I only know this system from older times, perhaps current (2013) systems have different qualities.
It uses a wider head tube, because the shock is placed in the steering tube of the fork.
Usually, you can install adapters to the frame, so that you can use a normal suspension fork.
The main difference is that, instead of using telescopic stanchions, it has a squared tube with needle bearings.
When new, this system has virtually no static friction, so it will be VERY responsive to minor and/or high-frequency road irregularities, such as cobblestones, rough gravel, and rooty trail sections.
If something goes wrong it's usually the needle bearings themselves, which develop progressive "play", thus needing service/replacement, which in turn can become "complicated" since only Cannondale can service them or provide replacement parts, as far as I know.
I have seen some problematic Fatty forks in the past, but I have also seen A LOT of people happily using Fatty and Lefty (which uses the same principle) without issue.
Hope this helps!
bicycles.stackexchange.com/users/2355/heltonbiker
I have experience of them, yes.
They are great, when they work.
Other than the Lefty, they are probably one of the better short travel cross country mountain bike forks if by best, you mean stiffest & lightest.
But you are considering a 'BadBoy' which is usually used on-road.
In this case, a fork, headshok or not, is at best a bit of a waste of time, and at worst, a costly mistake.
The dirty secret of suspension forks, Headshok, or otherwise, is that they need regular and quite specialised maintenance, and if you don't treat them right, they suffer, and eventually die, and it's expensive to repair / replace them.
Are they any less reliable than 'normal' forks?
No.
Do they suffer from the same problems if left unmaintained?
Yes.
If you ride on road mostly, and want comfort, go for bigger tyres and a rigid fork for simplicity & reliability.
bicycles.stackexchange.com/users/None/
No, they are not reliable in the long term.
I have the same problems with a Ultra fatty dlr Headshok on my cannonade Caffein 2006.
Bought in 2008, it worked one year, then leaking oil, air and finally corroded , to function as a "stiff" fork...
I had it repaired at a german hedshok repair specialist, called"team88", they replaced the whole air suspension cartridge and overhauled the needle bearing .
costs ca 300 Euro plus delivery...
Then functioned pretty well for 2 years, now again leaking more and more air, and the last weeks it can't be fixed by filling air anymore because it is flat after some hours...
Im not sure if i want to repair it once more or just change to a stiff fork.
Has been really expensive already.
bicycles.stackexchange.com/users/30718/Fridtjof
I think the headset on the headshock system is propriatary and can't be used with existing 1 1/2in forks, but uses the same oversized headtube, so you can swap the headset with a standard 1 1/2in or use a reducer for 1 1/2in to 1 1/8in.
So, If you can't service the fork, You should be able to swap out the fork if you get a reducer headset (1 1/2in to 1 1/8in), a new stem, and a new 1 1/8in fork.
Headshock is pretty low travel, so you'll probably want a fork with low travel, an adjustable travel fork, or a suspension corrected rigid fork.
Sheldon has a page with some info on the system and links to manuals:
http://sheldonbrown.com/cannondale-headshok.html You could possibly rebuild it, parts are out there.
Honestly, unless you were getting a smoking hot deal, I'd avoid proprietary crap like this.
bicycles.stackexchange.com/users/2997/Benzo
Headshok is super-stiff, light and solid.
There is virtually zero stiction and the damping is butter-smooth.
I have a vintage, 2001 Bad Boy Ultra with Headshok and only recently re-built it (2013) – that's 13 years of reliable operation!
The guy who serviced it said I'll easily get another 15-18 years' use, as the updated bearings and seals are even better then original
OEM.
I love the true, solid lockout knob.
One quarter turn and the fork is shut off.
I only get 2.75" of travel, but it's plenty for an urban application.
bicycles.stackexchange.com/users/14409/Zachariah
I have Cannondale Quick CX 2010 with a headshok on a Fatty fork .
The lock never really worked, it locked but there was always a very small move causing noise when riding over a bump.
The bike mechanic suggested to avoid locking the shok.
It lasted about two years before I needed to start adding air every month or so.
One day it leaked oil everywhere, made nasty clunking metal-against-metal noises, the lock became non functional.
I took it to the shop, they fixed it somehow without replacing it, and it worked again for a few months before it started needing air added to it every week or every month, depending on still unknown variables.
It now failed again with the same symptoms, and it's completely collapsed: the shok doesn't have enough strength to support the bike's weight.
I have to take it to the shop again and it's not exactly cheap to get it fixed.
I had known about this, I wouldn't have bought this bike.
bicycles.stackexchange.com/users/3097/sebnukem
Does anyone have any experience of the Cannondale Headshok suspension system, where the shock is in the head tube / above the fork?  Are they reliable? I'm looking at a Cannondale Bad Boy 2 (2013) and am concerned that if something goes wrong it could be hard to rectify..
Experiences of the Cannondale Headshok system?
bicycles.stackexchange.com
<suspension><hybrid-bike><cannondale>
bicycles.stackexchange.com/questions/14775
bicycles.stackexchange.com/users/6334/jimmy_terra
It seems that cyclists either love or hate the Cannondale Headshok and other suspension systems. Many claim to have used them with relatively few issues while others feel the problems far outweigh any advantages. For people who ride on road mostly, and want comfort, bigger tyres and a rigid fork are recommended for simplicity & reliability.   This system is proprietary and often develops problems over time that require specialised maintenance, making it expensive and unreliable. There is less travel than on regular shocks, so while it is responsive and smooth, rigid forks with bigger tyres would improve comfort on roads without the complexity.
This system is proprietary and often develops problems over time that require specialised maintenance, making it expensive and unreliable. There is less travel than on regular shocks, so while it is responsive and smooth, rigid forks with bigger tyres would improve comfort on roads without the complexity.