the front looks similar.
On the other hand, it makes for quick debris removal. :thumbup:

This is a timely thread for me, since I expect delivery of some Bora Ultra 35 tubulars in a few days.
Which of my Veloflex models to use comes into play. Installing on a "dry run" makes perfect sense.
I also plan to look closely at the seams and brake track. Those are some nice pics you and the OP posted. Thank you for that.
Oldbie

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Calnago
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by Calnago

Ooops, forgot to answer a couple of earlier questions...

Imaking20: The wheels are coming into the country now so you should see more availability soon. The distributor I got them through is called Provision Cycling, in the US. Great guys to deal with.

@Nestornk: Haven't heard anything from Campy yet, will keep you posted.

Cal
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
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Imaking20
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by Imaking20

Thanks, Cal! :beerchug:
Current:
T2

Retired:
Blue | Project C6.0 | Felt AR FRD | Colnago C59 NERO | 2014 S-Works Tarmac | S-Works Venge | Wilier Cento Uno SL | Tarmac SL2

jonjones13
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by jonjones13

Calnago - yours appear to be the old version without the grooved brake track - the new ones look like this http://www.bicycling.com/bikes-gear/Cam ... AC3-wheels

RyanH
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by RyanH

If you look at Calnago's pictures closely, you can see the lines/grooves. It looks like Cal had to shoot the shot at an angle to highlight the grooves, so the stock image is probably digitally enhanced.
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Calnago
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by Calnago

jonjones13 wrote:Calnago - yours appear to be the old version without the grooved brake track - the new ones look like this http://www.bicycling.com/bikes-gear/Cam ... AC3-wheels

The "grooves" are definitely there, but they are very fine and I was trying to highlight the area at the layup intersect that I was a bit concerned about. People seem to be under the impression that those "grooves" are the big deal. They are not. Those grooves, despite what is said in that article you reference, are I believe really just a byproduct of the manufacturing process... they really don't "channel water" anywhere. But maybe Campy didn't bother correcting anyone and thought "Well, it makes for a good story, let's just let 'em run with it". In fact, if you look super close up at an older set of Boras they have those same grooves. It's just the process of removing the material which brings those grooves into visibility a bit more. The new process makes the brack track much more "raw" and indeed has some more "bite" and it is indeed noticeable even in the dry. Along with that it makes the same, for lack of a better description, jet engine noise when braking except louder I think. Still testing... and I haven't had the opportunity, of misfortune, of a real wet rainy day to take them out and really see how much better they are.
They are definitely the new rims however, with the AC3 on them, and the brake track is clearly distinguishable.

Oh, and as an update to that bit of concern I had, it was a non-issue. I was a bit concerned that there may be a "tick" with every revolution as the brake pads passed over that area, but I couldn't really feel a raised edge. The distributor I dealt with would have worked with me if I wanted to exchange them, but in the end I just kept them with the knowledge that I had at least made mention of it in case there was a problem once I glued them up and tried them. But there wasn't. The track is flat and there is no "ticking". They work perfectly. Again, it's just the process they apply to the brake track that makes some of those areas more visible than they would be otherwise, but so far the brake track does seem like it's going to be even better than it was.

Last Friday I went for a spin with a couple guys. I switched bikes with one guy for a while so he could try out my bike a bit for feel etc. He had Vision Carbon wheels with blue pads. We both noticed a big difference. To me, his brake tracks seemed like a skating rink for the brake pads and he concurred how good the Boras felt. I suspect he will have a set before too long.
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LionelB
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by LionelB

How is the new bora + 27mm veloflex clearance on the C60 fork ?

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Calnago
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by Calnago

Re the clearance with the Vlanderens/Boras in the C60 fork... nada... not enough, but these wheels weren't intended for that bike. The C60 really has a useable clearance for 25mm tires imo. The Vlanderens spin without touching the fork crown, but there's no real daylight to speak of between them. I wouldn't do it. As a comparison, it's like when I tried 25mm Arrenbergs on my pre-2015 Boras on my C59 or EPQ. I rode them, but there was a lot of chatter from small road debris bits being thrown between the fork crown and the tire. With the Vlanderens in the C60 fork... that experience would be even worse, with even less space to spare. There's more clearance in the rear than the front, enough that I'd be ok with. But on balance, 25's are the useable limit on the C60.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
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LionelB
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by LionelB

Weird to design a bike with significant different clearance front and back. Anyway, 25 are plenty for a C60 except on Roubaix day.

jonjones13
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by jonjones13

Just for clarification - there are three versions of Campag Bora brake-track
1 - gloss clearcoat
2 - in the last few years they released the Diamante brake track with the clearcoat milled off leaving raw carbon (better braking)
3 - the latest versions with AC3 which are apparently in shops from mid-July 2017

I believe you have 2) and the marks on your brake track are from (as you say) a park of the manufacturing process and are no big deal. Maybe they were the inspiration for 3) :-)

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Calnago
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by Calnago

To clarify above... there was never a "gloss clearcoat" on the brake track. The wheels come out of the mold looking as they do... no clear coat, even though it can appear that way.
The Diamante brake track has a bit more milling of the brake track once it's out of the mold, just to make it a little less smooth.
The current AC3 brake track, while I don't know the actual process used to create it, has more going on that just more milling. They claim to use higher heat resistance resins along with orienting the fibers in a manner which blah blah blah... never mind... because I'm not sure what exactly is different but the surface is very much a more textured surface than ever before, and does allow for more "bite" from the pads.
I have and am using the new AC3 Bora Ultra 50 at the moment.

@LionelB... the difference in clearance from the fork of the C60 and the rear brake bridge is pretty minimal... have seen much greater discrepancies than that for sure on other bikes.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
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robertbb
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Location: Melbourne, Australia

by robertbb

@Calnago: Very keen to know how much better the AC3 really is in the wet... subscribed!
It's ALL about the bike.

Greg66
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by Greg66

robertbb wrote:@Calnago: Very keen to know how much better the AC3 really is in the wet... subscribed!


Beat me to it by 90 mins! Exactly what I'd like to know too.

We're all very impatient to know this, so if you could get some friends to stand at the bottom of a steep hill with some hosepipes and buckets and drench you with water as you fly past into a braking zone, that would be ideal. :popcorn: :-D

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Calnago
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by Calnago

Ha... well I am curious too, but we (finally) have been having some decent weather for a bit, and I really want an awfully good downpour to really try them out in. Small drizzles will not do. Wet roads... pfft... do that all the time. No, I want to see the kind of weather that I would look out at and say... "na, no way I'm going out in this". But I will, at least long enough to test the brakes in it. It's probably going to be one of those "nice to have" kind of things, but if you don't it's not the end of the world.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

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