Fox 40 RAD Prototype - Interview

Jul 29, 2012
by Fraser Britton  
Fraser Britton interviewed Fox Racing Shox's suspension gurus Justin Frey and Mark Fitzsimmons about the new 40 RAD fork, which has been absolutely dominating the World Cup DH series since its World Cup debut at Val Di Sole.



Fox 40 RAD Prototype - Justin Frey and his new Race Applications Development baby.

Justin Frey with the prototype Fox 40 RAD fork. Frey has been there for every step of its development process.



How long as the 40 RAD been in development?

bigquotesThe prototype FOX 40 RAD that our top athletes have been testing and racing since Val Di Sole has been a two-year development project in the making. RAD stands for "Racing Applications Development." The past couple of years we have been testing various chassis designs with our top athletes in an effort to fully understand each design's positive and negative characteristics. We have taken that testing data and designed the new chassis that is being raced on now. As for the damper and spring system; we started testing and racing that towards the end of last season in our current 40 chassis. We had our first official World Cup test session on the new chassis in Leogang, Austria where the World Championships will be this year the week prior to Val Di Sole. Due to travel logistics, we held a test in parallel with Aaron Gwin at the US Pro GRT race in Plattekill, which Aaron won the race on the new fork. Going into the Val Di Sole World Cup, we were happy with the test results and it showed as we swept the men's podium for the first time in the 40's history.


Fox 40 RAD Prototype - Compared to an old fork.

The original Fox 40 is nearly a pound heavier than the RAD prototype on the right - and yet Fox says that the new chassis is at least as rigid.


Fox 40 RAD Features

• Overall fork weight is reduced by almost a pound while keeping its stiffness.
• New spring system that adds more adjustability
• Retuned RC2 FIT damper developed to work with the new spring system.
• redesigned axle clamps
• Pressure release valves
• Updated lower friction seals



What are the major differences designed into the new 40?

bigquotesThe goal of the project was to give the riders a lighter fork with similar stiffness characteristics while reducing chassis feedback into the hands and arms. Which in the end reduces rider fatigue. The fork has a new spring system that offers more adjustability than the old one, it is lighter and changes where the weight is located in the fork. This helps with making quicker left-to-right transitions of the bike. The damper was retuned to match the new spring system.


Fox 40 RAD Prototype - Post Mount Brake.

Fox 40 RAD Prototype - post-mount caliper bosses.



Fox 40 RAD Prototype - Air bleeder valves.

Air-bleed valves on each side of the lowers.



Is the 40 RAD still in the R&D stages, or is it dialed in enough to be ready for production?

bigquotesWe continue to learn and make small changes to the fork based on rider, mechanic and field testing data. We will release more details later in the year as to the specifications of the production version. The plan is for it to be a 2014 model.


Fox 40 RAD Prototype - New Dropout system.

The new dropout system is much more compact.



How much influence have Fox-sponsored athletes had in the development of the 40 RAD?

bigquotesThere is no better place to develop high-end product than with the best athletes in the world. They are always looking for that extra edge of performance and their feedback is as honest as it gets. It they feel they are at a disadvantage, they let you know it. They also push the product to its limits and if it lasts a season to their abuse, the paying consumer reaps the benefits.


Fox 40 RAD Prototype - New arch and casting.

Each racer gets a custom name plate on the crown.



foxracingshox.com


129 Comments

  • 77 2
 Drop almost a pound?!?!?! That thing must weigh as much as a trail fork!
  • 46 1
 Im glad itll be in the low 6-lb range. Good job Fox.
  • 28 1
 So it would be comming in at almost an Boxxer WC weight but than stiffer & stronger,good job Fox that is what i call a fast step forward.
  • 21 1
 lowers remind me of super old marzo lowers. Don't know why.
  • 18 1
 By the time we can buy this, I'll be scared to see how much their next prototype will weigh Eek
  • 100 2
 by the time we can buy this. I'll be scared to see how much it will cost.
  • 13 0
 thing that scares me here....

lowers are slimmed down. if people were having puncture issues before, will slimmer walls not make that easier?

other than that it looks AMAZING, props to fox for pushing the envelope on this fork.
  • 12 0
 the question i have is.... can i just buy the lowers for my existing fox 40???? or will it all not be compatible
  • 4 0
 I saw a RAD 40 at the Northstar bike park 2 weeks ago. It looks sleek, and that unmistakeable arch. Guessing the dude who owned it was either a test rider or Fox employee. Matched perfectly on the V10c it was on tup
  • 2 0
 Bikeddict, You'll have to buy a new upper an lower crown for sure cause the prototype 40 isn't as wide as the one you have now.
  • 1 0
 Looks MEEEAAAANN
  • 2 1
 boylagz. the 40 and v10c you saw quite possibly could have been minnaar's bike
  • 1 0
 My question is, what on earth is all that air-bleeding stuff on the back side of the lowers all about?
  • 3 1
 While absorbing bumps fork is vacuuming some air through seals. Pressure is increasing and for become more firm, and less sensitive to small bumps/rocks etc. You will can push this little button below seals and release some air from the fork so it will can work normally Smile .
  • 3 0
 Uh... How can it be Minnaars bike? Other dude is borrowing his sled?
  • 2 0
 the crown looks like it just came out of a McDonnalds HappyMeal...a veeery happy one
  • 1 0
 Great that's awesome it will weigh a much as a boxxer world cup, I know what my new fork is going to be next summer.
  • 3 1
 goodbye boxxers. the only advantage of the boxxer was the weight loss, 40s have always been much more rigid and perform miles better. good job fox!
  • 5 1
 They should make a 36 RAD.
  • 2 0
 The arch reminds me of Magneto's helmet.
  • 1 0
 features of fox 40 RAD:

a very cool name.
  • 13 0
 Does anyone else think it looks like it has a mustache?

I don't know why, but this just makes me want it more...
  • 1 0
 yeah and it looks like the M from most older marzo forks from 08,09..
  • 16 5
 the best got better.
  • 9 0
 Save a pound in weight and loads of pounds in cash by going for a sh** before you ride
  • 3 0
 tactical dump
  • 9 1
 But fox being fox there sell it for about $1,0000,000. There shit is so expensive!
  • 2 3
 not if you compare it to the equivelent level from the other manufacturers.....

i bought a set of 36 180s and for the full rc2 fit version it was 120 cheaper than the top offerting from zocchi 66 rc3 ti..... and it is just better....fox's "entry level" arnt... what youve got to remember is that alot of rockshox and marzocchi forks have pathettic dampers that drive the costs down.... i cant say ive ever ridden a fox fork that didnt feel good... thats just the thing... to get a rs or zocchi fork of simalar performance you have to shell out every bit as much, if not more!!
  • 3 1
 rockshox dampers are just fine
  • 3 2
 Expensive yes, but you're paying for top quality. I love my Fox forks more than anything. Id love a 40 for the downhill bike when i could afford it
  • 4 0
 "The plan is for it to be a 2014 model." and as a result no one will buy any more new forks until then. No one wants to buy the current model (sweet though it is) and then find out that if they had waited a year they could have dropped a pound!
  • 2 0
 So you'll be able to buy them just after Sea Otter next year.
  • 1 0
 ok great if its a 2014 model i may have been able to save up enough pennies by then Razz
  • 5 2
 Yeeeee Fox! Still proving that even the best can be improved upon. I was a little worried after that CTD thing that they'd lost their touch, good to see I'm wrong!
  • 6 0
 Designed for BatmanSmile
  • 2 0
 So I'm not the only one who thought Batman when I saw it.
  • 1 0
 Quick! To the BatBikeShed!Wink
  • 2 1
 Good idea testing this piece at plattekill-the roughest mountain in the universe. Did fox splurge this time and use actual oil seals???? I doubt it. See you in 2018 when fox starts using oil seals.
  • 1 1
 Roughest mountain...LOL. You east coasters crack me up.
  • 1 0
 We ride all over the world from whistler to france and one thing still remains the same. Plattekill mountain has more obstacles per square foot than any other mountain east west south anywhere. Get rad wherever you ride but must check platt to get your full stripes.
  • 5 1
 When can we buy these?
  • 6 0
 It says that the plan is for it to be a 2014 model, so I guess late 2013 or start of 2014. I could be wrong, but I hope this helps and gives you a sort of goodish idea of when you can. Bet they will cost a lot:/
  • 13 0
 ^^Take a look at christiaan toys and you'll get the idea that money isn't a concern LOL
  • 1 1
 I'm guessing May/June of next year.
  • 1 0
 he'll have em in januari lol
  • 1 0
 woaaah fair enough, wish I had that much money! His v10 carbon looks so nice! I'm sure as soon as these come out he'll buy them not long after! haha
  • 2 0
 Thanks, I try, I try
  • 3 0
 what's the purpose of the air bleed valves on the lowers?
  • 2 0
 They release the air pressure that builds in the lowers when the fork and oil heat up. The expanding air dampens performance, so the valves bleed off any excess.
  • 2 0
 same as a nice moto fork
  • 2 0
 so is it an automatic system?
  • 2 0
 From the various stories I have heard, yes, it is automatic. But I've also heard a rumor that you can manually release the valves by pressing them in.
  • 3 0
 it would also be nice to push the fork down then bleed air so you can put in negative pressure, I do that all the time to my 888 and it makes it ride so much better
  • 1 0
 You have an air spring in your 888, no?
  • 1 0
 nope but if you unscrew the top cap on the damper side and push it down 40-70% into its travel you can get it nice and plush as long as you stay within those numbers anyway
  • 1 0
 just thought of something, can you buy one of those dorado/boxxer air springs and swap them in instead of a coil?
  • 1 0
 That's interesting. I dont think the air springs would fit.
  • 1 0
 A good idea, and I think that with a little machining knowledge it could be done. You would first need to make a new top cap, and maybe modify the down one too. Other than that, I don't see why it couldn't be done?
  • 1 0
 EOpen bath dampners on marzz forks and the Fox 40,s use air and a coil as a spring. The internal pressure also effects the dampning. Almost all forks with a good seal will build up air pressure and will benfit from burping out the air. By the way with marzz forks you can just take out one of the springs and add some air many of the Marzz forks came with an air valve for increasing the spring rate. I would not recomend taking out the coil in the Fox 40,s the dampners are dialed in to work with springs.
  • 1 0
 my 888 only has one spring... and i think if i got a top cap out from a 66 or something with an air cap to replace the spring id be pushing my luck with the seals not blowing out
  • 1 0
 I forgot about that.

That's a good thing on Marzocchis, you can swap cartridges between almost every fork with the same leg diameter, and pull out springs just like that (just not from the side with the neg. spring).
  • 2 0
 Marzocchis are user freindly easy to rebuild. Many parts are interchangeable..........oh shit this is supposed to be about the fox 40. Cant wait to see the new DVO forks. Sorry Fox...
  • 3 0
 I still stay with Kowa and BOS
  • 1 0
 Has there been any info about the fox upside down fork or whatever you want to call it? I remember seeing something about it last year.
  • 2 0
 If I remember correctly , they couldn't find any big advantages to their USD fork, so they didn't bother going further with it for the time being.
  • 1 0
 Ah right, I thought it could have been good considering the MX background
  • 5 6
 my 2011 40 is pretty rubbish, constantly losing front wheel grip despite trying all sorts of damping settings, if I set it slow it packs down and rides harsh, if i set it faster it bobs dangerously through compressions, bottomline is that it just doesnt absorb bumps that well and is a slow fork, you can feel it letting the bike down compared to the rear end which is V10 carbon with Fox rear damper, had better performance out of my old TF tuned boxxers from 07/08 so wont be investing in Fox forks for 2013/14, going for BOS or Bombers this time around.
  • 4 0
 uhh you my friend have a spring that is too stiff. lol
  • 2 0
 Proper suspension set up matters more than you can imagine. Find an expert (not just a guy at your bike shop, but a real expert), and get it set up for you. I have no idea who does it in UK, but for anyone in Vancouver, go see this guy when he gets healthy again (Concussed right now) suspension-therapy.com
  • 1 0
 You could try setting it up with more preload, or less low speed compression. Your preload will make it softer initially in the travel, aka better small bump compliance. Low speed compression holds you up in the travel during rolling whoops, corners, and g-outs. Less low speed damping will put you further down into the travel, allowing for more traction when suspension is compressed on corners/berms. However, with too little compression your fork will dive through berms and when braking.
  • 1 0
 less preload, ur only supposed to have three clicks of preload, if that doesnt work, new spring.
  • 1 0
 I was kind of happy when they said it wouldn't be out till 2014. Might give me time to try and save for one , don't I'd get the money though.
  • 3 11
flag baca262 (Jul 30, 2012 at 10:22) (Below Threshold)
 it you need to save up for it then you definitely don't need it. everything fox is way overpriced and way overhyped, in reality it's marginally better than the rs stuff and best looking out of the crowd, it's a freaking iphone.
  • 3 0
 ....K
  • 5 0
 " it you need to save up for it then you definitely don't need it"...

So that means no car... no house... no PC... no mountain bike...
  • 2 2
 car, pc and house is what you need for life in general and are well worth saving up 2 years for but a mtb fork that should be much better than it is considering it's price isn't. on the second thought, they might turn out to be MUCH better than the current 40's but i wouldn't hold my breath.
  • 1 0
 I saw these forks on Emilie Siegenthaler 2013 scott gambler when she was behind me in the queue to a bike lift in moraine, looked amazing!!
  • 1 0
 Will they make the 34mm edition, totally redisigned, full-blooded dirt fork that everybody wants? With similar style lowers?
Thats the question Smile
  • 1 0
 Can someone please tell me, what is the difference between 40 and 36 ? is it in the thickness of the tubes ? or the travel ??
  • 2 0
 both... 36s are 36mm in diameter 40s are 40mm..... 36s come in 160mm or 180mm of travel 40s are 203mm
  • 1 0
 thnx mate!
  • 3 2
 The 40's and Boxxer's are pretty much the same weight now. I wonder how rockshox's is going to make there boxxer lighter.
  • 3 0
 I want one.
  • 4 2
 Fox, still showing their the boss.
  • 1 0
 I don't want to wait till 2014! Haha looks so sick can't wait to get my hands on one!
  • 2 0
 Hopefully the service interval is greater.
  • 2 0
 finally a real brake mount
  • 1 0
 So can we expect this tech to be in the 36's at the same time, or will there be a delayed release for that?
  • 2 0
 ijust wish i could afford the fox 40 before the RAD model
  • 1 0
 I want one !!! mine are almost the oldest models ever!!
  • 1 0
 I like it. Those pressure release valves r like moto stuff. strong work.
  • 1 0
 i'll be impressed when they do an air version of the 40.
  • 1 2
 Fox are taking suspension forks to a new level! You have to bleed these! :O
  • 1 0
 no their not - this has been around since the 80's on moto forks
  • 1 0
 Fair point, never seen it before on MTB forks though.
  • 3 0
 Marzocchi Shivers have bleed screws in the top caps for the same purpose.
  • 3 0
 Monster Ts too.
  • 4 0
 this is exactly why mtb suspension manufacturers get away with ridiculous prices - people don't know shit about suspension.
  • 1 0
 ^ ^ ^ that could be said for just about every second part of our bikes.
  • 2 0
 The Lefty has had automatic air bleeding pretty much from the start 10 years go, I think - bleed holes with a filter to keep the crud out, to transfer the air both out of and in to the upper as the stanchion moves. Can certainly hear how much air gets displaced on mine, pssst pssst, haha! Big Grin
  • 1 0
 This fork is RAD!!!
  • 5 6
 I bet this fork will be 650b compatable.
  • 5 4
 Seriously? I highly doubt that. The application simply isn't there to start, among a zillion other reasons.
  • 1 1
 Gap between axle and arch...........
  • 2 3
 ^ Really now? Let me point something out to you...tell me which downhill frame will you be putting it on that is designed for 650b wheels? Have fun finding downhill tires and downhill 650b rims with through axle setups that can hold up as well.
  • 2 0
 It was just a thought.
  • 5 1
 Yeahhh I'm sorry dude, I don't know why I got so defensive over that...probably because it was 3am and I was tired as hell. Didn't mean to be so argumentative
  • 1 0
 Well, 2014 is still a year and a half away, so what happened to 29ers on XC can also come to DH or Enduro in the time being, regarding 650b, judging by the polls here on pinkbike. Personally, I cannot justify to myself ( ok, maybe I could if I really wanted it) that, buying a new standard is going to improve my riding.

Time will tell.
  • 2 0
 650b wheels fit in most 26 inch frames/forks with enough clearance, but its tight.
  • 1 0
 i dont think it would be designed around 650b but it might be ghetto possible..... it you can afford these you prob dint need ghetto fixes!!!
  • 1 2
 Is this with 20mm axle?
  • 5 1
 17.5 to shave weight
  • 2 3
 save the weight and reduce stiffens'n durability. I don't think it will be better to reduce 20 to 17,5 just for few grams.
Why not carbon axle 20mm to save some weight Smile Smile gg
  • 2 0
 It'll probably cost 300US and save 20 grams.....I wouldn't want carbon at that contact point anyhow......Don't get me wrong, I think carbon has it place, just not there.
  • 2 0
 I could see fox doing a 15mm axle for the 40.
  • 1 0
 I am SO not down for another axle standard... seems like that's the new way to incite gear lust, just make some new standard, oval wheels or something...
  • 2 0
 i'm curious as to why the axle assembly still uses pinch bolts...
  • 1 0
 Just thought about it for a sec and: I can't think of a way to make the clamps lighter than pinch bolts.
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