KCNC CB1 Lockage ... Any Tips?

Discuss light weight issues concerning road bikes & parts.
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worstshotever
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Joined: Sat Nov 28, 2009 10:07 pm

by worstshotever

So I feel stupid posting this, but I'm at the end of my patience and maybe I'm doing something stupid or else there's a cautionary tale in the making here.

I decide to remove my KCNC CB1 brakes today, and I can't get the front brakeset off the fork. I think the Ti bolts have seized, but weirdly the nut just spins in the fork but won't back out (or tighten). I see there is a small port on the front part of the housing with a tiny threaded cap, but I can't decide whether it is intended for lubing the area where the Ti bolt and nut come together inside the fork. Regardless, I've never done anything to service this area in the year and a half of all weather riding I've put them through. So, anyone else run into this problem with these brakes? Or more to the point, any ideas on how to unseize this thing so I can remove it? I lost the manual long ago, and the KCNC website isn't coming up for me at the moment. Thanks in advance. :beerchug:

artray
Posts: 1365
Joined: Fri Oct 07, 2011 2:08 pm

by artray

this happened to me with my trek but my rear breaks ,first the cb1 bolts are not ti ,there alloy ,i think you have corrosion due to contact between alloy and carbon ,,,it made my trek redundent no way to get the axle out ,,,i now only use ti bolts on my guru bike ,,,the reason its not loosening or tightening is due to a white acidic dust ,,if you do a search on google there are a number of suggestions to try and solve your problem but if not at least its not your frame as was in my case ,,,good luck hope it works out ok
artray

by Weenie


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Juanmoretime
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by Juanmoretime

I've never had this issue but then again it's why I use either grease or anti-seeze on every fastener.
RESIDENT GRUMPY OLD MAN.

jvanv8
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by jvanv8

I was just thinking this on my ride today as something I need to get done this week.

My KCNC CB1 front brakes that I purchased a few months after they came on the market also became seized to the effect the alloy bolt is stripped. They are using a very lightweight alloy for the bolt and I might have done more riding in rainy conditions than I anticipated. I believe I greased them prior to install and torqued them properly, but maybe I forgot the grease (seems unlikely though). I was merely swapping from one bike to the next. Or maybe my hex key was not in the best shape to cause the rounding of the bolt... which I rarely do, if ever. Currently, they are off-center, but still useable. There is a good amount of fore-aft play however which is not optimal at all. I think I will need to remove or replace the brake at some point this winter. I've only taken my bike into the shop 2 or 3 times in the last decade, but I do think they have better tools to deal with this type of issue.

Point is, you are not alone and I think my brakes were setup correctly originally. Maybe there is just so much an alloy bolt can take over the years of wet weather and epic seaside adventures. I will also seek an alternative bolt if I ever get the alloy removed.
Rear brake is fine.
The set has been used for 35,000 mi (~ 55,000 km).... so keep that in mind.
I have another pair on my 4 year old Addict R4 which are perfect (after... sic.. 400 miles?)
AX Vial Evo: 4970g
Addict SL : 5235g
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worstshotever
Posts: 573
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by worstshotever

Thanks, all.

Artray -- you're right, it's alloy, and it is definitely corroded. I've got the telltale white powder as well. So I guess the threaded nut is seized to the bolt.
Juan -- you're right, too. Usually it's my practice to grease fasteners before assembly, but it's entirely possible I forgot or was in a hurry or something when I installed these. I can't recall any longer.
Jvan8 -- glad to hear I'm in good company, although (sadly) mine have far fewer miles than yours!

The weird thing is, the allen wrench whole in the nut isn't stripped; the entire nut/bolt assembly just spins inside the fork. I say weird, because I would assume the long threaded bolt would be part of the brake's body, and thus unable to turn, if that makes sense. Anyway, I think I'll see how it likes a drill bit. The fork is toast anyway if I can't get it out, since the brake body is now too loose in the fork to be useable but still the bolt won't disengage. But maybe with some careful attention of the hand drill I can remediate the problem and get the brake off the bike. I'll destroy the brake if I succeed, but I was planning on replacing them with something else anyway so it's no great loss. I'll report back once surgery is complete.

jvanv8
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Location: Northeast USA

by jvanv8

My thought was, if worst comes to worst - worstshot, that I would use a hacksaw in the most endearing and tender way, to cut the brake bolt near the front of the fork. It might be possible with the right protection on the fork surface. Replacing the the front brake isn't the end of the world and I do feel I got my use out of it and then some. Either that or some sort of drill extraction which I'll leave to people more adept at that than myself. Attempting or witnessing the drilling out bolts, the preparation of meat sausages, and the preparation of a woman before a night out - are best treated with ambivalence, imho. The end result is always appreciated, however.
AX Vial Evo: 4970g
Addict SL : 5235g
My Cycling Blog
Strava: Wayward Cyclist

artray
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Joined: Fri Oct 07, 2011 2:08 pm

by artray

worstshotever wrote:Thanks, all.

Artray -- you're right, it's alloy, and it is definitely corroded. I've got the telltale white powder as well. So I guess the threaded nut is seized to the bolt.
Juan -- you're right, too. Usually it's my practice to grease fasteners before assembly, but it's entirely possible I forgot or was in a hurry or something when I installed these. I can't recall any longer.
Jvan8 -- glad to hear I'm in good company, although (sadly) mine have far fewer miles than yours!

The weird thing is, the allen wrench whole in the nut isn't stripped; the entire nut/bolt assembly just spins inside the fork. I say weird, because I would assume the long threaded bolt would be part of the brake's body, and thus unable to turn, if that makes sense. Anyway, I think I'll see how it likes a drill bit. The fork is toast anyway if I can't get it out, since the brake body is now too loose in the fork to be useable but still the bolt won't disengage. But maybe with some careful attention of the hand drill I can remediate the problem and get the brake off the bike. I'll destroy the brake if I succeed, but I was planning on replacing them with something else anyway so it's no great loss. I'll report back once surgery is complete.

If you can cut the axle bolt off and get the brakes out do it ,,,you can get titanium replacement axle bolts and nuts here http://www.pro-bolt.com/" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false; [if only i knew] also you need to check the rest of your bike for dust ,because it spreads ,cranks especially,if there is more dust your bike shop or a bike shop can clean out the inside of your frame , ,,,the reason you nut spins is because the dust is very accurate and has no effect apart from where it makes contact ,,,,artray

fitty4
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by fitty4

same thing happened to me, same brakes viewtopic.php?f=3&t=95009" onclick="window.open(this.href);return false; take the brakepads off and turn the the brake voila!

worstshotever
Posts: 573
Joined: Sat Nov 28, 2009 10:07 pm

by worstshotever

After-Action Report:

Nothing I could do to get this bolt to unlock. So I tried to drill it out. That was error. The aluminum nut that fit through the fork grinded away easily, but the bolt within was totally impregnable, and I couldn't drill away the entire nut housing without gutting the fork itself. This was all the result of my own stupidity and stubborn refusal to bring it to my shop, I confess. Ultimately, I just gave up and bought a new fork -- an Easton SLX 90. Silver lining: old fork weighed 410g, new fork, 280g, for a 130g savings.

jvanv8
Posts: 946
Joined: Sat Feb 02, 2008 2:37 pm
Location: Northeast USA

by jvanv8

Bummer. I think I was able to unfreeze the bolt by rotating the brake instead of trying to rotate the bolt. It's a good thing it worked because the bolt was stripped significantly by that point. Replaced with a fresh bolt with plenty of grease. Nice save though Worstshot.
AX Vial Evo: 4970g
Addict SL : 5235g
My Cycling Blog
Strava: Wayward Cyclist

by Weenie


lechat
Posts: 260
Joined: Thu Sep 30, 2010 3:32 pm
Location: S.E. TN

by lechat

the pivot bolt in CB1s is a stud not an actual bolt. check the set screw. removed, the stud should back out, at least you can see if it's turning.

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