UK trail bike. The story of an XCT5.
After messing around in the test area to get my post count up I can start a thread on my new(old) frame. The last time I visited mtbr was in October 2011!
I bought this in a private sale after seeing a listing on ebay. I think the seller is a user on here, and the deal included some raceface cranks and a seatpost, I suspect I will move them on just now. I built the bike up for now with donor parts from a couple of my other bikes, and will upgrade to more suitable parts in time. The forks i have fitted, Reba rlt's are a little short and this puts alot of weight on the front, this is the first and most important change i need to make.
In the meantime I have stripped the Curnutt shock as the rebound adjuster didnt seem to make any noticeable difference. upon stripping it I found that the return spring had moved and was no longer pushing on the needle so the settling was stuck on full slow.
I made a call to the UK importer of the bikes to order a seal kit but they won't sell me one, apparently I need special tools to strip and reassemble the shock. Which I do have. I will try the italian importer to see if they are more helpful......
Failing that, I will have to source all of the different seals separately, but this shouldn't be a problem. Just don't fancy having to buy ten of each size.
More as it happens. :)
Edited for clarity...
A little bit of a back story. I spanner for a few people, a couple of racers, one of which has now gone onto world cup dh events, and a few years ago both of these racers were on DHS mono's. The first Foes frame they had were '06 mono's, and they were fantastic, if heavy bits of kit. They pedalled like nothing else I have ever ridden, neither before or since. I always promised myself that whenever I saw a XCT4/5 on the trail that I would ask the owner for a short ride on it, as I was convinced that this was the bike for me.
When the later DHS frames arrived with the air shocks, although they were lighter they didn't seem to have that 'something' that the previous coil shock frames had.
These are rare machines in the UK and I had not seen one on the trails, and they very rarely show up on ebay or in the classifieds so when I saw this on ebay, I knew it was for me. This could very well be my dream bike.
Having spent the day that it arrived in the post looking adoringly across the workshop at it, as soon as I finished work the strip of the Cotic donor bike began. The strip and build took about two hours, and I rode the bike home, in the dark but was less than impressed.
The shock seemed to be lazy, and the rebound dial made no adjustment at all, being stuck on full slow. Not a good first impression, but a quick search on Google led me here to the thread that explains how easy the shocks are to service. I had never had one apart before, we used to use Guido in italy for service, and he was amazing. The shock was fairly easy to take apart, just a couple of special tools needed to fully strip the main body and remove the shaft from the bottom clevis. This evening the bare aluminium parts were polished and ball burnished and are ready to refit. 2.5wt oil is ordered and should be with me tomorrow.
nice! I like the polished bits. Your british'isms are a bit hard for us yanks to follow, though.;)
Originally Posted by kanerdog1x1
looking forward to seeing the bike built.
Hello Kanerdog, they do look nice polished, i had one for a coupla years, its an ideal uk do it all bike imo, please post a pic when its built up, next to your ktm!
Aha! Cheers guys.
It was your thread 'iheart' that convinced me to strip the shock, Thankyou.
And 'forgot', no KTM atm, it has been a couple of years since I had one. I made the move to road bikes a couple of years ago, but occasionally get the itch for an enduro bike so possibly in the future....
I have reassembled the shock for the most part, but could not complete it as the oil hasn't yet arrived. It was difficult to get the rebound needle to move freely, in the end I took a stronger spring from a ball point pen, and this helped. With no seal and no lube the needle moved freely, but as soon as the smallest amount of friction from the oring and lube were present, it would stick in the closed position. Roll eyes smiley.
You're going to love this bike once you get the shock sorted out. I have one, orange no less, but with a Ti coil on my Curnutt shock. Like you said this bike pedals like nothing else I have ridden and it's just a blast to ride. Good luck and keep us posted on you progress!
no ktm, ahh thats a shame, they would look v nice next to each other.
The bike is now reassembled, no drama bleeding the shock but the oil level was a complete guess. I have set it at 10mm which is probably on the high side. Can anyone tell me what it should be, I assume it is measured with the shock compressed onto the bottom out bumper?
Also, having searched the web for info on springs I am surprised to read that I have the correct spring for my weight, but it sags way too much, and becomes coil bound only halfway into the travel! Perhaps I need a ti spring?....
I measured the IFP depth on mine, with the shock empty. But I didnt get it perfect the first time ,and had to re-do it.
Originally Posted by kanerdog1x1
What is the stroke on your shock? Not sure if my measurements will work for yours or not.
here's my original thread. http://forums.mtbr.com/shocks-suspen...ck-723238.html
Originally Posted by iheartbicycles
I didnt have any directions from Foes, so I had to figure out the IFP depth myself - and I took two tries to do it.
The good news, is you shouldnt break anything if you're careful - so go for it. Here's all I did to find the starting IFP depth.
rebuild your piston
rebuild the shock body
Either depress or remove the schraeder valve internals - the way the IFP can move freely in the shock body - without air pressure causing any affect.
Insert the IFP into the shock body
Use the piston to push the IFP all the way into the shock body. screw the cap onto the shock body - and push the IFP all the way to the point where the shock is at bottom out.
If the bottom out bumper gets in the way, you will need to account for this later.
Now with the schraeder valve still depressed, or removed - reverse the process, leaving the IFP at the bottom out point. Take the shock apart, again - removing all internals, except the IFP.
Use a pencil or something else to measure the IFP depth.
If the bottom out bumper prevented your shock from fully bottoming out - measure the width and push the IFP down further - by this amount.
Now to make sure that during use your piston doesnt contact your IFP, you will want additional space between the IFP and the piston.
I recomend starting at 1/2". Go ahead and push the IFP in, further by this amount.
Re-install the schraeder valve core. you now want the ambient air pressure to hold the IFP at its current depth.
Go ahead and refill your shock with oil - making sure to get rid of all bubbles as you go. (cycle the piston, etc)
you should probably leave the coil spring off for now.
Once back together and before charging the IFP, cycle the shock to make sure everything is moving nicely and you dont have interference.
At these low pressures and forces, you shouldnt have to worry about any burps between air and oil chambers.
To be 100% certain you have good clearance - you might want to bolt the shock onto you bike, no spring and completely cycle the shock - all the way to bottom out. Do this carefully and slowely - as you still dont have any significant pressure holding the IFP in place.
When you're satisfied you have clearance - pressurize the IFP (minimum 50 PSI) and put everything back together.
You'll notice in my thread that I took two tries to the the IFP depth I liked. Once you get the hang of this, you have much more flexibilty in fine tuning your shock - you can really dial in how it ramps up, which is nice.
Disclaimer - I'm not a professional! I just have a bunch of Foes and decided to teach myself how to rebuild my shocks. This may or may not be the best way - but it works.
Thanks for the reply. I chose to fill and bleed the shock though the top rather than via the seal head. I should really have taken some pics, sorry. The shock is 2.5inch.
I have put a few gentle miles on the bike, to try out different air pressures. I can tell you that the difference between 65 and 100 psi is very noticeable. Also, when climbing in the middle ring there is very little pedal induced bob, certainly a lot less than when in the big ring. I am loathe to take the big ring off of the bike as it is so stable it demands to be ridden fast. But, the spring is intrusive on the ride, I think I am only getting about 80-100mm wheel travel.
I think I will try less air gap in the shock tomorrow to feel the difference, perhaps reduce it to 5mm.
Can't wait to get some more suitable forks. :)
Well well well. Someone on another forum suggested this might be the frame that was used as a test bike at bike radar, :- Foes 2:1 XCT 5 - BikeRadar
Upon close inspection of the images I am pretty certain it is. :)
I took a fone call yesterday from one of my racer buddies, he mentioned that he may have a couple of Curnutt spares on the shelf. Indeed, the stash included a longer steel spring, and it was a 450. Bingo! You can just about make out the felt pen markings:-
You can see here clearly the tool I made to hold the shock body firmly when unscrewing the top clevis or seal head:-
I have also set the air gap at 5mm with the shock compressed:-
Here you can see the difference in the lengths of the springs. I had to separate the preload spacer from the preload nut to allow it to fit. I love the way these shocks seem to be modular, the top spring perch is identical to the bottom one. :)
I have ridden the bike home this evening, and it feels so much better with the heavier spring. I could just get the sag correct with the first spring with four turns of preload, but it is correct with just two turns now, but feels so different. I suspect part of this is down to the reduced air gap, so next time i will try a larger gap, maybe 15mm, to feel what effect that has. My friend had a spin around his driveway to get feel for the bike, he reckoned that the rebound was too fast, I thought it was too slow! This confirms I have the correct weight oil in, the 2.5wt was a guess based on the condition of the oil taken out. I have it set now at one and a half turns out, and is a setting we both agree on.
Really need different forks though, the front end is holding me back now.
This image I took last week, before a bit of a ride.
You can see clearly that the forks are too short and the bike is sitting on its nose. It rode ok, but far from perfect.
Earlier this week I ordered a set of Rockshox Revelation forks for the bike, and set about fitting them. I knew I wanted the travel reducing to 130mm, but had no idea that the supplied 10mm spacers were not compatible. I have reduced many pairs of Reba's/Rev's in the past but these were all dual air models. The new RS forks are all solo air, and require a little bit of work to shorten the travel. To reduce the travel the air spring shaft needs to be shortened by the amount of travel reduction required.
I removed 20mm from the top end of the shaft, and redrilled the shaft for the roll pin. Once I was happy with the outcome, I decided to make a new shaft in titanium to save a tiny amount of weight but more importantly produce a very smooth and slippery shaft. The finish on the oe shaft is simply as the aluminium is drawn, and far from smooth.
Here you can see the difference, the ti item is smooth. :)
The other little mod I did was to the already fantastic new lockout lever.
It is supplied with a torx headed bolt which makes servicing a bit of a ball ache, so I swapped out the bolt with a stainless allen head bolt. Also turned the head down on the lathe so save hardly any weight.
And, as she stands this weekend:-
Had a proper ride this afternoon. It got dark, but that made it more fun.
I have fitted a reverb seatpost, and I am impressed. I have played with them before but never had a full ride on one. Its the ossum. Also took the cranks form my yeti, i wanted to try the 2x setup on the 26er. i think i will leave them on here to be honest, and get some 3x cranks for the yeti....
Also picked up some titanium hardware for the shock. Not fitted them yet, should get around to that tomorrow.
Bad idea using Ti bolts for the shock. The shear modulus of Ti is roughly half that of steel. It might be OK to install them on the links but you definitely shouldn't use them at the two contact points where the shock mounts to the bike. I used them on the shock mounting points on a Turner Burner frame only to have them snap.
Thanks for the heads up, but I don't think it will be a problem. The bolts have centres so I can check them periodically for runout and creep. If they are done up correctly, there should only be a very small amount of shear load on them, it 'should' be distributed through the frame via the shock bushes.
The foes has a low leverage ratio, much like my old my2000 heckler has. That survived fine with m5(!) titanium bolts on the front shock mount, and an m6 at the rear. If anything, I think the foes with the m6 at the front shock mount is perfect, and the m8 at the rear is over built.
No problem...could have been that the bolts I installed were shoddy, could've been a combination of my riding style and weight (@ 220lbs suited & booted) that caused the failure or all of the above. Regardless, for me the cost/benefit - risk/reward is not there for me to justify use of Ti bolts to mount my Curnutt shock.
In any case, I'm really enjoying this thread. Your XCT looks awesome, nice set-up. Looks like you have the Revelation on now, I didn't think I would but I really like the white fork on the orange. What travel are you running up front after your fork mod? What are your initial ride impressions?
:) the revs are set at 130mm now, i may possibly try 140 in the summer and when the trails get faster, but for now 130 is perfect.
Hose routing of these dropper posts has always been the part that put me off. I have installed a couple on friends bikes and they have always been a compromise of cable ties and heli tape. I wanted to make a proper job of mine.
Started with a Thomson seat clamp, as this is not only the most modern design, but it uses a barrel nut in the same way as a Salsa unit. I like this idea, but the Thomson also has the floating washer much the same as the seatposts feature, full of win.
Although the Thomson part is pretty low profile, certainly smaller than a Salsa, it still was very close to the reverb hose on the lowest setting. So i machined away a very small area, not so much for clearance as it still touches, but at least the hose won't rub the anodising off now.
The other part is fabricated from 6/4 titanium. It is actually the second try as the first item was a bit ugly. Fitted:-
There is still a patch of heli tape, and I will leave it on, but the hose doesnt touch the frame in any position. :)
I have managed to fit a couple of steady rides in this week, the light is holding on more and more as winter turns slowly to spring.
I am also starting to become an expert at removing and refitting the shock, and then rebuilding it. It has been out of the bike for one reason or another three times this week alone......
Lessons learned are that the IFP height should be about 10mm, this seems to make a noticeable difference to the rebound damping. With a smaller IFP volume/height, the shock had erratic damping, most noticeable in the rebound stroke with an audible 'clunk' that could be felt through the frame. Now I know that nothing could be touching inside, as it was in the rebound stroke so the piston&shaft would be travelling away from the IFP....
Lesson two is that careful bleeding is rewarded with much better quality damping. Goes without saying, huh? The best way I found was to fill, to the brim with oil while the shock was compressed. Refit the top cap, not tight, just so the seal is working. Then extend the shock and leave for a couple of mins. This should introduce a vacuum inside the body, and make any air bubbles hidden inside the damping circuit very big, and allow them to escape. Then, after a few mins, very slowly compress the shock. A slow compression is vitally important here as it keeps turbulence in the oil to a minimum. Then unscrew the top and you should be greeted with oil free of bubbles.
The damping is now very controlled, and the rebound adjuster makes very tangible differences to both the rebound stroke, and a little to the low speed compression.
I really like this shock. :)
I've been running 140mm up front from day one. Feels very balanced with the rear travel. The front stays planted on climbs, lively handling in tight singletrack, and comfortable bombing down. I started with a Magura Thor 140mm. Had some diving issues so I decieded to switch to a Fox Vanilla RLC 140mm. Coil front and rear are perfect together. Been toying with the idea of going 150mm and Ti spring with a Marzocchi 44 RC3.
Originally Posted by kanerdog1x1
The shock is super simple to work on.
Originally Posted by kanerdog1x1
Cheers guys. I love the way the shock is easy to work on too. :)
And, I like the quality of Fox forks, but I dont like the price/value ratio in the UK, they are VERY expensive. IMO they don't work as nicely as a RS fork that is 1/3 the price. And I particularly don't like the feel of vanilla forks, the springs feel too linear. A friend has picked up a Marzocchi 44ti within the last couple of weeks, and I am looking forward to trying these.
Stopped by the LBS today, which is normal for a Saturday, and came away with a bottom bracket to match the headset I bought from someone on a UK forum.
Fitted them both this afternoon, so I am one step closer to putting the Cotic back together. Thinking about getting gold hubs too....
Unbelievable thread and nice touches to everything. I'm in the process of rebuilding my curnutt and haven't quite found the sweet spot for IFP depth. I really like the repeatability of your measurement from the end of the shock body to the bottom of the IFP.
I see you've characterized a too small IFP depth (5mm) as having erratic rebound properties. What would you describe the effects of having too much IFP depth (15mm +)? I'm trying to get small bump compliance at speed more linear all though the stroke, i.e. not too much ramp up. I'd still like to tune the ramp up with the knob when a trail deems it necessary, jumps, drops, etc.
Any help would be greatly appreciated. Thanks and great bike!
I saw your comments in the other thread in the shock/suspension forum, thanks for the kind words here and also there.
Good questions. I would say that you could calculate the very maximum IFP volume/depth by determining the point at which it almost touches the damper rod/piston on full compression. Full compression would need to factor in the bumpstop being crushed to almost nothing. I would say you would need a clearance, say 2-3mm for safety.
The most I have tried is 15mm IFP depth, but this gave a very linear feeling to the shock, and it flew through the travel too easily. I personally didn't like this, but with your XTD shock you could play around with this setting on the trail.
Bleeding the shock 'my' way offers repeatability, and it is also alot less messy. I can have the shock out of the frame in 5 mins, washed, stripped, oiled, bled, assembled and washed again in a further 20 mins, and another 5 mins to refit it to the bike. So in a half hour or so I can experiment with a setting that does make a very noticeable difference.
Small bump compliance comes by having less air pressure to start with, but you lose some platform firmness. I happen to like the platform to feel firm, its the main reason I have the Foes. So for that reason I have settled on a very high pressure, I have it written down, pretty sure I am on 90psi ATM. Take notes of the settings you use, then add comments to them when you have ridden the particular settings, this way you have a record of what feeling the settings give.
Try it, you can feel a difference.
I read that you add oil from the top, exactly how do you do that? I just don't understand how to get oil "underneath" the IFP without introducing air? Thanks for the help.
I understand and agree with all of your points. Greatly appreciated
Ok, add the oil first, all the way to the top. This makes bleeding the shock easier. After bleeding, take the IFP, theres a hole in the top of it with a small screw. Take the screw out, pop the IFP back in the shock, set the height(this is the only really messy bit). Replace the bleed screw, and empty the remaining oil back into the oil bottle and reassemble the shock. Done.
Interesting. I was looking at that screw but figured it wouldn't work as the IFP would rotate when you try to snug it up. Teflon / No teflon, anything needed to make it seal?
There's a tiny oring, snugs it up just fine.
Didn't take long to think about the hubs, ordered them during the week, and took even less time to arrive.
The monkey in the shop also convinced me to get the matching jockey wheels too, even tho I really dont need them. They are nice tho....
Also in the pic above are a pair of Raceface turbines, which are my new favourite crankset. These are used, picked up from eBay. These have slightly bigger rings than the ones borrowed from my Yeti, 28-40, so should pair well with a 11-36 cassette when I go ten speed.
I also ordered a pair of Hope quick release skewers, I have adapted part of the front to marry up to the RS Maxle, so I now have a Hope Maxle hybrid.
This last week has seen some far from settled weather, but I have managed a few rides. Both weekends saw a visit to the Forest of Dean, and I only just remembered to take a pic at the top of the last DH section this afternoon.
No complaints from the bike as such, apart from the rear quick release may not have been done up tight enough as the wheel had moved quite a bit in the frame at the bottom of this downhill section. I thought the axle may have snapped which I have seen in the past with first generation pro2 hubs, but having taken it to bits just now all seems well.
The last of the components arrived this week for the new wheels, got around to building them today.
Not fitted to the bike yet, I am going ten speed at the same time and those parts have started to arrive too.
Now, the brakes on the bike at the moment are borrowed from my Cotic. They are Hope tech X2's and normally perform faultlessly. I have been a fan of Hope kit for years, and dont usually have a problem with braking power/performance. After a mid week night ride this week I noticed that the rear brake was pretty poor, so investigated.
The pads were shot which was a surprise as the pads were new only in November, and they had worn unevenly. Closer inspection revealed that the rear discmount/dropout has some over hanging weld that was interfering with the disc mount. I rode the bike, mud and all into the LBS this afternoon and used the disc facing tool to straighten things out.
Please forgive the dodgy iphone image, its all i had to hand. You can clearly see there was alot of material in the way. A new set of pads later and braking is back to normal. :)
Fed up of the orange, and I planned to red this up from the outset.
I like the red better, it has to be red, foes are red.
While the bike is in pieces, I am going to give everything a thorough clean, and service some bits. The rest of the bike is new, or nearly new. But it has had a hard couple of months, and the reverb was starting to lose air during the course of a ride.
On the right is one of the air seals, I found the torn away piece in the lower so it had been squeezed past the top out bumper. This was possibly a fault in assembly, as it would have been a tight squeeze.
On the left is a 10mm spacer I machined, to reduce the available travel to 115mm. Works perfectly.
And all clean, ready for reassembly. No more difficult to service than a pair of air forks, really glad I bought the tools and did it myself.
Cheers katana. You don't by any change have a soft spot for suzukis?
This isn't a proper update, as the bike is pretty much fully built. The LBS has ordered me a set of Hope brakes, just waiting for them to come in.
The frame was treated to a new set of bearings all round, seemed daft to put the old ones in even tho they felt ok. To help fit the main pivot bearings, i made a tool to draw them in, rather than belting them with le hammer.
I also picked up a decal kit from ebay, tho not technically the correct set as they are for a 4x, its close enough and crucially half the price of retail.... They look perfect fitted, tho I don't have a pic handy.
I sold the Renthal bars I was using, TBH hated the feel of them. Having ridden a few bikes with Burgtec bars, I was pretty happy to be donated a pair as the bend on them is really comfortable.
These were taken to be bead blasted to remove the anodising, and promptly powder coated white. :)
Proper update this weekend.
Mini-mini update, regarding a titanium spring. This:-
turned up on ebay a few weeks ago, attached to a broken 4x frame. I enquired with the seller about the spring rate, and he had it measured, the result was 450lb. Having made an offer for the shock only, we made a deal. It arrived this morning, and I popped over to my local suspension tuner, who I know very well, and used one of his tools to double check the rate.
The rate is exactly 450lb, which is surprising as a spring labelled '450' can usually measure anywhere between about 440-460. It is now fitted to the bike, and I am going to collect the brakes from the shop tomorrow.
I was also interested in buying the shock as it is XTD version, and I wanted to see if I could use the parts on this bike.
Upon stripping the shock, i was horrified to see the state of the oil. Not only was it black, but it was v smelly.
Although smelly oil isn't usually anything to worry about, black oil is. Something was worn inside and was depositing aluminium in the oil.Turns out the piston glide ring was completely worn, as was the piston oring, so the piston itself was rubbing on the shock body.
So much so that I assume the bearings were worn in the frame, and putting huge side loads on the shock. The shock bushes however feel brand new.
So, the shock stripped.
In no hurry to put it back together, I may get some parts made so that I can use this shock in the xtc, but I think it will be easiest to contact Foes to get the correct parts as spares, rather than make them. I would like to try a xtd shock, as the architecture is much more complicated inside, and I think the feel would be very different.
In the finish, the spring coming off is 444g, the ti spring going in is 230g. Happy, me.
I've heard many people converted the ITD shock to an XTD shock, because the XTD just worked/felt better...
I wonder if my XTD was doing this. It makes sense with how it felt on compression and rebound. I sent it back twice trying to get it fixed and the first time they said it was good, the 2nd time they said they rebuilt it, but it always felt terrible. Although I attributed it to the damping which isn't as speed sensitive as most any other shock (hit a sharp bump at high speed and it was like a jackhammer), this could have been contributing greatly if it was the case. The shock was new and did it from the start, yet a problem with the glide ring would greatly explain how it felt.
Originally Posted by kanerdog1x1
I would be very surprised if this type of wear would show in any less time than three or four seasons use without service, the hard anodised coating on the shock bodies is very robust. I have never seen this amount of wear before on a shock, but it is common on fork stanchions.
I would love to transfer the xtd parts onto my frame, but I am missing a few parts to make it work. No rush.
In other news, the bike is built, sans pedals. looks really nice, bright. :)
The bars refinished in white powder coat, to match the forks.
The ti spring fitted, and the dropper guide cleaned up and polished.
2x10 gear fitted now.
Brake rotors are 203mm front, and 183mm rear, i like the power and balance this combination affords. The chainstay protector is simply neoprene sheet, 3mm I think, with self adhesive backing. I have never tried it before in this application, time will tell if it is effective or not.
Very happy with the outcome, should get out on it on Monday and/or Tuesday.
Looks fantastic, I like the way the lowest spot on the top tube is actually out in the middle where it actually adds to the standover.
Looks really awesome man! I bet it's an absolute blast on the trails.
I've made a lot of changes to my XCT as well. Last change I want to make is from 3x9 to 1x9 drive train. Still breaking in the Curnutt Air. I'll throw up a post update with pics in a few weeks.
I had piston drag that eventually caused the separation of the piston head on my romic shock over a time period of about 2 weeks. Shock ended up literally coming apart. Before that, it had just been rebuilt a 2nd time to fix being blown. There's usually a glide ring that goes around a piston, or o-rings, or something, but if it's not machined right, something's crooked due to QC, or not assembled right, this would happen and I'd think the time span would just depend on how screwed up it is.
Originally Posted by kanerdog1x1
Long time, no update. I have been enjoying the summer, it's a scorcher!
Keep forgetting to take pics while I am out, mostly because one of my riding buddies has discovered Strava, so is trying so hard to beat me on certain sections. We hardly ever stop now, unless someone crashes!
Anyway, this evening I took a short ride out on my own, just before sunset as it is the only time of day worth riding in, as I find it impossible to get up early....
Happy with that, and taken with the iphone.
Wow, where is that. Reminds me of section of trail I used to ride in the Chilterns....
Originally Posted by kanerdog1x1