Bora first use - sand?

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

I just got a Bora set in, my first carbon. Reading in advance I saw a post claiming that Campagnolo clearly warns against sanding the rim. However in the manual it says to sand with 120 grit. I do not see any clearcoat, maybe some microscopic leftovers. Seems matte enough, either factory sanded or well sealed so a solvent wash could be enough. Sure I can sand it if needed but IME carbon glues well as long as it well washed (I have to work with and glue CF @ my day job. I hate sanding it but the rods I use come very glossy)

As for glue, I have the Conti carbon and will go for their procedure (I've seen most people prefer Vittoria but better heat resistance sold it for me, I am 200p)

Thanks!

by Weenie


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Calnago
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by Calnago

Where does Campagnolo clearly warn against sanding the rim? When they are brand new, give them a sand once round the rim then clean with acetone. I think I used 150 grit last time, or whatever is around. Doesn't take much. 10 seconds and you're done.
Re Conti carbon glue... I haven't used it but have never known anyone to prefer it over Vittoria Mastik One. I've heard it really stinks too. I've used the regular Conti glue but Vittoria is much better imo.
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

Alexandrumarian
Posts: 130
Joined: Mon Mar 28, 2016 6:34 pm
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by Alexandrumarian

Some guy on another forum said it...my manual is clear: 120 paper. To me this seems too aggressive so I used 240 but went over the rim several times, then washed it with alcohol.

I just painted the rims. Yes the solvents are nasty, luckily I have a mask for organic vapors. If you don't have one, better do it outside. It tacks super fast, so if you leave behind a thick trail, you can't really go back and correct it by more brushing. So it has to be spread well from the first strokes. Signing off to paint the tires.

Alexandrumarian
Posts: 130
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Location: Romania

by Alexandrumarian

Btw, first thing i did was to mount dry for stretching. It went on with so little effort (arenberg) that i started gluing right away. Perhaps from a safety pov the tightness of a conti makes sense?

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Calnago
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by Calnago

No, I have never had an issue with the Arrenbergs in that regard. The 27mm Vlanderens go on even easier, perhaps because of their bigger volume etc.... starting to get into mountain bike tire territory :). In fact, when mounting them I found that I had to ease off a bit or I would end up with too much tire at the end and a possible high spot on the side opposite the valve versus the valve side where that is more likely to occur.

But yeah, like you I've thought that before as well, that the conti's are so damn tight that it would be hard for them to come off even without glue. Not the case, but they sure are tight. I leave Contis on stretching rims for weeks if I can, but Veloflex you can pretty much mount straight away with no stretching.

Post back up here if you remember when you have to remove one of those tires. Tell us how the glue looks, whether it is hardened up a lot (like regular conti glue does), or whether it has retained a lot of its flexibility, like Vittoria Mastik does.
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

Alexandrumarian
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by Alexandrumarian

Please don't wish me a quick revisit to the work stand :D What will do instead is to glue rubber on some carbon leftover I have here and rip it apart after 1 week.

On the tightness, I am now thinking that while it can make a huge difference to our (handlebar battered) thumbs, on the road it might be a wash. Assuming the glue has lost its grip (age, heat, user error) then 70 to 100Kg skidding against the tarmac will easily rip the tube from the rim regardless of how tight it went on.

Speaking of grip, I just inspected the rims and decided to patch up a few areas that looked too thin. Then noticed a very thick area (from the first session 4-5h ago) so I scrubbed it with the nail. Peels rather easily and cleanly. Not reassuring but i also wouldn't want it to epoxy-like and make me use car levers and rip off the carbon when reinstalling. I guess that while rotating fast, lets say cornering forces are spread over a long stretch reducing the continuous stress on the glue. Seems like a dynamic system, with both glue and tire being soft rubber. The air pressure is surely essential in keeping the glue together as well. Must be a bit different than when gluing hard materials, where weakness in glue adhesion is guaranteed failure.

sungod
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by sungod

fwiw i use 0000 steel wool on new cf rims, just to help get rid of any release agent, then isopropyl alcohol to degrease

as above, i wouldn't stretch veloflex, they go on easy enough from new, and also interested to hear how the conti carbon glue works out

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dj97223
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by dj97223

Alexandrumarian wrote:Please don't wish me a quick revisit to the work stand :D What will do instead is to glue rubber on some carbon leftover I have here and rip it apart after 1 week.

On the tightness, I am now thinking that while it can make a huge difference to our (handlebar battered) thumbs, on the road it might be a wash. Assuming the glue has lost its grip (age, heat, user error) then 70 to 100Kg skidding against the tarmac will easily rip the tube from the rim regardless of how tight it went on.

Speaking of grip, I just inspected the rims and decided to patch up a few areas that looked too thin. Then noticed a very thick area (from the first session 4-5h ago) so I scrubbed it with the nail. Peels rather easily and cleanly. Not reassuring but i also wouldn't want it to epoxy-like and make me use car levers and rip off the carbon when reinstalling. I guess that while rotating fast, lets say cornering forces are spread over a long stretch reducing the continuous stress on the glue. Seems like a dynamic system, with both glue and tire being soft rubber. The air pressure is surely essential in keeping the glue together as well. Must be a bit different than when gluing hard materials, where weakness in glue adhesion is guaranteed failure.


One of the advantages of tubulars over clinchers is that the tubular is more likely to stay attached to the rim when you flat. If it were me, I would follow the instructions that came with the wheels and sand first, then wipe clean In fact, that is what I have done with 2 sets of new Bora's, and the Mastik and Veloflex adhered well; I didn't try to remove anything after 4-5h, but I certainly couldn't remove the glue now with just a fingernail.
“If you save your breath I feel a man like you can manage it. And if you don't manage it, you'll die. Only slowly, very slowly, old friend.”

Alexandrumarian
Posts: 130
Joined: Mon Mar 28, 2016 6:34 pm
Location: Romania

by Alexandrumarian

ok, finished them. Was a lot harder than i imagined - i guess i got cocky and thought no glue job can scare me (i build acoustic guitars, gluing is a second nature)

It went easily on the rim, but wherever it makes contact, it sticks hard. The seam was not even nearly centered to base tape or thread pattern but it tends to go down in the deep V of the rim. So then I tried to lift the crooked sections and rotate them as to get a reasonable centering of both thread and tape. My thumbs are blistered but the centering remained pretty much crap especially on the first tire. Pretty much the entire thread pattern leans several mm to one side. There is basetape showing on both sides so I guess it is safe enough. Spinning shows some vertical wobble but not horrendous. I guess i'm out of patience to try again now so will wait to cure and do a very moderate ride in 12h.

by Weenie


Alexandrumarian
Posts: 130
Joined: Mon Mar 28, 2016 6:34 pm
Location: Romania

by Alexandrumarian

First ride. I just couldn't wait anymore after looking at the bike the whole day. So only 10h instead of 24 of cure. Deflated a tire, tried to budge it. The glue is still flexible and I can see it starting to elongate under hard pressure but other than this, which is probably to be expected, they seem well stuck. But spinning in the fork, the front wheel is a real disaster. I have a bump at the valve (should have stretched harder in the first half, did it better on rear well so no bump) and the worst part is the skewed thread pattern. Just looks wrong. Once the honeymoon is over will take it off, as in Sept will go in the mountains.

They are surely fast, but do not slap you in the face with it, not that I had the guts to push it hard. Even so, if goes up to speed without feeling it. But the most obvious part is the cushy ride (I used same width and psi on clinchers before). It's a bit like moving from a rather rattly light small car to a large, expensive German car. I can still feel every jolt and bump, but well dampened. Didn't feel anything like this when switching from alu to carbon bars.

Previous wheels were still 25mm tires (Michelin power comp with latex), 110PSI (I'm around 210p) with home made DT Swiss 440 rims, 28/32 2x/3x Aerolites, Record rear hub, DT240 front hub.

Braking is fine (sound is priceless) but it has a delayed start. I guess it can be easily adjusted to and maybe there is a positive. I often start braking then thing I was cautious for nothing. In that second I lost some momentum or annoyed the group mate behind for nothing. The delayed response could let me back off with less "damage".

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