Hello
After a trip to the local Car Boot sale a few years ago we came home with a Cannondale F800 fitted with a Pbone D Head shock thingy.
Its sat in the back of the garage but my son loved the style of it and wants me to get it up and running, so after a quick lube and a few adjustments its like new well apart from the fork as it looks to be seized solid so how do I take it apart?
I have had a look around and cant find much info on the older forks?
Obviously I am a tight wad and it wont be going to Cannondale for a service
Now although its an older bike its high spec and my son is in two minds, should he keep the Cannondale or his 10 year old Saracen hard tail, Rock shocks STI gears, odd wheels?

I wouldn’t bother. You can get reducer cups or a reducer headset to run standard 1 1/8″ forks. Trying to get a seized old Headshock sorted could cost loads, and it’s just not worth it. To do it yourself, you’ll need certain proprietary tools, which might be available if you’re lucky, and will cost loads. And then you might need new parts, which even if available, will cost loads.

Can you tell I’m not a fan of Cannondale Headshocks?

You’ll need specific tools to take it apart. Not an easy job I’m afraid.

Thanks
He is happy to ride it as it is but the engineer in me would like to see it working again, I would imagine I have all the required special tools, could just do with some one who has done it to point me in the right direction

“I would imagine I have all the required special tools”

You could imagine that, and without wishing to be rude, I’d say you’re probably wrong. Headshocks require specific proprietary tools made just for that one job, so unless you’re a Cannondale service centre, I very much doubt you’d have the correct tools. That Cannondale, in their wisdom, made their forks non -user serviceable, is the main reason I hate them. Which is a shame as they are a great company making great products, mostly.

Trust me; you’re much better off ditching it and getting reducers/headset and some normal forks.

One issue that you might have though, is that Cannondale slightly changed the headtube internal diameter a while ago, from something like 1.56″ to 1.5″, I think. Maybe someone can correct me if I’m wrong. So newer reducer headsets might not fit. You can probably find some reducer cups on Ebay etc, which will allow you to fit a standard headset and fork though.

I have an F800 with a Headshock Fatty which seized on me. Sent to a Cannondale service centre (sorry can’t remember which one now) but it didn’t cost a fortune to fix. Great forks when they are working.

Clod hopper, you are not being rude I understand.
Going to give them a good soak and see if I can free them off them have a look at stripping them down.
It would be good if I can chat to some one who has done it, but as a few have said it may be better in the long run to fit a different fork, but I would like to have a go first

There are plenty of guides on YouTube. I pulled mine apart and serviced it after making a castle tool. That’s the only proprietary kit you need to remove the damper. Not all fattys are the same so it depends on the version you have.

This may also help you.

And this

DIY Castle tool

Good luck with it. Assuming you can remove the damper, there’s then the air chamber seals, which have probably gone. You can get new seal kits I think. Good luck trying to sort the damper out; that will need proprietary/specially made tools too. Then the needle bearing units and races will need looking at; good chance they’re all corroded and gubbed. I do support trying to get old things working again, but I think for the amount of time and money you’ll end up spending, it could just be better getting some reducers and an old Rock Shox or similar. Headshocks ran from 50 to 80mm I think, depending on year, but depending on the fork, you could get away with using up to 100mm.

They’re actually not that complicated and all parts are available*, they’re just fiddly and at first glance rather awkward due to needing more than a 5mm allen key and spanner to take a part.

You will need to source (or make) the proprietary castle tool to remove the damper but other than that there’s nothing unusual required.

They can be a bit of a fiddle to get back together but all the manuals are available online, and there are plenty of videos on youtube too.

basically if you really want to get it going again you can. it might be cheaper to look at an alternative but ‘becasue you can’ is often a better reason than saving a few £.

FWIW, by the time you spend £20 on some reducers, £30 on a headset and then £50 – £100 on a replacement fork you could just send it to someone like Tony @Thumbprint and have it serviced and rebuilt for less, so you might not even save any money.

Also worth noting that the p-bone is the older design, replaced by fatty but used on cheaper models for a while after. If it really is P-Bone D then likely to be from 1998/1999 (ish) and It’s likely to be 60mm travel. The D is fairly a low end model and won’t have much in the way of adjustment. It could also be coil and MCU spring OR air, it depends on the exact model/year and the decals may or may not actually match up with what is inside it! There’s also not much to go wrong with the basic ones either which is a good thing!

* replacement units/dampers etc can be expensive if sourced new, 2nd hand they pop up occasionally, but mostly they can be rebuilt with new o-rings for a few pennies, unless you’ve actually got some physical damage requiring a new unit then it isn;t likely to be expensive.
The bearings and races may be beyond saving if it’s been sat and has corroded over the years, on the plus side they are totally replaceable and are cheap though and not too hard to find. Most of the cost of sorting these forks out is in the labour.

Headshocks ran from 50 to 80mm I think, depending on year, but depending on the fork, you could get away with using up to 100mm.

80mm was the biggest travel Headshox, but due to the design they are actually long for their travel in terms of a-2-c length, and 80mm Fatty is within mm of a 100mm lefty, and all the F-series frames will run fine with 100 and 120mm forks.

is that Cannondale slightly changed the headtube internal diameter a while ago, from something like 1.56″ to 1.5″,

The Fatty/Lefty steerer size is 1.56 inch, but the headtube internal diameter is standard 1.5inch cup/49mm, but some of the older frames need a headset with a smallish insertion depth due to a lip on the inside. Measure to be sure, or use a pair of reducer inserts and a standard 1 1/8th headset.

I’ve still got 3 Fatty’s in regular use, oldest one from 1998 and still running sweetly, newest is 2006 and lives on my 24hr bike doing sterling service taking the edge off things 🙂

The P-Bone D was a coil/oil fork so no air seals and 60mm travel. the dampers can be a pain to remove, especially if the rest of the fork is stuck.

if there are spares still for it, you’ll be looking at quite a price to replace the bearings and bearing sliders if they’re pitted.

if you like the headshok idea, you’d be better off finding a working second hand set on ebay for about £50.

Have a similar situation (though my boy’s one is working at present) and I’ve decided I’ll swap in a reducer cup headset if it fails. The parts cost and faff aren’t worth it for the 60-80 mm of travel – but I have a couple of forks knocking about that make that more economic.

Current plan is to hope he outgrows it, and his two brothers don’t break it in their turn 🙂

though my boy’s one is working at present

Is that still my Wife’s old one on the diddy Blue ‘Dale?

Thanks for all your help.
He is quite happy to ride it as is with the seized fork, he loves the Retro Look of it!
I will let him ride it for now but keep an eye out for a replacement traditional fork to keep in case of a future issue.
Its labelled up Pbone D the frame is labelled F800 Cad2,
Heres the other bits
Sachs power Grip wavey shifters.
Centera rear mech
Deore LX front
Wheels
Mavic x221 Hubs well I haven’t a clue they look well made but have an oval with 4 weird symbols in it and 700 under it?
Brakes
Diacomp 7EXA levers with Shimano STX RC brakes
I cat find a full spec so no idea if its original or not?
Main thing is it looks good for an old bike and rides very well so he likes it

Just found the Cannondale catalogues on line but cant see the F800?
The funny symbol is Coda, looking at other specs it has different shifters and brake levers. He is out on it now so lets see if he still loves it when he returns!

Is that still my Wife’s old one on the diddy Blue ‘Dale?

Is indeed 🙂 – 1×9 and he loves it! XT v on the fron, Deore disk rear – odd setup but it works really well. Toying with a 1×11 / 1×10 update, but not until he complains a bit more. Headshock still works pretty well – bit stiff for him but does enough and looks cool apparently!

It has 2 more to deal with after him, itching for their go .. but I think no.2 will be out of luck as he’s overtaking him in growth…

After faffing around with mine, stripping it 10 plus times and it still leaked air!
It was about to become a solid fork. But then……

I took all the insides out and cut down an old suspension fork spring crammed it in the top, and refitted the top bits and now it’s non adjustable but springy!

FYI I made do with the tools I had around, it was a fiddle but after the 5th time I could do it in my sleep.

Its labelled up Pbone D the frame is labelled F800 Cad2,

the P-Bone D was a 1998 fork, only fitted that year as far as I know, but it moved to Fatty-D, Fatty SL and the Super fatty.

oh, found this: http://www.vintagecannondale.com/cannondale/headshok/headshok.html

“FWIW, by the time you spend £20 on some reducers, £30 on a headset and then £50 – £100 on a replacement fork you could just send it to someone like Tony @Thumbprint and have it serviced and rebuilt for less, so you might not even save any money.”

I do fully support the idea of fixing something rather than simply adding it to landfill, of course. And yes, of course it can probably be done. But in my own experience, this just isn’t worth it in terms of time, money and effort needed. From the sound of it, a full strip and rebuild with new parts, if it’s that seized, could well be more than £100-150. For that money, you could have something like a Rockshox Reba or SID from just a few years ago, in great condition (plenty on Ebay etc), which is far more user-serviceable and adjustable. The Headshok’s main strength is it’s stiffness, and when working well, how smooth it is. But they aren’t the easiest fork to maintain, and if they go wrong, it can be very costly to sort them out. And then there’s this:

“if you like the headshok idea, you’d be better off finding a working second hand set on ebay for about £50.”

Which makes spending 2 or 3 times that on getting a set which may well be badly damaged, fixed, seem like a mad idea.

“The Fatty/Lefty steerer size is 1.56 inch, but the headtube internal diameter is standard 1.5inch cup/49mm, but some of the older frames need a headset with a smallish insertion depth due to a lip on the inside. Measure to be sure, or use a pair of reducer inserts and a standard 1 1/8th headset.”

Thanks for clearing that up for me! So the frames are compatible with any 1.5″/reducer headset? Even better!

Clodhopper, your maths is sound, and I don’t disagree, it’s probably cheaper to look for a replacement. But as you have hinted at, sometimes ‘because you can’ is a good enough reason to fix something, and ‘time and effort’ are only wasted if you don’t get enjoyment and satisfaction from the task, if you do then it’s time invested not wasted.

If the OP was after advice purely on the £ costs involved then I’d recommend replacement every time, just like a I would for a pair of normal forks with ruined stanchions etc. But if there’s a will to keep using them or repair/preserve then it’s not just about £.

Thanks for clearing that up for me! So the frames are compatible with any most 1.5″/reducer headset? Even better!

yup 🙂 just be careful on the insertion depth as mentioned, some frames have the lip, others don’t. If they do then it may be necessary to either machine a bit off the headset cup or look at models with lower insertion depth. There are some specific models that are known to work, but most 49mm cups will fit or require only minor mods to fit. If you want to use normal 1 1/8th headsets then a pair of reducer inserts is ~£20.

Headshock still works pretty well – bit stiff for him but does enough and looks cool apparently!

Glad it’s still getting used! as long as you keep the boot in good shape and the bearings lubed that one will likely go on forever as it’s coil/MCU sprung with a friction damper, there is almost nothing that can go wrong in there on that model!

coil/MCU sprung with a friction damper, there is almost nothing that can go wrong in there on that model!

it’s not though, that’s the ‘M’ the ‘D’ has a hydraulic damper, and hydraulic lockout. That could go wrong, and the fork would be a pogo.

^ that was in reference to the one Brassneck’s lad has, which is an Fatty M (it used to belong to my wife), not the OP’s P-Bone.

ok, sorry, I should pay more attention. 😉

Morning, service is possible but not easy, you need a rubber mallet to get it out of bike. A park green pin spanner to open it up and castle tool to remove damper.

The big issue will be spares/cost, if it is seized you will prob need, needle bearing £20, new polymer £22, most of the fork seals are standard imperial O rings, you won’t get them in BBQ but they are out there. 5wt hydraulic oil to refill. You will need a new rubber boot as I could guarantee it is damaged and this is how the bearings got contaminated and seized in the first place, £12.

I have serviced loads of these, give me a shout and I can talk you through it. They are a good fork for cross country and really light for kids etc. but they are about 20 years old now.