Not by design. You can successfully run that in some cases, but that's not what the stem is there for and most can't be relied on to continually provide preload under vibrations and impacts. All aheadsets SHOULD be run with a topcap, and just because some people get away without it doesn't make it smart. I could probably run 4 disc rotor bolts instead of 6 and I could lace a 36 spoke wheel with only 28 spokes, and both would be rideable and save me weight, but it wouldn't be smart.
Crank Brothers headsets....who's got'em and how are they?
- Thread starter kidwoo
- Start date
On a somewhat related note, one ghetto fabulous way to "fix" your King headset is to cut the top ring under the stem. This is especially effective for Kings that have some miles on them...Apparently, that top ring gets mangled up after awhile on a DH bike with a dualie, so cutting it allows it to expand back to a position where everything remains tight once you crank down on the star nut...Basically, I had the same problem with my King on my V-10, and I tried this little trick and so far it's worked like a charm...And this way, I can feel blingy and superior to people running $30 headsets...
But yeah, if this thing gets loose again, it's FSA or Cane Creek time...I can just write the words "Chris King" on there with white out...
But yeah, if this thing gets loose again, it's FSA or Cane Creek time...I can just write the words "Chris King" on there with white out...
Ohhh i love abuse!!! lol im talking about when u spin the bearing in your hand.. But any way u old goat i think its smoother...
:biggrin:You may feel a difference in the seals, in which case "smoother" could actually be worse. You cannot feel the difference in bearings. Also, how do you feel it if there isn't a steerer, collet and crown race installed? Spinning the dust cap? sticking your finger in there and turning the inner race directly?Ohhh i love abuse!!! lol im talking about when u spin the bearing in your hand.. But any way u old goat i think its smoother...
It feels great sticking my finger in there!
I was always under the impression that the topcap and starnut were no longer structural members after the stem bolts were tightened. If the topcap assembly was designed to hold the stem down in use, surely it would be designed in a manner far superior to how it currently is. As davep suggested, the starnut will pull out of the steerer when actually subjected to the loads that you suggest it is supposed to deal with. I'm open to discussion on the matter, but when running the easton (havoc) stem in the no-topcap guise I had no dramas, which leads me to conclude that the thomson did have an inferior clamping mechanism (especially given that the two stems were the same weight)... and that given appropriate components, you can run your headset without a topcap just fine.
I was after some advice for my particular setup (direct mount), and am going to try degreasing everything + using a light coat of loctite bearing retainer on clamping surfaces for now and see how that goes. If all else fails, I'm just going to break out with the headlock once a week or so to keep things tight.
Udi, you're 100% correct. The top cap and star-nut are for one main purpose only........ To adjust the load on the bearings. Once A standard stem is tight or the upper clamp on the fork (direct mount stem) it's not necessary. Still, a standard stem is the best way to keep the fork from becoming loose.
Again, it CAN work without the topcap if the stem has sufficient clamping force and the system is never severely impacted or vibrated, but that's not the way the system was designed or engineered and it's not a failure by Thomson to have engineered it for the intended setup.
The topcap isn't designed to handle the full force of the system in use, it's designed to return the system in the case of minor displacement caused by heavy vibrations. You can think of every component in the system as a very small spring, and under dynamic use that axial force is really helpful in maintain stem position on the steerer. Like I said, you can run 28 spokes on a 36 spoke wheel and it will probably work, but it's not how the system was engineered.
My point is, is it worth it to save a couple of grams and have to worry about this, especially knowing it's against the intent of the folks that designed your bike? In extreme cases you could actually crush a properly designed steerer. This is unlikely on a DH fork, but considering a steerer isn't supposed to be specc'd for those kinds of clamping forces it's technically possible and the reason you could never get away with a capless setup on a high-end road bike.
The topcap isn't designed to handle the full force of the system in use, it's designed to return the system in the case of minor displacement caused by heavy vibrations. You can think of every component in the system as a very small spring, and under dynamic use that axial force is really helpful in maintain stem position on the steerer. Like I said, you can run 28 spokes on a 36 spoke wheel and it will probably work, but it's not how the system was engineered.
My point is, is it worth it to save a couple of grams and have to worry about this, especially knowing it's against the intent of the folks that designed your bike? In extreme cases you could actually crush a properly designed steerer. This is unlikely on a DH fork, but considering a steerer isn't supposed to be specc'd for those kinds of clamping forces it's technically possible and the reason you could never get away with a capless setup on a high-end road bike.
The new thread asking about the Crank Bros headsets reminded me of something...
I like the cane creek design, I think it's clever and efficient. I also think it is exactly the same as any old-school loose-ball headset from the 80s or earlier. We used to get so excited about "cartridge" bearings, looking down our noses at Shimano hubs for example. The big innovation here is NOT combining the outer race and bearing cup (pick up ANY non-cartridge headet to see the same thing), it's fitting an inner race permanently to a "loose-ball" setup and combining it with the aheadset collet to ensure proper preload and bearing alignment.
I like the cane creek design, I think it's clever and efficient. I also think it is exactly the same as any old-school loose-ball headset from the 80s or earlier. We used to get so excited about "cartridge" bearings, looking down our noses at Shimano hubs for example. The big innovation here is NOT combining the outer race and bearing cup (pick up ANY non-cartridge headet to see the same thing), it's fitting an inner race permanently to a "loose-ball" setup and combining it with the aheadset collet to ensure proper preload and bearing alignment.
I have used Chris King's on my fs xc bike and on my 07 sxt with a 66 and Diablous stem on it and never had a problem with them loosening. I have tried the Sunline V-one hs very tight design like mentioned but the crown race is big and alum so you have to be careful setting on the fork crown it bends very easy. Also they have dis continued their headsets. The V-one can be bought for the price of a FSA pig dh but I have had a Pig DH last 4 hard use years never loosened only reason I go rid of it because I sold the bike to a friend. As for the Crank Brothers I bought a Sage SL which is the deep cup stainless well it chipped when the lbs tried pressing it in. It's on its way back toCB for replacement. I can say the deep cup freeride is a pain to get set and should a stainless steel hs really chip or crack? I can say they are extreemly light and very small they have probably the lowest stack height but I am kind of doubting it being able to hold up to any abuse. They are really tiny
Does anyone know of a really low stack height hs besides the Crank Brothers?
Does anyone know of a really low stack height hs besides the Crank Brothers?
My shop was blowing out all Crank Brothers headsets because they had so many complaints.
The lowest stack height headset that I found other than CB was CC S-8 at 27.4mm. CC 110 had the lowest lower height w/ 12.05mm (28.6mm total). I ended up getting the FSA Pig Pro (31.4mm) because I didn't want to deal with headset problems.
With a steel cup like the crank brothers directset the tolerance are more important then with a alu cup. Because the youngs modulus of steel is roughly 3 times higher then aluminium you also get a 3 times higher force on the steel cups then with alu cups.
According to the Aheadset standard you need a ID of the headtube between 33.90 and 33.95mm. But when I look at the size of a park tool reamer it is 33.80mm So that would already give you a very tight fit.
I just ordered a CB directset, I will measure everything before it goes in. When it seems like it will be a tight fit I will just send the headset back or see if I can get the headtube reamed to correct tolerances.
According to the Aheadset standard you need a ID of the headtube between 33.90 and 33.95mm. But when I look at the size of a park tool reamer it is 33.80mm So that would already give you a very tight fit.
I just ordered a CB directset, I will measure everything before it goes in. When it seems like it will be a tight fit I will just send the headset back or see if I can get the headtube reamed to correct tolerances.
which one did you order? What kind of bike is it going on? The CB sl sage which is their freeride/downhill hs is very tricky and very fragile. I am affraid to do drops or dj with it and I don't even think it will hold up to the constant pounding of rock gardens. Not only is the ss very brittle but the cup walls are very thin. Only thing I could see these good for are a road bike or fixie or xc race bike due their extreme lightness.
What other complaints were they having? Unfortunately there is nothing close to their 20.56mm stack height.
Just ordered a cane creek 110 for my new V10 build, I've heard good things about them, Ill let you guys know how it works out once I get a few rides on it. As for the Thomson stem I sort of have to agree with Udi, it does not seem to clamp as hard as some of the other designs I've seen, but you have to admit the machine work and quality is bloody beautiful, I wish they would come out with a direct mount option, until then however I have a sunline direct mount on order.
I recently returned from a two week trip to Chile with two of our team riders.
We had the CB OPIUM DH steel version installed on their Orange 224 rigs and after two weeks of full on DH runs and two major races the Valparaiso Urban DH and the Chile National DH race, the headset has come through with out any issues. They do seem to require a little extra care to install but if done properley they are pretty tough. Our whole team will using them on the World Cup circuit this year.
Transcend Magazine DH team.
We had the CB OPIUM DH steel version installed on their Orange 224 rigs and after two weeks of full on DH runs and two major races the Valparaiso Urban DH and the Chile National DH race, the headset has come through with out any issues. They do seem to require a little extra care to install but if done properley they are pretty tough. Our whole team will using them on the World Cup circuit this year.
Transcend Magazine DH team.
CB products lasted 2 weeks? That must be some kind of record.
It is unfortunate that CB came out with a great design with very low stack height but with very poor reliability/install problems. The headset cracked while installing if you weren't careful. And some of them broke while riding. The shop (will be nameless) gave up and blew out the inventory. Not worth having your customers mad or deal with warranty issues.
I like CB in general. Great designs, great customer service. But it is a hit and miss with their products, especially in terms of reliability, even with the same product. Since the headset is a new product for CB, no one should be surprised that many people are having problems. Especially compared to FSA, CC and CK who have been making headsets for years.
couple of things is anyone have real luck with the CB headsets? Are people finding the bearing steel hs or the stainless holding up better. I assume by the design of the bearings they are none replaceable with the cup being the outer casing for the bearings and they are not cartridge bearings
I am running a Crank Brothers Opium SL on my Norco Six due to a short steerer tube. I love it, and I got it for about $70 on Ebay. I'm running a Lyrik and weigh about 220, and I ride pretty hard too. No complaints yet. I heard about issues installing it though, so I took it to Downhill Zone in Seattle to have them install it for me.